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Form Function and Evolution of Vertebrates:

Form Function and Evolution of Vertebrates Bio 224 Elizabeth A Spudich & Michael O’Connor

Bio 224:

Bio 224 Course : BIO 224: Form, Function and Evolution of Vertebrates Term: Winter 2010_2011 Credits: 4.0 Lecture : Monday 9-11;Wed 9-10 TEC 209 Recitation 601 : Wed 10-11 TEC 209 Instructor: Dr. Elizabeth Spudich Office Hours: MW 8-9am Office/Phone: Tec 311 Teaching Assistants: Kevin Smith (lab) Texts: Vertebrate Life: Pough, et al 8 th ed 2009 Any assigned supplementary materials

Bio 224:

Bio 224 Course Description Bio 224: This course is an introduction to the principles of organismal biology. Using the Subphylum Vertebrata the course will explore the major classes: fish, amphibians, reptiles, birds and mammals using select model species. The course will compare how these groups evolved anatomically and physiologically. The course will investigate how the interactions between molecular genetics and the environment determine evolutionary pathways. As an integrated course we will pull from diverse fields and employ a variety of techniques including traditional textbook instruction, readings from current literature, bioinformatics, group interactions and cutting-edge research from Drexel faculty.

Bio 224:

Bio 224 Academic Expectations: Students are responsible for any material covered in lecture, the corresponding material in the textbook and any handouts received as supplementary material provided by the Instructor or TA. I expect all students to be punctual for lecture and Recitation. I expect you to keep current with your readings I expect you to act maturely, responsibly, and collegially in this class. I expect you to keep aware of all project due dates, exam and quiz times and any course announcements placed on the BbVista Web Page In return, You can expect me to be punctual and prepared for all lectures. You can expect me to be organized, fair, and accessible to you. I will also try to tell you ahead of time about any changes in the syllabus/schedule.

Bio 224:

Bio 224 Computers will be allowed for note-taking purposes or in-class group work, only. If the professor/TA feels the privilege is being misused/abused Computers will be banned from lecture/Recitation. Computers on quiz days are not to be powered up/opened until all quizzes are handed in. Cell phones as a means of communicating emergency situations In the event of a university wide emergency, Drexel University will be sending out messages to the cell phones of students, staff and faculty. Therefore, since I do not like being interrupted by the ringing of cell phones, I will ask you to keep your cell phones on in vibrate mode. This does not mean that you should access/ answer any phone calls during class. Should the entire class receive a message from the university at the same time, then, certainly, you may access that message.

Bio 224:

Bio 224 Academic Honesty The following is the official Department Statement on Honesty: "Academic honesty is extremely important. Cheating, academic misconduct, plagiarism, and fabrication are serious breaches of academic integrity and will be dealt with according to University policy set up by the Office of Judicial Affairs". There is a ZERO tolerance policy towards cheating. Cheating is an extremely serious breach of academic integrity and will be dealt with severely according to the guidelines set out in the Drexel Student’s Handbook . Students who cheat or participate in cheating will be reported to the University’s Office of Judicial Affairs for disciplinary action. NO EXCEPTIONS Cheating will result in an automatic zero for the assignment and immediate referral to the appropriate Department Heads for further disciplinary action, including failure of the course and possible dismissal from the university.

Bio 224:

Bio 224 Assessments Bio 224: Midterm exams 30% (15% each) Recitation Quizzes 15% Recitation Participation and Homework 10% (completion of due dates and readings for project) Final Exam 25% Project (portfolios on comparative evolution) 20%

Bio 224:

Bio 224 Recitations: theses times will be used for a variety of purposes; administration of quizzes, Review and clarification of Lecture material and time to work on group cladistics project, review of supplementary material. ATTENDANCE at recitations is mandatory. Two percentage points will be subtracted from the recitation contribution of your grade for each absence. Quizzes: These will be administered during the scheduled recitation periods. Material covered on the quiz will be from the listed week’s lecture material. Make-up quizzes will not be given unless a University approved excuse is provided. Any other extenuating circumstances must be discussed with the instructor. Examinations: These will be administered during a Wednesday Lecture time as scheduled. They will cover all material from lecture, textbook and any supplementary material for the block of material in question. 75% of the exam will be multiple choice, True/False and matching type questions. 25% of each exam will be short answer/essay/application type questions.

Bio 224:

Bio 224 Make-Up exams: No make-up exams will be given unless a University approved excuse is provided. Any other extenuating or emergency circumstances must be discussed with the instructor. See Below. Scheduling of make-up exams will be at the professor’s discretion. Only ONE time will be scheduled. If the student does not take the make-up at that time the student will receive a ZERO on that exam. Other Circumstances: Any preplanned functions (NCAA sporting events you are competing in, weddings, family vacations, planned medical procedures, religious obligations, etc) conflicting with the quiz/exam schedule must be brought to the Professor’s attention with-in the first week of class. The student and professor will then schedule the affected quiz/exam to be taken PRIOR to the function. Final exam will be held during the Official Exam Week. Final Exam will be cumulative with an emphasis on material not previously reviewed in an Exam.

Bio 224:

Bio 224 Policy on Incompletes : Incompletes are granted to students if they have been unable to complete all the assignments listed for any course. They are granted only under extreme circumstances. If the student feels their circumstances warrant the issuance of an incomplete they must discuss this with the course instructor. At this time both parties will agree upon a time frame for the completion of the course material which will be NO LATER than week two of the next Quarter. If work is not completed within the agreed upon time frame then the students will get a ZERO on all assignments not finished and their grade will be calculated accordingly. Guaranteed Grading Scale A+ = 98-100 B+ = 88-89.9 C+ = 78-79.9 D+ = 68-69.9 A = 92-97.9 B = 82-87.9 C = 72-77.9 D = 62-67.9 A- = 90-91.9 B- = 80-81.9 C- = 70-71.9 D- = 60-61.0 F = <60



Slide 12:

WEEK LECTURE TOPICS Recitations wed Chapter 1 Jan 3 Classifications Environmental considerations Intro to course/project 1 2 Jan 10 Basic structures Early vertebrates Review lectures Cladistics overview 2, 3 3 Jan 17 MLK Holiday No Monday Lecture Locomotion Review Lectures 4 Jan 24 Locomotion cont. Respiratory Quiz week 1-3 Lecture/project reviews Hand in first part of project (Wednesday) 5 Jan 31 Cardiovascular Midterm thru locomotion Review for midterm 6 Feb 7 Reproduction Review Lectures Collect data for part two of project 7 Feb 14 Thermoregulation Quiz weeks 4-6 Discuss where each group is with the project Review lectures 8 Feb 21 Osmoregulation Midterm Respir. thru Thermoregulation Review for exam Hand in part two of project (Wednesday) 9 Feb 28 GI changes Review for midterm Begin part three of project 10 March 7 Biomechanics Quiz weeks 8-9 Discuss the Super Tree 11 March 14 Finish up and review for final No recitation EXAM WEEK Final is cumulative (60%new; 40%old) Upload completed portfolios

Bio 224 Course Organization:

Bio 224 Course Organization Part 1: Introduction to vertebrates Part 2: Comparative form and function Part 3: Molecular genetics and environmental specializations Classification Major structural relationships Broad environmental considerations; Water, Air, Land Evolution Early extant and Extinct forms Skeletal Muscular Respiration Cardiovascular Reproduction Thermoregulation Energy budgets Osmoregulation GI changes Biomechanics

Group Project Bio 224:

Group Project Bio 224 Part One: In each recitation section Students will be grouped Given a set of species aligned with Taxonomical group Each Student group will decide which characteristics to evaluate One must be at the gene level Evolutionary relationships will be built based on their observations

Group Project Bio 224:

Group Project Bio 224 Part two: Exchange of information Students will exchange information of their species with a similarly aligned group in a separate recitation section They will repeat their analysis on the new set Compare and contrast the relationships: How do the characteristics tracked affect the organization? How does your organization change as new species are “discovered”

Group Project Bio 224:

Group Project Bio 224 Part Three: Super-Tree?? Each recitation section will attempt to build a “Super-Tree” Readings and Discussions on placement of groups Whose characteristics are more informative?

Things That Bother Dr Spudich:

Things That Bother Dr Spudich Lateness Constant Cell Phone checking MP3 players Surfing the Web, reading the newspaper or a novel while I am lecturing Asking the person next to you a question about my lecture when I am RIGHT HERE! Asking “will this be on the Exam?” Asking “is there a Curve?” E-mailing me after the final to see what you can do to make your grade better

Any Questions?:

Any Questions?


Vertebrates More than 57,000 Extant species of vertebrates Live in almost all of earths habitats Diverse body forms Diverse behaviors Feeding Reproduction

Major Groupings:

Major Groupings Broad groupings based on differences in embryonic development Presence or absence of embryonically derived membranes With membranes = amniotes Without membranes = non-amniotes;mode=fit&amp;maxwidth=510


Vertebrates Amniotes Sauropsids Reptiles Birds Synapsids Mammals Primarily terrestrial Non-Amniotes Myxinoidea Hagfish Chondrichthyes Sharks Osteichthyes Bony fish Urodels / Anura / Gymnophiona Amphibians Primarily Aquatic

Non Amniotes:

Non Amniotes Embryos are enclosed Membranes come from the mother Component of the unfertilized egg Not usually a ‘true’ membrane Vitelline membrane Species specificity Polyspermy Protection

Myxinoidea and Petromyzontoidea:

Myxinoidea and Petromyzontoidea Hagfish = Myxinoidea Live on seabed 70 species Lamprey = Petromyzontoidea Migratory Live in oceans, spawn in rivers 38 species

Myxinoidea and Petromyzontoidea:

Myxinoidea and Petromyzontoidea Elongate body form Limbless Scaleless No internal bone Agnathans (cyclostomes) Jawless

Myxinoidea and Petromyzontoidea:

Myxinoidea and Petromyzontoidea Hagfish are missing some characteristics shared by more derived chordates No real vertebrae Yet shares some characteristics Has a cranium


Chondrichthyes Cartilaginous skeletons Extant species Neoselachii Sharks and rays Sharks 403 species 15 cm – 10 meter Rays 534 species Dorsoventrally flattened Bottom dwellers


Chondrichthyes Ratfish = Holocephalii 33 species Single membrane covering the gill structures Long tails Buck teeth Live on seafloor and eat crustaceans and mollusks


Osteichthyes Boney fish Too diverse to completely characterize Two broad groups Lobe finned = sarcopterygians Ray finned = actinopterygians


Sarcopterygians Lobe finned Only 8 species still survive Most closely related to terrestrial vertebrates Boney structure of limbs

Actinopterygians :

Actinopterygians Ray finned fishes Highly diverse Over 27,000 species named Thousands more expected to be discovered 150-200 new per year Chondrostei Birchirs , sturgeon, paddlefish Neopterygii Teleostei (most abundant)


Amphibians Combined Urodela , Anura and Gymnophiona groups “Double Life” Aquatic larval form Terrestrial adult All have bare skin Respiration and osmoregulation


Amniotes Three fetal membranes Formed from the cells of the fertilized egg Amnion encloses the developing fetus Chorion facilitates nutrient exchange Allantois facilitates gas and waste exchange


Amniotes Tend to be more terrestrial Some secondary aquatic species Sea turtles Whales


Amniotes Well established by the late Devonian Period 416 million years All with similar characteristics Had scales,not haie or feathers Very dilute urine Simple lungs Single heart ventricle


Amniotes Land masses moved and environments changed Amniotes evolved specialized physiologies Oxygen extraction Temperature control Osmoregulation Circulation

Sauropsid Amniotes:

Sauropsid Amniotes


Testudinia Turtles, tortoises and terrapins Land and sea dwellers Hard shell Nothing similar in all the other vertebrates


Lepidosauria Lizards, Snakes, Tuatara All have scales and similar skull morphologies Tuatara are found only in New Zealand 2 species 5000 lizards 3015 snakes


Crocodilia Alligators and crocodiles 23 species in all Varied sizes Up to 7 meters Skin has tiny bones under the scales Osteoderms Very attentive parents


Aves Birds More than 9670 species Evolved the ability to fly in the mesozoic Evolutionary record shows feathers evolved before flight First for courtship Then specialized for flight

Synapsid Amniotes:

Synapsid Amniotes


Mammalia Traced origin to the Paleozoic era 4800 extant species All feed young with maternal milk Placentals – Eutherians Placenta extensive and gestation is long


Mammalia Only in Australian Marsupials – Metatherians Kangaroos, koalas Have placentas but short gestation Immature young External pouch Monotremes – Prototherians Platypus and Echidna (spiny anteater) Young are hatched from eggs

Basic Structures and Evolutionary Relationships:

Basic Structures and Evolutionary Relationships


Relationships Animal Kingdom Phylum Chordata


Relationships Phylum Chordata Urochordata Cephalochordata Vertebrata


Symmetry Generally bilateral on external viewing Left and right sides mirror images


Asymmetry Many Internal organs/ structures have an asymmetry Via same molecular mechanism Paracrine signaling via Nodal Transcription factor Pitx


Asymmetry Via same molecular mechanism Cells on the left side secrete Nodal protein Autocrine signaling causes Pitx2 expression Transcription factor


Chordates Defining characteristics Notochord Solid midline bar of tissue Dorsal hollow nerve tube Pharyngeal gill slits Endostyle Glandular tissue important in feeding Post-anal Tail

Embryological Linkages:

Embryological Linkages Vertebrates have relationships with other animals because of common embryologic patterns/structures/ timings


Deuterostome Common cleavage patterns after fertilization Complex cellular reorganizations Gastrulation Formation three germ layers Ectoderm, Mesoderm, Endoderm triploblasts


Deuterostome Internal body cavity called a coelom Forms from a splitting of the mesodermal layer Gut tube open at both ends mouth and anus


Deuterostome Classification as Deuterostome reflects the timing of mouth formation Relative to gastrulation 2 nd opening forms the mouth First opening become the anus

Non-vertebrate Chordates:

Non-vertebrate Chordates


Urochordates Tunicates/ Sea squirts Marine Filter feeders Sessile as adults (most) Free swimmers as larva Chordate structures most recognizable in larval stages


Urochordates Used to think these species were ancestral to other chordates Now feel the sessile adult is a more derived form


Cephalochordates Small and fishlike Amphioxus (lancelet) Active larval stages Burrowing sedentary adults


Cephalochordates Myomeres Segmented muscle blocks along body wall Sequential contraction drives forward motion Notochord extends all the way to the head Support for burrowing actions


Cephalochordates Have Pharyngeal slits but no gills Small enough to use diffusion from body surface for gas exchange Slits used for feeding


Cephalochordates External coelom called the atrium Ventrally positioned Opened to the environment at the atriopore Flow of water out during filter feeding Likely an ancestral structure


Cephalochordates More derived characteristics similar to Verts . circulatory system Dorsal aorta Ventral pumping structure Pharyngeal vessels Specialized excretory cells called podocytes (we have in our kidneys)

Who’s more ancestral?:

Who’s more ancestral? Visible determinations Cephalochordates resemble vertebrates more closely than urochordate Urochordates more similar on the molecular level

General Vertebrate Structures:

General Vertebrate Structures


Vertebrae Small, sequentially arranged units Hard bone Hard cartilage Enclose the spinal cord ( a.k.a dorsal nerve tube) Forms around the notochord Assumes it role as rigid bar

Prominent Head:

Prominent Head Cranium Hard structure anterior to the vertebral column Protection for brain Houses many complex sensory organs Some call refer to the subphyla as Craniata

General Vertebrate Structures:

General Vertebrate Structures


Vertebrae Small, sequentially arranged units Hard bone Hard cartilage Enclose the spinal cord (a.k.a. dorsal nerve tube) Forms around the notochord Assumes it role as rigid bar

Prominent Head:

Prominent Head Cranium Hard structure anterior to the vertebral column Protection for brain Houses many complex sensory organs Some call refer to the subphyla as Craniata

Molecular Control of A-P patterning:

Molecular Control of A-P patterning Diversification of A-P axis patterning Formation and diversification of “head” structures Preceded by some alteration at the gene level

Patterning along A-P axis:

Patterning along A-P axis Other organisms have complex segmentation patterns Defined head regions Exact positioning of appendages Aligned on specific body regions

Hox genes:

Hox genes Drosophila uses the Homeobox gene cluster Related transcription factors Expressed in the early embryo Defines the placement and morphology of a region

Hox genes:

Hox genes Eight genes in Drosophila cluster Arranged along the chromosome in the order of their anatomical expression 5’ gene is expressed more anteriorly

Hox genes:

Hox genes Most animals have some pattern to them possess homologues Radial patterning need 1-2 Early bilateral species have more

Genetic Duplication :

Genetic Duplication Gene duplication of this cluster was needed to get complex patterning in vertebrates Amphioxus (cephalochordate) has one cluster Jawless vertebrates (Lamprey) have two clusters

Genetic Duplication :

Genetic Duplication A second duplication event occurred in jawed vertebrates 4 clusters

Independent Molecular Evolution:

Independent Molecular Evolution Once duplicated each cluster/gene will evolve separately Duplications within the cluster expands the number of usable genes More derived animals have 13 per cluster Loss of genes will modify which aspects of patterning each Cluster contributes to

Evolution at Cellular Levels:

Evolution at Cellular Levels Derivation of cranial and jaw structures parallels the appearance of Neural Crest cells “Fourth germ layer” Contributions to the vertebrate body plan AS significant as those of the other 3 germ layers

Evolution at cellular levels:

Evolution at cellular levels Migrate away from their initial location and move to numerous parts of the embryo

Contributions of NCCs:

Contributions of NCCs Form the flat bones of the cranium Nerve ganglion of sensory organs in the head and body Seed the pharyngeal arches to drive jaw formation Formation of the 4 chambered heart Innervation of the GI tract to force directional movement of Food/waste Pigmentation patterns

Evolution of NCCs:

Evolution of NCCs In amphioxus cells with similar positioning and gene expression Not migratory In some tunicates ( urochordates ) recent discoveries show a similar population Migratory Pigmentation

Body Plans:

Body Plans Primitive vertebrates larger than non-vert. chordates 1 v 10 cm Need more than simple diffusion for most processes Need increased food supply

Body Plans:

Body Plans Also more active Organ systems that work faster Increased predation More awareness of the environment Protective integumentary system First to change was likely respiration Increased efficiency in O 2 extraction permissive for all the rest

Compare and Contrast:

Compare and Contrast

Brain and Head Comparisons :

Brain and Head Comparisons Non-vert . Notochord extends to tip No cranium No special sensory organs Simple brain and eye Vert. Head extends beyond notochord Has a cranium Tripartite brain Complex sensory organs

Pharyngeal Comparisons :

Pharyngeal Comparisons Non-vert. Pharyngeal slits for feeding Many slits each side Non-muscular pharynx Movement via ciliary action Arches are collagen Vert. Gill arches support slits for respiration Fewer slits per side Muscular movement Arches are cartilage

Feeding Comparisons :

Feeding Comparisons Non-vert. Food moved via cilia, not muscle Intracellular digestion No liver/pancreas; midgut cecum Vert. Food moved by muscle contraction Extracellular digestion Discrete liver and pancreatic tissue

Circulation Comparisons :

Circulation Comparisons Non-vert. Ventral pumping w/acc. regions No neural regulation Open system Blood not for gas movement; no RBCs Vert. 3 chambered ventral heart Closed system Neural control of heart Blood for gas transport; RBCs

Excretion and Osmoregulation Comparisons :

Excretion and Osmoregulation Comparisons Non-vert. No special kidney Coelom filtered by solenocytes via negative pressure Filtrate moved to atrium and expelled Body fluids same composition as sea water Vert. Glomerular kidneys Ultra-filtration of blood Filtrate moves into archinephric ducts Fluid more dilute than seawater; kidney used for volume and divalent cation regulation

Locomotion Comparisons :

Locomotion Comparisons Non-vert. Notochord main support for muscle Myomeres are V-patterned No lateral fins just tail fins Vert. Notochord main support for body muscles Vertebral elements around notochord W-shaped myomeres Dermal fin rays on tail Dorsal fins

Embryologic Patterns:

Embryologic Patterns Invertebrate cellular differentiation is predetermined Autonomous specification Vertebrate differentiation due to induction Conditional specification

Patterns of Cellular Commitments:

Patterns of Cellular Commitments Autonomous specification Mosaic development Most invertebrates Invariant cleavage patterns Cell fate predetermined Factors localized in the oovum Morphogenetic determinants

Conditional Specification:

Conditional Specification Commitment driven by interactions between adjacent cells Induction Regulative Development If cells are removed/rearranged early enough fate can be changed

Germ Layers :

Germ Layers First identified by Christian Pander All animals (except sponges) have 2 or 3 Communication between the layers drove induction Ernst von Baer documented the evolutionary links between the layers Germ layers gave rise to the same structure in all species


Diploblasts Ectoderm- Outermost germ layer Superficial layers of the skin Nervous system and most of sense organs Endoderm – innermost layer Majority of the digestive tract lining Lining of digestive glands Respiratory surfaces Taste bud, thyroid, thymus

Mesoderm :

Mesoderm Mesoderm - middle layer Last to appear in animal development and evolution Becomes the notochord Most Muscles Most Bone Circulatory and urogenital systems

Mesodermal Contributions:

Mesodermal Contributions Mesoderm has a medial-to-lateral regionalization Dead center region is notochord Paraxial region segments into somites Bilateral Bones and muscles of trunk Muscles of limb

Mesodermal Contributions:

Mesodermal Contributions Intermediate regions Kidneys and collecting systems Gonads and accessory genital organs Lateral plate mesoderm splits Dorsal aspects contribute to limb bones Ventral aspects contribute to viscera

Mesodermal Contributions:

Mesodermal Contributions Internal coelom forms in the mesoderm Creates cavities to house large internal organs Pleuroperitoneal and pericardial Forms the lining of cavities Pleura/ pericardium/ peritoneum Abdominal mesentery

Mesodermal Contributions:

Mesodermal Contributions Head region has no lateral plate Cranial somites contribute muscles of head and neck Facial expression Branchiomeric (pharyngeal) NCCs contribute to the connective tissue structures in head Bones of cranium and jaw Cartilage of gill arches


CNS Neurulation similar in all vertebrates Ectoderm folds on itself to make a tube NCCs emerge when fold complete Universally, the control lies with the notochord Head regions give rise to three divisions Forebrain, midbrain, hindbrain

Specializations in Tissue Types:

Specializations in Tissue Types All animals have collagen as major ECM molecule Verts . organize it to form tissues used in structural elements Bone Joints Appendages


Keratin Unique to vertebrates Ectodermal derivative Highly organized External protection Outer skin of tetrapods Appendages like, scales, horns, beaks, hair



Integumentary System:

Integumentary System Boundary against outside environment 15+% of total body weight Osmotic and volume regulation Protection Exchange Sensation Metabolism Energy storage

Mineralized Tissue:

Mineralized Tissue Hydroxyapatite is harder than calcite (clam shell) Able to with stand acidic conditions Evolution linked to muscle anaerobic metabolism Many types of vertebrate tissues can be mineralized

Mineralized Tissues :

Mineralized Tissues Enameloid Mesodermal enamel-like tissue in dermal scales Enamel and Dentine Ectodermal derivatives in teeth Most mineralized tissue in verts. Cementum Holds teeth in socket

Mineralized Tissue:

Mineralized Tissue Mineralized cartilage of the Chondrichthyes Bone most mineralized of the internal skeletal tissues Mesodermal Two types of bone in Verts. Endochondral formed from cartilaginous templates Dermal bone from connective tissue membranes in skin

Dermal Bone:

Dermal Bone Primitive form of mineralized tissue Found in osctacoderms Armored fish Exoskeleton Early verts. had the external armor and a sparse internal cartilaginous endoskeleton

Cranial Skeleton:

Cranial Skeleton Skull has three components Chondrochranium Splanchnocranium Viscerochranium Dermatocranium Neural crest needed for ossification Chondo . and Splanchno . Dermatocranium in only a few extant species

Axial Skeleton:

Axial Skeleton Segmented vertebrae Cartilage or bone Forms around notochord and dorsal neural tube Notochord is lost in most tetrapods

Striated Muscle:

Striated Muscle Also a segmented pattern Folding patterns will span several body segments Increasing complexity Myomeres in jawed verts divided into Epaxial (dorsal) and Hypaxial (ventral) regions

Feeding/Digestions :

Feeding/Digestions Increased size means increased energy needs Digestion, respiration and circulation are linked Mechanical digestion Most verts. are particulate feeders “bite” size portions


Feeding/Digestion Chemical digestion Pancreas, liver Salivary glands Early verts. no real stomach, large intestines Single emptying chamber - cloaca


Feeding/Digestion Evolved as feeding needs and food sources changed Specialized Stomach Salivary glands Large intestines


Feeding/Digestion Control of feeding also developed Filter feeders eat all the time Accumulation of energy stores Pancreatic hormones to regulate energy storage


Respiration Cutaneous respiration seen in primitive verts Still important in amphibians Larger sizes means efficiency needed Gills and lungs increase surface area Gill lammellae

Circulatory System:

Circulatory System Fluid for stabilization of internal environment Transport of gasses, wastes, hormones Blood Liquid plasma Cellular componets Gas transport (RBC) Immune surveillance (WBC) Clotting control ( Thrombocytes )

Circulatory :

Circulatory Closed loop Arteries carry blood away Veins return Between are systems of smaller vessels Arterioles Capillaries Venules

Circulatory :

Circulatory Control of flow through tissues Arteriovenous anastomoses Shunts through capillary beds Change flow to tissue based on metabolic requirements

Circulatory :

Circulatory Changes at the cellular level Arteries with stand higher forces Thicker walls Muscular regions to control flow and pressure Venous compliance Need to stretch Blood volume stores


Circulation Tubular heart Three chambers Sinus venosus receives blood from venous systems One way movement to the atrium Valves prevent backflow Ventricle has largest muscles and moves blood to the gills


Circulation Vessels in gills called aortic arches Gas exchange Carotid arteries to head Dorsal aorta to body Cardinal veins return blood to the heart Anterior and posterior Portal systems Renal and hepatic Filtration before re-enters circulation


Excretion Kidneys from the intermediate mesoderm Segmented in form Handle nitrogenous wastes Regulate minerals Originally just divalent cations Ca, Mg, Mn , Phosphate


Excretion All have three regions Pronephros Mesonephros Metanephros Only the opisthonephric regions functional in adult vertebrates


Nephron Similar filtration units in all verts High pressure forces fluid from blood Controlled by the podocytes Filtrate is conditioned by resorption and secretions and emptied into the cloaca

Non-Vertebrate Chordates:

Non-Vertebrate Chordates True Nephric / glomerular kidneys a vertebrate feature Protonephridium in non-verts Filters coelomic cavity Solenocytes similar to the podocytes


Reproduction Paired gonadal tissue Usually in the body cavity along dorsal wall Ovaries have follicular cells Testes have seminiferous tubules Early verts had no ductal system of transport Release into the coelom Transported via archinephric ducts

Nervous System:

Nervous System Basic functional unit is the neuron See myelination in the jawed verts Organized ganglion and fibers Hierarchal arrangement Central – brain and Spinal cord Peripheral – fibers serving distal structures

Nervous system:

Nervous system Conscious v. Unconscious Somatic nervous system Special Sensory input Motor output Striated muscle Autonomic Nervous System Visceral sensor input Visceral output Smooth muscle

Special Senses:

Special Senses Taste, smell, touch, sight, smell hearing Ectodermal derivatives Specialized to ecology Air/water properties Chemosensory mechanisms Electromagnetic radiation Pressure/Gravity


Brain Expansion of the Dorsal Neural Tube in the anterior regions Three basic vesicles Forebrain – smell Midbrain – sight Hindbrain – balance/homeostasis Secondary derivations Telencephalon – integration Diencephalon – relay station/hormonal control Cerebellum – motion coordination only in jawed extant verts

Early Vertebrates:

Early Vertebrates Chapter 3


Conodonts Microfossils seen through the Paleozoic era Comb-like structures made of Apatite Similar to dentine in structure Fossil record show animals with these arrays share vertebrate features Early attempts at mineralization

Extinct Vertebrates:

Extinct Vertebrates Earliest soft bodied vertebrates at 540mil years ago Myllokumingia China 3 cm in length Distinct craniums W-shaped myomeres

Extinct Vertebrates:

Extinct Vertebrates Ostracoderm fossils at 500-480 mil. years ago Dermal armor fragments World-wide distributions by the Ordovician period Complete articulated fossils in Bolivia, Australia, North America


Ostracoderms Small 12-35 cm Jaw-less Torpedo shaped Armored Polygonal plates Head shield Scales Sensory canals and extra protection in the eye region


Ostracoderms Mineralized tissue in the armor of ostracoderms is enamel ( oid ) and dentine Basic unit is the odontode Toothlike projections forming in the skin Dentine core, enamel( oid ) covering and a base of acellular bone


Ostracoderms Evolution of large bony head shields driven by several forces Protection Insulation of the anterior electroreceptors Mineral storage

Ostracocderm Radiations:

Ostracocderm Radiations Most had small armored scales Some had larger shells Carapace Some fossils suggest the presence of a cerebellum Not seen in extant agnathans No true jaws but movable plates Circular, caudally positioned mouth Midline dorsal fins Some had pectoral girdles and fins

Extant Jawless :

Extant Jawless Less derived than the Ostracoderm and Conodonts Lack jaws and two sets of paired fins

Hagfish (Myxinoidea):

Hagfish ( Myxinoidea ) Mostly marine Deep sea cold water Slime glands in body wall Mucus and protein Contact with seawater turns it into a slimy shield Defense mechanism Body knot and sneezing clears mucus

Hagfish (Myxinoidea):

Hagfish ( Myxinoidea ) No vertebrae Internal anatomy has a lot of primitive forms Rudimentary covered eyes Oral tentacles Accessory aneural hearts in liver and tail Concentrated body fluid

Hagfish (Myxinoidea):

Hagfish ( Myxinoidea ) More derived structures too Keratinized tooth plates Pincer like motion to tear flesh Retractable tongue True heart is neural and 3 chambered Red blood cells Neural crest cells

Lamprey (Petromyzontoidea):

Lamprey ( Petromyzontoidea ) Similar in size and shape to hagfish Radical differences Vertebral structures Arcualia Very small and homologous to neural arches


Lamprey Parasitic Oral hood Hypertrophied upper lip Tongue analogous to vertebrate tongue Horney spines to rasp a shallow wound No enlarged stomach Liquid diet Large eyes


Lamprey Dilute body fluids Well developed kidneys Nitrogenous waste Osmoregulation Neural heart Vagal nerve control Gills employ both flow through and tidal ventilation Tidal less efficient When attached

Generalized Gnathostome Features:

Generalized Gnathostome Features Originated from an agnathan radiation Upper and lower jaws Teeth evolution dissociated from jaws Allowed for new feeding patterns Firmer grasps Teeth to cut and grind Herbivory possible Allows for more growth potential

Generalized Gnathostome Features:

Generalized Gnathostome Features The gill arches are more pronounced as is their gill musculature Hypobranchial muscles Two distinct nostrils and olfactory tracts Spiracle from first gill slit Three semicircular canals Addition of a new heart region Conus arteriosus Epaxial and hypaxial muscles Vertebral centra ( bodies) around notochord

Vertebrae Design:

Vertebrae Design Neural arch Dorsally positioned Protection for spinal cord Central elements formed around notochord Centrum Ribs Lateral bony elongations into segmental muscles Hemal Arch Ventral protection for caudal vessels Caudal regions

Fins :

Fins Propulsive force Tail fins for thrust Heterocercal caudal fin Dorsal and anal fins control for roll and yaw Paired fins control for pitch and for braking Some specialization for thrust Skates and rays

Fins :

Fins Additional specializations Spines for protection Poisonous glands Color for mating

Teeth Formations:

Teeth Formations Cartilaginous fish have tooth whorls Form in the skin Continually replaced Bony fish have teeth embedded in the bone Pleurodonts – tooth shelf Acrodonts – fused to jaw bone Theocodonts – set in sockets

Transitions to Jaws:

Transitions to Jaws Step wise evolution to jaws Initial adaptations for increased respiration Needed for increased activity Hinged gill arches created a sucking action Also required elaborate muscles

Transitions to Jaws:

Transitions to Jaws Inhalations had arches straightening Opened the pharynx Exhalations has arches bent Forces water back across gills As the muscles strengthened the mandible became larger

Transitions to Jaws:

Transitions to Jaws Starts with modifications to anterior gill arches 1 st arch (aka mandibular) gives rise to upper and lower jaws 2 nd arch (aka hyoid ) Bony attachment for hypobranchial muscles

Transitions to Jaws:

Transitions to Jaws Why use the mandibular arch structures for increased ventilation? Same innervation Means all respiratory efforts linked by same neural circuits


Locomotion Musculoskeletal Systems Pg 81-83 , 141-145,

Buoyancy :

Buoyancy One major factor of life in water is adjusting for buoyancy Use air to adjust vertical positioning Use swim bladders Smooth walled “lungs” NOT respiratory structures

Buoyancy :

Buoyancy Most Bony fish are neutrally buoyant Don’t need to swim to stay in vertical position at rest Slight pectoral and tail fin motion to counteract motion of water thru gills Well developed swim bladders

Swim Bladder:

Swim Bladder Positioned between peritoneal cavity and vertebral column 5-7 % of total body volume Smaller in sea water fishes (salt water is denser so smaller bladder needed) Walls of collagen and impermeable to gases

Swim Bladder:

Swim Bladder As a fish changes position the external forces cause the fish to alter the bladder Deeper water = increased pressure = decrease bladder size = reduced buoyancy To return to neutral buoyancy at different depths the fish alters gas volume

Adjusting Buoyancy:

Adjusting Buoyancy Some fish retain a connection between the bladder and the gut Pneumatic duct Physostomous Gulp air at surface to fill and burp air to release Goldfish, minnows

Adjusting Buoyancy:

Adjusting Buoyancy Physoclistic fish are more derived Gas is secreted into the bladder Gas gland on the ventral floor of bladder Associated with a system of vessels Rete mirabile Gland extracts gas from blood and moves it against pressure gradient

Adjusting Buoyancy:

Adjusting Buoyancy Gland first acidifies the blood in the vessels Lactic acid and CO 2 Hemoglobin releases O 2 Concentration builds in the rete mirabile until pressure is greater than in the gland To readjust the fish uses the ovale Muscular valve on dorsal side Increases local pressure to force gas back into blood

Deep Sea Bony Fishes:

Deep Sea Bony Fishes Use body fat and oils in inside the swim bladder Those that move over larger vertical distances use oils more than swim bladders

Buoyancy in Cartilaginous Fish :

Buoyancy in Cartilaginous Fish No swim bladders Use fat content in liver The lower they tend to live the less fat in their livers – negative buoyancy Also use compounds in blood Urea, trimethylamine oxide and chloride ions contribute to positive buoyancy

Aquatic Mammals:

Aquatic Mammals Must return to the surface for air Can’t hover at one depth Those who experience deep dives must guard against “decompression sickness Collapsible lungs prevent nitrogen from entering the blood stream

Locomotion in Water:

Locomotion in Water A series of anterior-to-posterior contractions on one side Relaxation on opposite side Bend moves back Body oscillates from side to side

Locomotion in Water:

Locomotion in Water Water behind the bend is pushed Gives forward thrust Lateral lift is negated by side-to-side changes

Locomotion in Water:

Locomotion in Water Most movements are confined to posterior region of the fish Anguilliform – whole body undulations Carangiform – undulations in cadual half Ostraciiform – hard bodies, only caudal fin moves


Obstacles Gravity and drag Drag is friction from water and the tendency to Pitch and Yaw Gravity is the downward push of water Swim bladders, pectoral fins

Drag and Thrust:

Drag and Thrust Anguilliform and carangiform fish can increase frequency of undulations Eels long body a hindrance Too flexible Tuna faster Shorter, less flexible, force more concentrate in back Caudal peduncle

Other Adaptations:

Other Adaptations Some fish DO NOT flex body Move fins Dorsal fin oscillations – Amiiform motion Anal fin oscillations – Gymnotiform motion Balistiform fish use both fins Labriform motion – uses rowing motion with Pectoral fins Rajiform anterior- posterior undulations of pec . fins

Improving Thrust:

Improving Thrust Two types of drag Viscous drag Fish body and water Constant over all speeds Body doesn’t change Inertial drag Pressure differences due to water displacement Increases with speed

Improving Thrust:

Improving Thrust Thin bodies have high viscous drag Surface area too large in relation to muscle mass Thick bodies too much inertial drag Too much water displaced Tear drop shape is JUST RIGHT

Improving Thrust:

Improving Thrust Best if the thickness of the body is ~25% of body length Teardrop morphology means the thickest part is ~ 1/3 the length back from the anterior end

Optimal Body Plan:

Optimal Body Plan

Other Modifications:

Other Modifications Caudal peduncle alterations Due to plane of oscillations Dorso -ventral narrowing Lateral narrowing in aquatic mammals

Other Modifications:

Other Modifications Caudal fin shapes Sickle shaped Retains the teardrop shape in cross section Reduces the drag across the surface

Other Modifications:

Other Modifications Deep peduncles Trout, minnows Laterally compressed Change the shape of caudal fin Spread or compress Stiffen or relax portions Burst swimmers Startle reflex

Appendicular Skeleton:

Appendicular Skeleton Paired fins and the girdle that links them to the axial skeletons Girdle only minor support role Mostly for anchoring branchial muscles Proximal regions are the pterygiophores Basal elements – enlarged, close to girdle Radial elements extend to the distal aspects Distal regions are the ceratotrichia Keratinized rods

Fin Strucutre:

Fin Strucutre Metapterygial – blunt proximal basals Located posteriorly Archipterygial fins – basals run down the midline Radials project anteriorly ( preaxial ) and posteriorly ( postaxially )

Theory on Origins:

Theory on Origins Gill arch theory The pectoral girdles arose from a posterior gill arch Gill rays extend and proliferate Archipterygial fins first Doesn’t explains pelvic girdles Doesn’t explain dermal bone in girdle bone Distinct embryology between gills and limbs WRONG

Fin Fold Theory:

Fin Fold Theory Origins in a paired ventral fins Single stabilizer role Pectoral and pelvis regions arose simultaneously Recapitulated in shark embryology Two regions specialized Basal and ray endoskeletons for support and muscle attachments

Fin Fold Theory:

Fin Fold Theory Molecular support for Fin fold theory Engrailed- 1 expression along ventral body regions T-box gene specializes fins Homoedomain containing gene Organisms with lateral ventral folds express single T-Box gene Amphioxus Gene duplication event to give 2 Tbx genes Acquisition of Sonic hedge hog expression allows for polarization Proximal-distal Anterior- posterior Tbx Tbx 4 Tbx 5 shh shh

Locomotion on Land :

Locomotion on Land Pgs 171-178

Land :

Land Major difference is gravity Skeleton must be able to support the body weight Density of water allows fish to push off Pushing off air not the same Limbs for backward force against some substrate

Bone :

Bone Rigid enough to support Remodels to adjust to demands of life Activity builds bone Inactivity = bone resorption Repair stress induced damage

Haversian System:

Haversian System Amniote bone arranged in Haversian systems Concentric layers around central vessels External regions of a bone is dense compact bone Central regions lighter “spongy” cancellous bone Is dense all the way through too heavy to move

Movable Articulations:

Movable Articulations Gravity means where two bone meet has to be modified Ends of bones mostly cancellous bone Epiphysis Covered with hyaline cartilage Reduces friction Space enclosed in a fibrous capsule Lined with synovial membrane/fluid

Axial Skeleton:

Axial Skeleton Processes project cranially and caudally Pre and post zygapophyses Interlocking Resists torsion Resists compression

Axial skeleton:

Axial skeleton Interlocking vertebrae act like a suspension bridge Carry weight of viscera on land Aquatic mammals have lost prominent zygapophyses

Free Moving Necks:

Free Moving Necks Bony fish have opercular bones Protect the gill region Anchor the pectoral girdle to cranium Fish can’t turn their heads Tetrapods have lost connection to operculum


Cervical Cervical vertebrae support muscle attachment to head motion First 2 vertebrae are most special Atlas articulates with the cranium Dorsal ventral flexion and extension Axis articulates with the atlas Pivot point


Ribs Trunk vertebrae have ribs Mammals ribs restricted to the thoracic region Caudal trunk vertebrae called lumbar Tetrapod ribs sturdier than fishes Stiffened trunk before axial muscles developed for posture

Axial Muscles:

Axial Muscles Primitive tetrapods use axial muscles for motility More derived use appendicular muscles for locomotion No longer just for motility Postural support Skeleton would buckle Ventilation

Epaxial Muscles:

Epaxial Muscles Three distinct layers Very Deep layers control alignment of the vertebral column Deep Middle layers control smooth extension of vertebral column Superficial Middle layers are respiratory Very superficial for limb

Axial Muscles:

Axial Muscles Primitive tetrapods use axial muscles for motility More derived use appendicular muscles for locomotion No longer just for motility Postural support Skeleton would buckle Ventilation

Epaxial Muscles:

Epaxial Muscles Three distinct layers Very Deep layers control alignment of the vertebral column Deep Middle layers control smooth extension of vertebral column Superficial Middle layers are respiratory Very superficial for limb

Hypaxial muscles:

Hypaxial muscles In fish there are two layers External and Internal obliques Tetrapods add a third Transverse abdominals Original function for exhalation in amphibians But also used for locomotion in some

Hypaxial Abdominal Muscles :

Hypaxial Abdominal Muscles Rectus abdominus Spans region from the pectoral to pelvic girdle Postural in nature Opposes the action of the epaxial extensors Particularly important in Bipedal locomotion

Hypaxial Thoracic Cage Muscles:

Hypaxial Thoracic Cage Muscles

Incompatible Functions:

Incompatible Functions Early tetrapods used body wall muscles for locomotion and respirations Limbs not positioned efficiently Straight out at sides Derived tetrapods adjust limb position Pull under trunk More efficient locomotion Better ventilation

Appendicular Skeleton:

Appendicular Skeleton Sharks and Boney fish Pectoral girdle is simple Single bone scapulocoracoid Attached to opercular bones and cranium Pelvic girdle Puboischiatic plate NOT attached to the vertebral column

Basic Design of Tetrapod limb:

Basic Design of Tetrapod limb Fan like basal elements proximally Mid positioned radial structures Ray-like strucutres broadening the base of the webbed fin

Basic Design of Tetrapod limb:

Basic Design of Tetrapod limb Limb girdle plus 5 elements Jointed limbs Forward pointing knee Backward pointing elbow Feet are for frictional contact in early tetrapods Amniotes use for propulsion Complex hinges in wrist/ankle

Limb Girdles:

Limb Girdles Pelvic Girdle fused to the sacral vertebrae Three fused bones on each side Ischium Ilium –connects directly Pubis Pectoral girdle free from the dermal skull Scapula and coracoid No attachment to the vertebrae Pectoral muscle Clavicle to sternum in some Some posterior dermal bone are incorporated into the girdle Clavicle and interclavicles

Moving through Air on Land:

Moving through Air on Land Have to generate friction Feet and ground More energetically expensive than water or air travel Diagonal pairs of limbs moving together Undulations Very primitive form in gnathostomes as some sharks do

Moving through Air on Land:

Moving through Air on Land Less derived amphibians mostly use body wall to achieve Lizards come to use limbs more Jumping, swimming very derived specializations

Moving through Air on Land:

Moving through Air on Land Walk has each leg moving independently In succession Three on the ground Trot is faster uses alternating diagonal limbs Bound jump off hind legs and land on forelegs Mammal characteristic Flexion of vertebral column Gallop is a modified bound All feet off ground Back limbs poised for next leap Richocet is the bipedal hop

Avian Specializations to Locomotion:

Avian Specializations to Locomotion Pg 439-460

Avian Specializations:

Avian Specializations Flight imposes a maximum size on a bird Bigger need increased power for takeoff Double size = 2.25fold power increase Proportions of total body mass remain constant Flight muscle percentages even 1.59fold from flight muscle changes Remainder from increases in “runway” time

Skeletal Modifications:

Skeletal Modifications Skeleton is NOT lighter Mass is differently distributed Many bone are pneumatic Filled with airy chambers Skulls are very light

Skeletal Modifications:

Skeletal Modifications Most of mass in hind limbs Proportionally heavier than a mammals Thoracic vertebrae are bound with strong ligaments Often ossified

Skeletal Modifications:

Skeletal Modifications Pelvic girdle drastically different Elongated Ilium, Ischium are flattened sheets of bone Posterior trunk vertebrae have fused 10-23 Synsacrum Caudal vertebrae are short Capped with a fused pygostyle

Skeletal Modifications:

Skeletal Modifications Mobility along axial skeleton is restricted to only a couple of regions Cervical region Joint between the thoracic region and the synsacrum Base of the tail

Skeletal Modifications:

Skeletal Modifications Very large keel shaped sternum Attachment points for the expanded flight muscles Scapula extends back over the ribs Coracoid is fused with the sternum Clavicles fuse at mid-line to form the furcula (wishbone)

Flight Muscles:

Flight Muscles Pectoral muscles can account for 20% of muscle mass Attaches to the humerus distal and ventrally Down stroke Deep supracoracoideus muscle Attached to humerus more proximally and dorsally Power upstroke

Skeletal Modifications:

Skeletal Modifications Hind foot is elongated Distal tarsals and metatarsals are fused to form a single long bone Tarsometatarsus (2) Proximal tarsals and tibia is fused Tibiotarsus (3) Ankle joint is positioned proximally ankle

Hindlimb :

Hindlimb Very adapted for different purposes Perching birds - anisodactyl All four toes free 3 forward; 1 back Passerine birds Zygodactylous – perching/climbing verticle surfaces 2 and 2 Woodpeckers

Hindlimb :

Hindlimb Walking or running birds reduce toe number Ostrich Rhea Makes foot lighter and accommodates the physics of locomotion

Swimming Specializations:

Swimming Specializations Wide body Dense plummage Webbed or lobed feet Palmate and totipalmate webbing Independently acquired ~4 times

Avian Wing:

Avian Wing Acts as both an airfoil for lift and a propeller for forward thrust Changes the shape of the wing for hovering, takeoff, and land Cambered airfoil Dorsal surface is curved Air velocity is faster Lift from below Larger closer to the body to combat weight

Avian Wing:

Avian Wing Ends of the wing are angled up to increase the camber Increases the lift Turbulence reduced by adding the alula Region on main wing to split the air at forward edge

Avian Wing:

Avian Wing Turbulence over the wing tips are also a problem Minimize by lengthening the wing More wing area for lift Moves vortices away from body Tapering wing also helps Long thin wings Aspect ratio Wing length/wing width High ratios good

Avian wing:

Avian wing Wing load Ratio of body mass to wing area Smaller birds require less power so load is lighter But ratio also relates to flight patterns; Soarers versus flappers


Physics Downward force provides the thrust Mostly at the primary feathers Most of vertical motion Secondary feathers closer to the body and give lift


Physics Wings are movable and generate two forces over a wing flap Standard lift of the cambered shape Mostly secondary The wing tips tilt during the down stroke Shifts the force to a forward thrust Inner and outer wing forces added so that thrust is greater than drag and lift is at least = to body weight

Larger birds:

Larger birds Need to generate thrust on upswing as well Wing twisting at the wrist and elbow Primaries push against the air Tips form a figure 8 in the air

Power Upstroke:

Power Upstroke Muscle placement allows for the upstroke Deep supracoradoideus Origin on keel Tendon slings between the scapula, coracoid and furcula Dorsal humeral attachment Pulls up and rotates medially

Mammalian Musculoskeletal:

Mammalian Musculoskeletal Pg 530- 533

Long Bones:

Long Bones Determinant growth Quick increases to adult size Epiphyseal regions separate from shafts of the bone Separate centers of ossification Allows for growth in length Once adult length is reached the two regions fuse

Cranial features:

Cranial features Original dermal bones completely enclose the brain case Cheek bone forms Muscles of mastication well formed Temporalis Masseter digastrics Only animals that chew their food

Cranial features:

Cranial features Muscles of facial expression Superficial to mastication Derived from the muscles in the hyoid region Dorsal muscles Cranial nerve 7 innervation Same innervation as 2 nd arch muscles in boney fish

Post cranial Skeleton:

Post cranial Skeleton Upright posture Limbs positioned underneath Ankle joint is formed between the tibia and the tarsus Not in the tarsal region Hinge joint

Post cranial Skeleton:

Post cranial Skeleton Calcaneus bone Posterior extension forming the heel Attachment point for the gastrocnemius and soleus muscles 93% of plantar force during the gait cycle

Pelvic Girdle:

Pelvic Girdle Ilium is directed forward Femur has a laterally positioned Projection Greater trochanter Attachment for gluteal muscles Primary abductors, extensors of lower limb

Axial Skeleton:

Axial Skeleton Seven vertebrae in cervical region Final derivation of the atlas-axis articulation Full range of motion at head Ribs restricted to the thoracic region

Axial Skeleton:

Axial Skeleton Lumbar zygapophyseal joints allow only dorsal ventral flexion Bigger transverse processes longer for Longissimus muscle attachment Lateral rotation Allows for lying on side Suckling

Mammalian Specializations for Locomotion:

Mammalian Specializations for Locomotion Pg. 569 - 575

Small mammal locomotion:

Small mammal locomotion Small mammals bound and scramble Back is curved ventrally Flexion Limbs are all partially flexed Zig-zag patterns Ideal for small body size running on irregular surfaces

Large Mammal Locomotion:

Large Mammal Locomotion Energy cost to locomotion in large animals Number of strides to cross a given distance Long legs Few strides Lever arms for locomotor muscles ; triceps and gastrocnemius Favors speed

Limb Anatomy in Cursorial Mammals:

Limb Anatomy in Cursorial Mammals Specialized for running Lower limbs elongated middle components only Proximal bones not longer Phalanges not longer ‘Humerus’ ‘femur’ ‘forearm’ ‘wrist’

Cursorial Mammals:

Cursorial Mammals Limb musculature is positioned proximally Only long tendons in lower portions of limb Keeps the weight of the lower limb down Helps acceleration of limbs during galloping From zero to faster than forward motion Long tendons help with energy costs Store and release elastic energy with each stride Even in humans

Cursorial Limbs:

Cursorial Limbs Limbs move in one plane Anterior- posterior (for and aft) Wrist and ankle joint modifications Small or no clavicle No forelimb supination Number of digits reduced Limb weight Stopping power Carnivores lose first digit and compact rest Artiodactyls - 2 or 4 toes Pigs or deer Perissodactyl – 1 or 3 toes Horse , rhino

Evolution of Cursorial limb :

Evolution of Cursorial limb Predator prey relationships? Longer and faster strides meant an advantage For both But fossil record does not show co-evolution Really because same anatomy better at trots Changes in ecology Ungulates Forage further for food

Evolution of Cursorial limb :

Evolution of Cursorial limb Why did ungulates achieve better locomotion adaptations? Because they don’t move faster than carnivores Pig v lion Disproportionate body mass Gut and contents up to 40% of mass Legs evolved long and thin to counteract weight during locomotion Elastic recoil Wider base with longer stance

Fossorial Motion:

Fossorial Motion Diggers Mammals that follow prey down hole have elongate body plans Ferrets Limbs maximized for power, not speed Long olecranon process More lift from triceps Short forearm Power lever

Foot structure :

Foot structure Diggers have plantigrade foot orientation Large heel for power Short metatarsals All 5 digits Digitigrade animals- dogs Transition to full cursorial motion Phalanges on ground Metatarsals and leg long and thin Unguligrade feet – pig Digits compacted or lost Long metatarsals

Aquatic Mammals:

Aquatic Mammals Semiaquatic mammals not much is different More paddle-like limbs Evolved several times Monotremes - platypus Marsupials – water opposums Rodentia – beavers Carnivore – polar bears Artiodactyl - hippopotomus

Aquatic Mammals:

Aquatic Mammals Fully aquatic mammals evolved three times Cetacea – whales, dolphins Sirenia – manatee Carnivora – sea lions, seals

Aquatic Mammals:

Aquatic Mammals Limbs used for paraxial swimming Fairly inefficient Short proximal regions of limbs Motion restricted to shoulder Cetaceans and sirenians have lost hind limbs

Aquatic Mammals:

Aquatic Mammals Compensate with dorsal-ventral undulations Modified vertebral column Trunk region lost the zygapophyseal joints Compressed cervical vertebrae Reduces motion anterior region No sacral vertebrae Long tail


Bipedality Pg653-656

Slide 257:


Homonoids All modern Hominoids can stand erect Only humans use as primary means of locomotion Alterations to pelvis Take on brunt of weight bearing Thicker, less elongate Ilium basin shaped Two arcs for support

Hip Joint:

Hip Joint Femur specialized Head set away from shaft at angle Angled joint at the acetabulum Angle of inclination Less obtuse with age Less in women Increases arc Better distribution Increases range of motion

Vertebral Column Curvatures:

Vertebral Column Curvatures Thoracic and Sacral Kyphoses Concave ventrally Primary curvatures Determined by shape of vertebral body Cervical and Lumbar Lordoses Concave dorsally Secondary curvatures Determined by shape of IV disc

Knee Positions:

Knee Positions Knock-Kneed stance Torsion angle measures the alignment of femur with the tibia Increases range of motion Greater in females because the pelvis is wider Women more prone to knee injuries

Foot Modifications:

Foot Modifications Big toe no longer opposable Digits are shorter Plantar surface broader Increased surface area

Arches of the Foot:

Arches of the Foot Arches eliminate tensile stress Convert all force to compressive stress Longitudinal and transverse arches Distribute weight Shock absorbers Springboards for walking Supported by flexible structures

Arches of the Foot:

Arches of the Foot Long arches have a medial and lateral aspect Medial is higher and more important Lateral is flatter

Arches of the Foot:

Arches of the Foot Passive and dynamic support Passive from the plantar aponeurosis and the ligaments of the foot Dynamic from muscles and long tendons

Trunk modifications:

Trunk modifications Barrel shaped rib cage Not funnel Allows for a distinct waist Waist allows greater rotation of pelvis No involvement of upper body

Why Evolve Bipedality:

Why Evolve Bipedality Predator avoidance See over high objects Carrying objects Thermoregulation Surface area of back

Bipedal Running:

Bipedal Running Several skeletal adaptations needed for bipedal running Longer leg Increased stride Long achilles tendon Elastic energy

Bipedal Running:

Bipedal Running Basin like pelvis driven by larger gluteal muscles Needed more for running than walking

Bipedal Running:

Bipedal Running Distance between shoulders and head Rhomboids Chimp to skull Human to vertebrae Trapezius Chimp to skull Human to nuchal ligament Nuchal ligament

Respiratory Systems and Gas Exchangers:

Respiratory Systems and Gas Exchangers

Gas Transport:

Gas Transport Two functional systems Respiratory to handle diffusion of O 2 from environment Air or water Cardiovascular to handle distribution of O 2 to deeper regions Physics of diffusion governs exchange at both sites

Slide 273:

Boyle’s Law The volume of a gas (O 2 , CO 2 ) is inversely proportional to it’s pressure

Slide 274:

Dalton’s Law of Partial Pressures The total pressure of a mixture of gases (O 2 , CO 2 ) is equal to the sum of the pressures of each gas

Slide 275:

Henry’s Law The amount of gas (O 2 , CO 2 ) dissolved in a liquid is directly proportional to the pressure of the gas in the air

Slide 276:

Why do vertebrates need respiratory gas exchangers and cardiovascular systems? Why can’t gas just pass through the skin and tissues?

Fick’s First Law of Diffusion:

Fick’s First Law of Diffusion Rate of Diffusion is proportional to Area x Concentration/ Distance Rate = dm/ dt = D x A x dC / dx A= area available for diffusion C = concentration of substance X = distance for diffusion D = diffusion coefficient

Diffusion Coefficients:

Diffusion Coefficients Properties Units Water Air (1atm) Water/Air O 2 Diff Coeff . cm 2 /s 0.000025 0.198 1/7920 CO 2 Diff Coeff . cm 2 /s 0.000018 0.155 1/8600 A typical vertebrate organism is too thick for gas exchange to occur via simple diffusion Most tissues would experience significant hypoxia (low O2) and hypercapnia (high CO2) Must bring fluids (blood/air/water) close enough for diffusion to happen naturally

Types of Exchange Structures:

Types of Exchange Structures Gills Tissue evaginates at body surface Capillaries extend through folds Lungs Tissue invaginates deep into animal Capillaries between/around folds Tracheae Branched tubes into deep tissue No circulation simple diffusion

Models of Gas Exchange:

Models of Gas Exchange Open flow Best example is Amphibian skin No inspiratory/ expiratory change in gas pressure Concentration change in blood vessels

Models of Gas Exchange:

Models of Gas Exchange Countercurrent flow Blood flow is opposite of ventilatory fluid flow Best because the perfusing fluid will constantly take O2 Even higher arterial concentrations will be lower than the Inspiratory gas pressure

Models of Gas Exchange:

Models of Gas Exchange Crosscurrent flow Bird lungs come closest Perfusate will equilibrate to 50% of incoming

Models of Gas Exchange:

Models of Gas Exchange Uniform Pool flow Mammalian lungs Similar to open flow system The alveoli are maintained at a steady pressure by diffusion Transport driven by changes in vessel concentrations


Fish Pgs 77-81

Oxygen Solubility in water:

Oxygen Solubility in water Oxygen is not very soluble in water CO 2 is much more soluble Means very difficult for fish to extract O 2 from liquid media

Ventilation in Fish:

Ventilation in Fish Water is very viscous Energetically expensive to breath Need to push a lot of water over gills to satisfy needs Maximize exchange by using counter current mode

Unidirectional Flow:

Unidirectional Flow Water always moved one way Mouth Buccal cavity Pumped over gills Collected in opercular cavity Empty out operculum

Countercurrent Flow in Lamellae:

Countercurrent Flow in Lamellae Afferent vessels = low O2 Capillaries carry blood through lamellae Buccal pumping pushing water between lamellae

Countercurrent Flow:

Countercurrent Flow Maximizes the uptake of O 2 Blood always getting O 2 because the water levels are always higher

Positive Pressure Ventilation:

Positive Pressure Ventilation

Activity v Gill Structure:

Activity v Gill Structure # of lamellae, Area, O 2 capacity match the activity level of organism

RAM Ventilation:

RAM Ventilation Some fish employ Buccal and RAM type ventilation Swimming with mouth open no pumping Some sharks, mackerel, tuna Occurs when the fish is more active Rates of buccal pumping go down No stop to gas exchange

Swim Bladder:

Swim Bladder Positioned between peritoneal cavity and vertebral column 5-7 % of total body volume Smaller in sea water fishes (salt water is denser so smaller bladder needed) Walls of collagen and impermeable to gases

Adjusting Buoyancy:

Adjusting Buoyancy Physoclistic fish are more derived Gas is secreted into the bladder Gas gland on the ventral floor of bladder Associated with a system of vessels Rete mirabile Gland extracts gas from blood and moves it against pressure gradient

Adjusting Buoyancy:

Adjusting Buoyancy Some fish retain a connection between the bladder and the gut Pneumatic duct Physostomous Gulp air at surface to fill and burp air to release Goldfish, minnows

Derived Swim Bladders:

Derived Swim Bladders Some fish have adapted swim bladders as gas exchangers Shallow, stagnant water Warm water Hold less oxygen Physostomic fish - gulpers

Air Breathing Fish :

Air Breathing Fish Two part cycle Air into buccal cavity Moves into anterior gas bladder Air from posterior gas bladder is released Water enters the buccal cavity Pressure forces AGB air into PGB Air in respiratory gas bladder exchanges


Lungfish Lobed finned fish Africa, Australia and South America Gills are less efficient Seasonal drying Estivation Summer sleep 1/60 th of normal metabolic rate


Lungfish Gills and lungs Lungs homologous to tetrapods Ventral out-pocketing of pharynx Traditional swim bladders are dorsal Some CO2 exchange from gills when air breathing


Lungfish Anterior Portions of the lung contains septum Heavy vascular component Gas exchange Circulation through gills is changed to prevent water loss


Amphibian 250-255

Amphibian Modifications:

Amphibian Modifications Have numerous adaptations External gills Internal gills Mouth or cloacal exchangers Cutaneous exchange Lungs

Frog lungs:

Frog lungs Ventral outpocketings Simple sacs Minimum internal septation Vessel network on the outside Positive pressure ventilation

Buccal Pumping:

Buccal Pumping Two part cycle Like air breathing fish Buccal filling Glottis is closed Buccal constriction and glottis open pushes new air into lungs Exhalation just prior to next cycle

Buccal Dilation :

Buccal Dilation Buccal dilation used for other purposes vocalization Not always for ventilation Series of buccal movements without lung inflation Intermittent respiration

Cutaneous Respiration:

Cutaneous Respiration Frog skin only a few cells thick No cornified layer Blood vessels VERY close Facilitates transcutaneous gas exchange

O2 movement through Skin:

O 2 movement through Skin Minimal Lungs responsible for most of O 2 exchange Air breathing More efficient than moving from water Solubility issues

CO2 movement through Skin:

CO 2 movement through Skin CO 2 more soluble in water Has a better diffusion rate Will leave the skin faster Most of transcutaneous exchange is release of CO 2 from blood

Skin Exchange Rates Vary:

Skin Exchange Rates Vary Different species use transcutaneous exchange to differing degrees Frog move mostly CO 2 Salamanders move both gases equally


Reptiles 270-279

Phylogeny of Respiration:

Phylogeny of Respiration Increased septation of lung Gastralia appear Rib like structures in abdominal region Axial and rib muscles needed for negative pressure

Lung Architecture:

Lung Architecture Reptilian lungs are faveolar Central chamber Lateral septation Synapsid lungs are alveolar Branched conducting tube Terminal respiratory membranes Both normally use tidal ventilation and negative pressure


Gastralia Bony rods in ventral body wall V-shaped with Apex anteriorly Attached to body wall muscles Sequential contraction and relaxation Inspiration and exhalation Crocodilian


Turtles How to move lungs encased in a hard shell? Move the viscera Two membranes guard the body cavity Anterior and posterior limiting membranes Muscles attach here and to limb girdles Extension of limbs “opens” cavity Lowers pressure Air in

Hepatic Piston:

Hepatic Piston Crocidilians Use ribs and viscera movement Gastralia still present Rectus abdominus and ischiopubic muscles Hepatic piston Diaphragmatic muscle moves liver posteriorly Inspiration Relaxation = exhalation

Gas Transport:

Gas Transport

Respiratory Pigments:

Respiratory Pigments Blood is mostly water O 2 not very soluble in water How do we hold it in blood and move it around?? Animal Physiology 2 nd ed. Fig. 23.4

Respiratory Pigments:

Respiratory Pigments Lots of different pigments used throughout the animal kingdom The chordates use only hemoglobins and myoglobin


Myoglobin Globin Protein with a heme pigment Iron molecule holds oxygen Monomer

Mammalian Hemoglobin:

Mammalian Hemoglobin Adult Hemoglobin is a Tetrameric protein Each protein chain has 1 Heme group Each can hold 1 molecular Oxygen (O 2 )

p50 saturation:

p50 saturation As pressure of O 2 increases the globins get saturated P 50 =Pressure of oxygen where 50% of the oxygen is bound to the transport proteins Myoglobin has lower P 50 Binds O 2 better at lower pressures

Consequences of P50 values:

Consequences of P 50 values

Things that Drive Dissociation:

Things that Drive Dissociation As we use oxygen in the tissues the pressure goes down Oxygen comes off pigments The faster we use the faster it comes off Why??

Bohr Effects:

Bohr Effects Local Increases in Carbon Dioxide can cause O 2 to come off Hb Acidifies the blood Carbonic acid Direct acidification of blood has same effect

How to Lower Affinity:

How to Lower Affinity Lowered PO 2 Levels in periphery will drive dissociation Metabolism at tissue level means heat, CO 2 and acid levels increase Means O 2 comes off Hb faster Free to diffuse to cells

Types of Human Hemoglobin:

Types of Human Hemoglobin Two gene clusters Alpha on Chr 16 Beta on Chr 11 Tetramers change as we move through early development Temporal expression matched orientation in cluster Embryonic hemoglobins Fetal hemoglobin Adult hemoglobins gower 1- zeta(2), epsilon(2) gower 2- alpha(2), epsilon (2) Portland- zeta(2), gamma (2) hemoglobin F- alpha(2), gamma(2) hemoglobin A- alpha(2), beta(2) hemoglobin A2- alpha(2), delta(2)

Function of Hemoglobin Isoforms:

Function of Hemoglobin Isoforms Embryonic and fetal forms are better O 2 carriers Picking up blood from the placenta not the lungs Higher rates of metabolism in developing tissues Shifted to adult hemoglobin by 3 months post natal

Packaging of Hemoglobin:

Packaging of Hemoglobin Hemoglobin is not free in the blood Packaged into red blood cells Reduces the viscosity of blood Most vertebrates have nucleated RBCs

Packaging of Hemoglobin:

Packaging of Hemoglobin Mammalian RBCs are anucleated when mature Theories include More room for hemoglobin Makes them bendable for moving through small capillaries But other species have small capillaries Bone marrow means quicker supply so no need for repair

Cardiovascular System:

Cardiovascular System 183-187 250-253 315-316

Organizational Requirements:

Organizational Requirements Need large surface area for O 2 exchange into system Rapid means of transport to tissues Inhibition of diffusion during transport Large surface area for diffusion to tissues Return vessels Boron & Boulpaep 2004. Medical Physiology

Vertebrate Circulatory Circuits:

Vertebrate Circulatory Circuits Closed system Pump heart Conduction vessels Branched arterial and venous networks Capillaries

Vertebrate Circulatory Circuits:

Vertebrate Circulatory Circuits Heart Used to establish pressure gradient Fluid will always flow down Vertebrate hearts are pulsatile compliance chambers Prominent back-flow valves Endogenous rhythms

Vertebrate Circulatory Circuits:

Vertebrate Circulatory Circuits Conduction vessels Arteries and Veins Large radius for decreased resistance Easier transport/less work by heart Thicker walls Decreased diffusion while in transport Numerous branches for distribution Anastomoses for control at tissue

Vertebrate Circulatory Circuits:

Vertebrate Circulatory Circuits Capillary beds Large number Increased surface area for maximum diffusion Very small diameter Around 10u Very short Small diameter means increased resistance Short vessels needed or blood wouldn’t flow



Ancestral Heart :

Ancestral Heart Three main chambers In series Conus arteriosus is elastic and contractile Extra pumping mechanism to facilitate emptying Enlarges to the Bulbus cordis in more derived fish Real 4 th chamber

Hagfish Circulation:

Hagfish Circulation Conus not enough to maintain pressure Accessory hearts needed Caudal heart in the tail region to move blood through cardinal veins Portal heart to pump through liver

Role of Bulbus Cordis :

Role of Bulbus Cordis Ventricle pressure very high at contraction Pressure drops on relaxation This would stop blood flow through ventral aorta for a time

Role of Bulbus Cordis :

Role of Bulbus Cordis Contraction of bulbus as blood leaves Means pressure always higher than in aorta Blood always flows in correct direction . (Modified from Waterman et al. 1971; Stevens et al. 1972.)

Teleost and Elasmobranch Plan:

Teleost and Elasmobranch Plan Tubular heart with 4 chambers in series Sinus Venosus Atrium Ventricle Bulbus (conus) Arteriosus

Role of the Pericardium:

Role of the Pericardium Pericardium surrounds the heart Strong and inflexible Means pressure changes as chambers contract Aids in atrial filling

Teleost and Elasmobranch Plan:

Teleost and Elasmobranch Plan Flows into the ventral aorta towards the gills Afferent branchial arteries carry low O 2 blood to gills Efferent branchial arteries take high O 2 blood to dorsal aorta Eckert Anim Phys 1997

Modifications for Air Breathers:

Modifications for Air Breathers Blood goes thru some gills to air organs Back to heart via cardinal veins Repumped to dorsal aorta via modified gill pathway May be mixed O 2 Eckert Anim Phys 1997

Lung Fish:

Lung Fish Gill arches 5 and 6 have gill structures Low O 2 blood goes through and picks up oxygen Leaves to body through vasomotor segment

Lung Fish:

Lung Fish If Low Oxygen coming out of gills blood shunted to lungs Gas exchanged and moves back to heart

Lung Fish Heart:

Lung Fish Heart Atrium and ventricle are partially divided Keeps mixing low Sinus venosus goes in the right side Blood from lungs to left side

Lung Fish Heart:

Lung Fish Heart Conus has a spiral fold separating it into two channels Directs blood from right to lungs/gills Via 5 th and 6 th arch Blood from left to periphery Via 3 rd and 4 th



Frog Heart:

Frog Heart Partitioned atrium Complete in anurans Numerous ventricular trabeculae Prevents blood mixing Spiral valve Alternately blocks entrances to the outflow track Shortened aorta Valve means higher resistance Shorter is better Eckert Anim Phys 1997

Patterns of Blood Flow/Theories:

Patterns of Blood Flow/Theories Sequential loading of ventricle Deoxy . then Oxy. Ventricular contraction (systole) moves from left to right J.S. Turner EFB 462 Animal Physiology: Environmental & Ecological

Patterns of blood flow/Theories:

Patterns of blood flow/Theories Trabeculae in ventricle wall Segmentation of blood streams Differential O2 pressures Higher settles deeper in ventricle

Larval Circulation:

Larval Circulation Resembles fish more Gills to breathe Arches 3-5 still transmit to gills After metamorphosis pathways modified 3 becomes internal carotid 4 feed into dorsal aorta 5 degenerates 6 becomes the pulmonary arteries



Frog Heart:

Frog Heart Partitioned atrium Complete in anurans Numerous ventricular trabeculae Prevents blood mixing Spiral valve Alternately blocks entrances to the outflow track Shortened aorta Valve means higher resistance Shorter is better Eckert Anim Phys 1997

Patterns of Blood Flow/Theories:

Patterns of Blood Flow/Theories Sequential loading of ventricle Deoxy . then Oxy. Ventricular contraction (systole) moves from left to right J.S. Turner EFB 462 Animal Physiology: Environmental & Ecological

Patterns of blood flow/Theories:

Patterns of blood flow/Theories Trabeculae in ventricle wall Segmentation of blood streams Differential O 2 pressures Higher settles deeper in ventricle

Larval Circulation:

Larval Circulation Resembles fish more Gills to breathe Arches 3-5 still transmit to gills After metamorphosis pathways modified 3 becomes internal carotid 4 feed into dorsal aorta 5 degenerates 6 becomes the pulmonary arteries


Reptiles 279-280 312-314

Non Croc Reptilian Heart:

Non Croc Reptilian Heart Modifications in many of the species Support a more fully terrestrial life Higher metabolic rates Eckert Anim Phys 1997

Non Croc Reptilian Heart:

Non Croc Reptilian Heart Sinus venosa is reduced Atria completely separated Guarded by atrioventricular valves Eckert Anim Phys 1997

Non-Croc Reptilian Heart:

Non-Croc Reptilian Heart Ventricle partially compartmentalized Horizontal septum Muscular ridge Demarcates left and right ventricles Right called the cavum pulmonale Vertical septum divides left ventricle Cavum arteriosum Cavum venosum Eckert Anim Phys 1997

Non-Croc Reptilian Heart:

Non-Croc Reptilian Heart 3-4 main outflow vessels from the conus Pulmonary trunk To lungs 2-3 vessels off the cavum venosum Right and left aortic trunks Brachiocephalic artery (only sometimes off ventricle) Eckert Anim Phys 1997

Non-Croc Reptilian Hearts :

Non-Croc Reptilian Hearts Mixing of low and high O 2 blood will occur Minimized in various ways Based on whether they must hold break for various times Positioning the septa and outflow tracks

Non Croc Reptilian Hearts:

Non Croc Reptilian Hearts During relaxation atria empty to ventricles Blood from right atrium directed to C. pulmonale Relaxation of septum and opening of right AV valve

Non Croc Reptilian Hearts:

Non Croc Reptilian Hearts During systole interventricular septum is shifted Slight asynchrony in contraction of ventricle Right side first to shunt blood to lungs earlier.

Turtles (pg 312-314):

Turtles (pg 312-314) Adaptations which allow for a modified lung bypass Increased resistance in lung vasculature activates right-left intracardiac shunt Some low O 2 blood into systemic arterial flow

Turtles (pg 312-314):

Turtles (pg 312-314) Matches blood flow to ventilation in intermittent breathers in divers While not breathing no blood needs to go to lungs Wasteful of energy

Crocodilian Hearts:

Crocodilian Hearts Completely divided into 4 chambers Pulmonary trunk comes off the right ventricle Left aorta comes off the right ventricle Right aorta comes off the left ventricle

Crocodilian Hearts:

Crocodilian Hearts The left aorta protected by a valve at opening Two aorta are connected by a shunt Foramen of Panizza Operates as part of a bypass system when submerged

Crocodilian Hearts:

Crocodilian Hearts Air breathing Diving/apnea



Avian Heart:

Avian Heart Completely separate circulations Right side handles pulmonary Left side handles systemic Fully terrestrial All air breathing No bypasses

Avian Arterial Plan:

Avian Arterial Plan Very similar to mammalian Not homologous BUT closer to crocs Retains the right aortic artery

Adaptations for High Altitude Flight:

Adaptations for High Altitude Flight Some birds go to very high altitude Bar-headed geese Migrate over the Himalayas (9000m) Suffer hypoxia while at high metabolic rates

Adaptations for High Altitude Flight:

Adaptations for High Altitude Flight Changes at the tissue and cellular level More capillaries per muscle fibers Higher capillary density Muscle cell mitochondria closer to cell membranes O 2 easier diffusion from blood to tissues



Mammalian Heart:

Mammalian Heart Fully compartmentalized 4 chambers Right to pulmonary circulation Left to systemic circulation

Mammalian Heart:

Mammalian Heart Unidirectional flow Atria and ventricles separated by one way valves Left side mitral/bicuspid Right side tricuspid

Mammalian Heart:

Mammalian Heart Unidirectional flow Outflow tracks protected by semilunar valves Pulmonary Aortic



Cardiovascular Systems Functional Principles:

Cardiovascular Systems Functional Principles


Pacemakers All vertebrate hearts possess innate pacemakers Starts the electrical impulse Need to coordinate contractions Input from the CNS can modulate frequency of contractions


Pacemakers Sinoatrial Node Positioned in right atrium Base of the Superior vena cava Atrioventricular Node At AV valve on right side


Pacemakers SA node links to AV node by internodal fibers AV node sends impulses down septum and around walls Bundle of His Purkinje Fibers

Cardiac Muscle:

Cardiac Muscle Cells are branched Linked electrically Special gap junctions called intercalated discs If one cell is stimulated all will contract

Skeleton of the Heart:

Skeleton of the Heart Connective tissue rings Attachment for valves Disconnects the muscles of the atria from the ventricles Means ventricles contract after atria

Coordination :

Coordination SA node begins impulse Atria contract together Impulse reaches AV node Sends impulse out a tad slower


EKG Can measure the length and magnitude of impulse with EKG P-wave area measures atrial contraction Space is lag time until AV node fires QRS wave is ventricular contraction T-wave is ventricular relaxation

Flow through vessels:

Flow through vessels “ Ohmic ” flow relationships Current = V/R Flow = Pressure difference/ Resistance Q r P 1 P 2 Q P P R = - 1 2

Flow through vessels:

Flow through vessels R is proportional to the length R is inversely proportional to the Radius to the 4 th power Q r P 1 P 2 R g L r = × × × 8 4 h p

Flow through vessels:

Flow through vessels Long narrow vessels have greatly reduced flow Garden hoses Q r P 1 P 2 R g L r = × × × 8 4 h p

Anatomical Control :

Anatomical Control Long vessels have larger radii to reduce resistance The narrower the vessel the shorter it is Resistance is minimized and flow maintained

Anatomical Control:

Anatomical Control Arterioles set in parallel not series Flow into region always equal flow out

Physiological Control:

Physiological Control Control of flow through tissues Contraction and relaxation of arteriole smooth muscle Change flow to tissue based on metabolic requirements Arteriovenous anastomoses Shunts through capillary beds Change flow in response to pressure differential

Slide 403:

Smooth Muscle a.k.a Non-Striated Involuntary Long fibers, single enucleated cells, spindle shaped Loosely organized along a plane Organs, vessels Not linked electrically More complex control mechanisms

Smooth Muscle:

Smooth Muscle Contraction caused by numerous molecules All increase calcium levels Neurotransmitters Epinephrine, Norepinephrine Growth factors Endothelin Hormones Angiotensin II ANP

Smooth Muscle:

Smooth Muscle Relaxation from increases in cyclic nucleotides cGMP cAMP Neurotransmitters Epinephrine, Norepinephrine Gasses Nitric Oxide Hormones Atrial Natriuretic Peptide ANP



Gonads :

Gonads During development the gonads begin as undefined swelling in the mesoderm Indifferent gonad Contains a cortex and a medullary region Germ cells migrate into the gonads Sex hormones determine where they stop Females stop in the cortex Males germ cells stop in the medullary

Female Gonads:

Female Gonads Ovaries are protected by a covering Germ cells are surrounded by a supportive layer of follicle cells As a single oovum matures the area around it grows into a follicle

Female Gonads:

Female Gonads The mature oovum is released Picked up by the oviduct Transmitted out for external fertilization Fertilized internally and processed

Male Gonads:

Male Gonads Ovoid structures Thousands of seminiferous tubules Sperm manufacture Sperm collection Transmitted to a ductal system for release

Male Gonads:

Male Gonads Orientation with in the seminiferous standard Basal layers has stem cells Proliferative Complete meiosis as they move towards lumen

Urogenital System:

Urogenital System Includes the urinary/excretory systems Includes the genital/reproductive systems Often includes the development of the adrenal glands

Urogenital System:

Urogenital System Derived from the Intermediate Mesoderm During folding this mesenchyme pulled ventrally At closure of the body wall tissue forms a urogenital ridge along the dorsal body wall Two components to ridge Nephrogenic cord Gonadal ridge Extends from the cervical somites to the cloaca

Genital System:

Genital System There is a thickening of the tissue near the gonadal ridge Epithelial cells proliferate and form gonadal chords Subdivided to cortex and medulla The primordial germ cells migrate into indifferent gonads from yolk sac Populate the cords All gonads remain internal except in mammals

Sex Determination:

Sex Determination Female is usually the default Male phenotype requires instruction Y-chromosome Testes Determining Factors Under this influence the gonadal chords differentiate to the Seminiferous cords Differentiated Testes make testosterone Responsible for maleness

Genital Duct Systems:

Genital Duct Systems Both genders start with two ductal systems Mesonephric (archinephric) ducts Wollfian duct From the developing urinary system Paramesonephric duct Develops lateral to the nephric system Mullerian duct

Male Genital Duct Systems:

Male Genital Duct Systems Archinephric ducts remain in the male Proximal becomes the epididymis Distal becomes the vas deferens and ejaculatory duct Archinephric system degenerates in females

Male Genital Duct Systems:

Male Genital Duct Systems Male ducts arise because the testes makes testosterone Promotes the differentiation of the Wollfian system Also make Mullerian Inhibiting Substance (MIS) Blocks the formation of the Mullerian duct

Female Genital Duct Systems:

Female Genital Duct Systems In the absence of MIS Para mesonephric Ducts Lateral to mesonephric ducts and gonads Cranial ends are funnel shaped and open to the abdominal cavity Fimbriae of fallopian tubes Caudal ends empty into cloaca Sometimes fuse into uterovaginal primordium

Lamprey Reproduction Anatomy:

Lamprey Reproduction Anatomy Orientation of the gonads in less derived vertebrates Back wall of coelom Females 200,000 follicles develop at once Gametes released onto body cavity Ductal system Collected in cloaca

Shark Females:

Shark Females Sharks ( elasmobranchs ) often only one ovary develops Differentiation of Mullerian duct into four regions Funnel Shell gland ( nidamental gland) Isthmus Uterus

Teleost Females:

Teleost Females Some lack very complex ductal systems Salmonids Oocytes released, in large numbers, into body cavity Picked up by coelom Other teleosts have the mullerian ducts regress completely New oviduct are formed from peritonela folds

Tetrapod Females:

Tetrapod Females Amphibians have paired ovaries Standard oviductal system Ovaries are released for external fertilization In amniotes the mullerian system remains Muscular walls for transmission of fertilized ova Mucus membrane for support Specialized for fertilization methods Nidamental glands for creation of shell Partial midline fusion of tubes for placentals

Adaptations to Oviducts:

Adaptations to Oviducts

Male adaptations:

Male adaptations Non amniotic sperm mature in cycts or follicles All the sperm in the follicle mature at the same time Clonal maturation

Fish Adaptations in Males:

Fish Adaptations in Males In the Lamprey/hagfish there are no ductal systems Sperm empty into coelom and exit thru abdominal pores Male Sharks use the degenerated Mullerian ducts to move sperm Accessory urinary ducts Archinephric ducts are ONLY for urine In Teleosts the male ductal system doesn’t derive from Archinephric ducts Separate set up

Tetrapod Adaptations in Males:

Tetrapod Adaptations in Males As the archinephric kidneys become less important for urine production the ducts are repurposed Some amphibians ( necturus ) use the archinephric ducts for both urine and sperm Male Amniotes use the archinephric ducts EXCLUSIVELY for sperm Urine transmitted by the metanephric duct

Tetrapod Adaptations in Males:

Tetrapod Adaptations in Males Mammals often reposition the testes in scrotal sacs Cooling mechanism (?) 8 o C Internal Descend completely during mating season External (pre or post penile) Descend during development Move through the abdominal wall

Tetrapod Adaptations in Males:

Tetrapod Adaptations in Males Some mammals lack a scrotum Aquatic Mammals Hydrodynamics of swimming Testes are kept cool via a counter current vascular network

Egg Structure:

Egg Structure Cell membrane Encloses the nucleus and the cytoplasm Specialized proteins for sperm fusion and ion flow during fertilization

Egg Structure:

Egg Structure Fibrous Mat Surrounds the cell membrane Called Vitelline envelope in external fertilizers Attached to the cell membrane Specialized for species recognition during fertilization

Egg Structure:

Egg Structure Cortex Lies below the cell membrane Gel-like cytoplasm Globular actin stored here Microfilaments for early cytoplasmic divisions Microvilli for sperm entry

Egg Structure:

Egg Structure Cortex Granules lie just below plasma membrane Analogous to the acrosome of sperm Contains enzymes/proteins used to prevent polyspermy

Egg Structure:

Egg Structure Jelly Many species eggs are coated with an external jelly layer Used for either species- specific sperm attraction and/or activation

Egg Structure/Mammals:

Egg Structure/Mammals Fibrous Mat in Mammals In Mammals the fibrous mat called the Zona Pellucida Thick extracellular matrix layer separate from the cell membrane Surrounded by a layer of cells called a Cumulus Derived from the follicular cells after ovulation Layer adjacent to ovum is called the corona radiata

Egg Maturation:

Egg Maturation The Ploidy of the female pronucleus at fertilization is different depending on the species Some species are fully haploid at fertilization Sea Urchins Most mammalian oocytes are still diploid at fertilization Arrested at second metaphase Final stages of Meiosis are completed as sperm pronucleus is moving towards female nucleus

Sperm Maturation :

Sperm Maturation As the sperm develop in the testes most of organelles are lost Most of the cytoplasm is lost Only left with what is needed as very specialized structures

Sperm Maturation :

Sperm Maturation Haploid Nucleus becomes very condensed, stream lined Acrosome forms from the Golgi Apparatus Modified secretory vesicle Digestive enzymes and sugars for energy Acrosome is positioned over the nucleus

Sperm Maturation :

Sperm Maturation In some species the space between the acrosome and nucleus is occupied by globular actin Used later to form an acrosomal process for fertilization Together the nucleus and acrosome make the Head of the sperm

Sperm Maturation :

Sperm Maturation Flagellum allows for propulsion Motor called the axoneme Microtubule coming from the centriole at base of nucleus The energy for the whipping motion comes from the mitochondria located in the midpiece

Sperm Maturation :

Sperm Maturation In mammals released sperm can move but cannot fertilize Final stages of maturation are called Capacitation This occurs in the female reproductive tract

Slide 442:

Pre- oviposition phenomena

Figure 10-16:

Figure 10-16 Anuran calling Gray tree frogs Male tungara frog – air is forced from lungs into vocal sacs

Slide 444:

Long distance migration e.g., sea turtles Feeding grounds of green turtles nesting on Costa Rican beaches and on Ascension Island Satellite tracks of turtles moving from Ascension Island back to feeding grounds off the coasts of Brazil

Slide 445:

Finding / attracting mates Nest exchange in northern gannets Male greater prairie chicken

Pre-ovulatory reproductive investment e.g., nest prep:

Pre-ovulatory reproductive investment e.g., nest prep Australian mallee fowl Coot Bald eagle Piping plover

Mating Systems :

Mating Systems Birds

Social Monogamy:

Social Monogamy Pair bond with ONE member of the opposite sex 92% of all bird species Occurs if Males are needed for raising the young Ring-billed gull

Social Monogamy:

Social Monogamy Can occur for a single breeding instance Can be for single breeding season Can be for many breeding seasons Osprey

Extra-Pair Copulations:

Extra-Pair Copulations Reported in All species Even monogamous Results in Extra-pair fertilizations, extra-pair young In some populations it occurs in 50% of a population

Extra-Pair Copulations:

Extra-Pair Copulations Benefits to males Increased fitness of offspring Increases in acquisition of future mates Safeguard against mate infertility Cost to males Sperm depletion and ejaculatory energy costs Risk of cuckoldry Reduction in parental care Increased likelihood of ‘divorce’

Extra-Pair Copulations:

Extra-Pair Copulations Benefits to females Fertility insurance Genetically diverse young Improved genetic quality of offspring Access to resources Cost to females Male retaliation Risk of injury to self or young Harassment from extra-pair males


Polygyny Males mate with many females Females mate with only one male Parental care from female Males control a defined territory ~2% of all birds Red-winged blackbird

Polygyny :

Polygyny Why would females tolerate this when other males are free? Territorial quality is correlated to reproductive success Ratio threshold where bigamy will be tolerated if it means success Reproductive success

Successful Polygyny:

Successful Polygyny What makes a successful male mate Age, experience and status Mating with a dominant male then maybe offspring will get the traits Sage grouse on lek

Successful Polygyny:

Successful Polygyny Sexual dimorphism Selection based on displays, plumage or colors If male has energy to make better plumage then he is healthier, feeds better Sage grouse on lek

Successful Polygyny:

Successful Polygyny Truth in advertising Costs to defend larger territories Costs to make better plumage Costs to mate with many females Sage grouse on lek

Successful Polygyny:

Successful Polygyny Runaway Selection Males picked for traits that don’t equate to better survival Peacocks Tail very costly Flag to predators Less agile Overall the species is less well adapted


Polyandry One female with several males When parental care from males Less than 1% of all birds Sex-role reversal Females larger and more brightly colored Northern jacana


Polyandry Evolved in species with defined clutch sizes Reproductive advantage means mating with more males Laying more clutches Spotted sandpiper


Promiscuity Indiscriminant sexual relationships Males never see their young Maternal care predominates 6% of all birds Salt marsh sparrow


Promiscuity Salt Marsh sparrow deemed most promiscuous bird Each clutch can have offspring from different fathers Because nests are vulnerable Different fathers means better chance at success Salt marsh sparrow

External Fertilization:

External Fertilization Many species release sperm and egg into a hostile environment Same environment has gametes from many other species as well Attraction over distance Most species mature ovums secrete chemicals that allow sperm to find them Sperm move (chemotax) up a concentration gradient Species Recognition Chemotactic molecules are VERY species specific Fusion proteins on sperm and egg

Internal Fertilization:

Internal Fertilization Three strategies for Development Oviparity = fertilized eggs placed outside mothers body to complete development in an amniotic egg Ovoviviparity = fertilized eggs are kept in mother (often in an amniotic egg) to complete gestation; nourishment form egg yolk, not mom Viviparity = young develop in mother and get nutrition from her blood


Fishes Most are external fertilizers Thousand of eggs are laid and fertilized Cartilaginous fish are internal fertilizers Males have claspers as intromissive organs for sperm deposition


Amphibians Most are external Some sexual selection Calling Males spreads sperm over eggs as they are laid


Reptiles Most are oviparous Some viviparous Most are internal fertilizers Males use penis Lay hard or leathery eggs Anolis


Birds All birds are oviparous No intromissive organs Use a cloacal kiss

Slide 469:

Post-oviposition phenonmena Parental care


Amphibians Development is mostly in water Embryonic, larval and adult stages Some exceptions

Slide 471:

Male tungara frog whips jelly into foam – tads digest foam Female Surinam toad Eggs on back Female rocket frog Hatching tads on back Carried to water Northern glass frog Eggs on underside of leaf – tads drip into water Female Spix’s horned frog Tads develop / metamorphose on back Male Darwin frog Developing tads in vocal sac

Obligate Brood Parasite:

Obligate Brood Parasite Females lay eggs in the nests of other birds Often of similar size and coloring Brood Mimetic Evolved independently 7 times Over 90 species Brown-Headed Cowbird

Obligate Brood Parasite:

Obligate Brood Parasite Short gestations Rapid growth post hatching Advantage of parasite over the host nestlings Often larger than the host Some kill hosts nestlings Brown-Headed Cowbird

Obligate Brood Parasite:

Obligate Brood Parasite Why would hosts tolerate Mafia theory Parasites monitor the nests they have used If parasite brood not taken care of they will denest the host Great spotted cuckoo

Host Strategies against Parasitism:

Host Strategies against Parasitism Nest in unfavorable places Monitor nests and defend Kill parasites Riskier if parasite is mimetic Abandon nest and start over Great spotted cuckoo

Slide 476:

Post-oviposition phenonmena Complex life cycles

Larval Stages:

Larval Stages Many amphibians have evolved away from tadpole Some advantages Completely different body plan and ecology

Larval Stages:

Larval Stages Aquatic larva have ovoid bodies and large tail fins Most are filter feeding herbivores Adults are carnivore As larva grow it is harder to feed enough to maintain size

Control of Metamorphosis:

Control of Metamorphosis Things to increase rates Temperature increases Food levels decrease Tadpole density increasing Water evaporation rates Increased predators


Metamorphosis Three stages Premetamorphosis = larva grow with no change in structure Prometamorphosis = hind legs appear; grow rate slows down Metamorphic climax = forelimbs complete and tail regresses

Thyroid Control:

Thyroid Control Stages of metamorphosis are correlated to levels of thyroid hormones Increased expression of Thyroid and Retinoic acid receptors Work as a dimer

Thyroid Control:

Thyroid Control Transition to premetamorphosis parallels increases in T 4 T 3 peaks at end of Prometamorphasis T 4 peaks at height of climax

Figure 17-34:

Figure 17-34 Precocial vs altricial young Snowy plover Tree swallow

Figure 21-1:

Figure 21-1 Precocial vs altricial young in mammals n.b., costs of lactation

Metabolism and thermal biology :

Metabolism and thermal biology Pg96-103; 191-195; 281-289; chapter 14 and 22

Temperature and Performance:

Temperature and Performance All biological processes have optimal temperatures All processes are driven by proteins and enzymes Have optimal temperatures for form and function Willmer et al. 2000. Environmental Physiology of Animals

Figure 13-16:

Figure 13-16 thermal sensitivity of performance in garter snakes

Temperature and Performance:

Temperature and Performance Each species has an optimal temperature for each process Withers 1992 Comparative Animal Physiology

Temperature and Performance:

Temperature and Performance Biologists calculate Q10 ratios to monitor temp effect Rate at temp X+10/ rate at temp X =1 then rate is stable <1 then rate is decreasing >1 rate is increasing

Q10 ratios:

Q10 ratios max swim speed in goldfish LDH activity in lungfish spontaneous activity in goldfish

Standard Metabolic Rate:

Standard Metabolic Rate Rate of oxygen consumption needed to sustain life Oxygen needed to maintain ATP levels to run all these basal processes Digestion of food; glycolysis, electron transport and oxidative phosphorylation.

ATP Formation:

ATP Formation Production of ATP from digested food macromolecules Cytosol Breakdown of food macromolecule subunits Oxygen NOT required Sugars primarily But amino acids and Fatty acids too Mitochondria Uses energy trapped in carrier molecules to generate ATP Acetyl CoA, NADH, FADH2 Needs Oxygen

Stage Two of Glucose Catabolism: Glycolysis:

Stage Two of Glucose Catabolism: Glycolysis Occurs in the cytosol Breakdown of subunits into molecules of pyruvate ( pyruvic acid) Glycolysis (breakdown of glucose) creates two types of high energy molecules ATP NADH

Stage Three of Glucose Catabolism: Oxidation:

Stage Three of Glucose Catabolism: Oxidation Occurs in Mitochondria Pyruvate is converted into Acetyl CoA and CO 2 Energy stored in Acetyl CoA is captured as NADH & FADH 2 in the citric acid cycle Electrons from these are passed through ETC to generate ATP

Stage Three of Glucose Catabolism: Oxidation:

Stage Three of Glucose Catabolism: Oxidation Stage Three also called oxidative phosphorylation Consumes oxygen to generate ATP by phosphorylation ADP ATP is moved out of mitochondria to the cytosol for use

Standard Metabolic Rate:

Standard Metabolic Rate Rate of oxygen consumption needed to sustain life Oxygen needed to maintain ATP levels to run all these basal processes Ventilation, blood pumping, ion flux across membrane Does not include growth, locomotion, etc SMR is effected by temperature


SMR If an organism’s Q10 rate is 2 and it uses X energy at 10 o C 2X at 20 o C 4X at 30 o C As the temperature increases then energy use increases and so food consumption must increase

Slide 499:

Patterns of temperature control


Thermoregulation All processes are temperature dependant Higher body temps require more food to keep SMR Makes sense for an organism to try and keep body temperature stable

Old Classification of Vertebrates:

Old Classification of Vertebrates Poikilotherms – variable body temperatures As ambient rises so does body temp Homeotherms – Stable body temperatures No fluctuations as body temps rise and fall

New classifications :

New classifications Ectotherms get energy from their surroundings Basking in sunlight Endotherms depend on internal metabolic processes to generate body heat Eckert Animal Physiology 1997

New classifications :

New classifications Reflects the SOURCE of energy used for thermoregulation Not how variable the body temp is

New classifications :

New classifications Not equal to the old classifications Benthic fish Ectoderms Homeotherms because environment doesn’t change Eckert Animal Physiology 1997

Thermoregulation by modifying behavior:

FIGURE 5-13 Relationship between body temperature and air temperature for thermoconforming lizards (Draco, Anolis, in shaded forest habitat) and thermoregulating lizards (Amblyrhynchus, Anolis, in open habitats); also shown is the relationship for an inanimate object (water-filled metal can). Withers 1992 Comparative Animal Physiology Thermoregulation by modifying behavior

Figure 8-18:

Figure 8-18

New classifications :

New classifications Reptiles normally ectotherms Female snakes will heat eggs by increasing body metabolism Eckert Animal Physiology 1997 Willmer et al. 2000. Environmental Physiology of Animals

New classifications :

New classifications Heterothermy occurs when endotherms show wide swings Nighttime torpor Body temp drops to 1 o above ambient Extreme cold climates Not enough food to maintain temp all the time Eckert Animal Physiology 1997

New classifications :

New classifications Heterothermy occurs when endotherms show wide swings “Nighttime” torpor Body temp drops to 1 o above ambient Extreme cold climates Arctic Grounds squirrels to -2.9 o C Not enough food to maintain temp all the time Eckert Animal Physiology 1997

New classifications :

New classifications Migratory torpor Birds flying long distances Drop temps to make sure energy stores last the flight Eckert Animal Physiology 1997

New classifications :

New classifications Seasonal Torpor True hibernation Comatose state for days/weeks at a time Mostly in smaller endotherms NOT Bears Eckert Animal Physiology 1997


Torpor Larger mammals do not experience true torpor Can lower body temp some True torpor saves a lot of energy Substantial cost to reheat Too high a cost for large animals

Endotherms v. Ectotherms:

Endotherms v. Ectotherms

Endotherms v. Ectotherms:

Endotherms v. Ectotherms Endotherms have higher baseline metabolisms as compared to similarly sized ectotherms 5-10 times higher on average Endotherms carry increased insulation as compared to ectotherms Hair, fur, feathers, fat Endotherms control metabolism neurally When the outside temps go up the metabolic rate gets slowed down and vice versa


Ectotherms Body temperature is proportional to ambient temperature Metabolic rate proportional to body temp No neural control Hill and Wyse 1989. Animal Physiology


Endotherms Body temp not proportional to the ambient temperature Metabolic rate not always proportional As air temp increases, body temp stays stable because metabolism goes down


Endotherms Neural control of metabolism When body temp shift away from set point Hypothalamic responses Does NOT happen in Ectotherms Eckert Animal Physiology 1997


Insulation Insulation affects how endotherms maintain Colder climates more insulation means less metabolic investment Warmer climates insulation can negatively impact

Slide 520:

Eckert Animal Physiology 1997

Slide 521:

Behavioral thermoregulation

Exothermal behaviors:

Exothermal behaviors Adjusting location to maintain their body temperature Will also affect the metabolic rate

Slide 523:

Basking and orientation to the sun in Galapagos marine iguanas

Slide 524:

Eckert Animal Physiology 1997

Behavioral Thermoregulation and Habitat Use:

Behavioral Thermoregulation and Habitat Use Climate dictates where an ectotherm can live or spend a majority of time

Ectotherms regulate habitat and behavior, too:

Based on Folk, G.E. (1974) Textbook of Environmental Physiology (2nd edn), Lea and Febiger Ectotherms regulate habitat and behavior, too

Antelope Ground Squirrel:

Antelope Ground Squirrel Burrow dwelling Stints out of burrow with high activity High body temperature Release heat in the burrow Willmer et al. 2000. Environmental Physiology of Animals

Cape Ground Squirrel:

Cape Ground Squirrel Uses tail as a parasol Shields from the sun Lowers operative temperature considerably Withers 1992 Comparative Animal Physiology

Insulation and Dermal Exchange:

Insulation and Dermal Exchange Increased volume of insulation can prevent loss of heat through conductance Fluffing/shedding of fur Increased blubber

Insulation and Surface Color :

Insulation and Surface Color Both color and posture of feathers impact radiation absorbed

Regulation of Body Temperature:

Regulation of Body Temperature Heat production comes from metabolism of food High body temps cause dermal capillaries to fill Transfer of heat energy via several mechanisms

Regulation of Body Temperature:

Regulation of Body Temperature Evaporation of sweat Heat energy used to turn water in to vapor Radiation Transfer of heat energy to the cooler objects in environment Major force in loss of body heat

Regulation of Body Temperature:

Regulation of Body Temperature Conduction Transfer of heat energy to object in contact with the body (clothing, jewelery) Convection Transfer of heat energy away from body by moving air/fluid

Slide 534:

(Kluger 1979) Eckert Animal Physiology 1997

Circulatory Control of Cutaneous Heat Exchange:

Circulatory Control of Cutaneous Heat Exchange ArterioVenous Bypasses close to body core When open Keeps warmer blood deeper Prevents heat loss Countercurrent exchange phenomena

Countercurrent Heat Exchangers:

Countercurrent Heat Exchangers Very important in cold environments Manages heat loss at extremities Arteries surrounded by venous channels Blood flows in opposite directions Hill and Wyse 1989. Animal Physiology

Countercurrent heat exchangers:

Countercurrent heat exchangers Venous blood from extremities is very cool Arterial blood is very warm Heat from arteries is returned to veins Arteries are cooler when they get to endpoints Less body heat is lost to external environments

Regional Heterothermy in Endotherms:

Regional Heterothermy in Endotherms Allows for an endotherm to tolerate colder skin temperatures Conservation of core body temperatures Limits conduction, convection and radiation loss

Thermoregulation in Fish:

Thermoregulation in Fish Many fish are ectothermic Lots of heat loss through gills Cool water and core blood already in counter current mode Gas exchange Heat exchange

Heterothermic Fish:

Heterothermic Fish Some fish have higher metabolic rates Fast swimmers Lots of muscles Rete Mirable in muscles vessels set up in counter current systems Warm blood from muscles used to keep core warm Minimizes loss at skin

Slide 541:

Blue fin tuna countercurrent A-V heat exchange rete (Carey and Teal 1966). Eckert Animal Physiology 1997

Protective Countercurrent Exchangers:

Protective Countercurrent Exchangers Brain cooling in animals living in tropical locals Panting cools blood in pharynx Passes through heat exchanger to cool arterial blood Before it goes to brain

Slide 543:

Fig. 13.34 (a) Blood flow rate and water loss rate in an exercising panting dog, also showing increments of rectal and brain temperature (T rectal and T brain ) but with T brain much lower due to the cooling effect of panting. (From Baker 1982.) Willmer et al. 2000. Environmental Physiology of Animals Evaporative heat exchange

Gular Fluttering:

Gular Fluttering Some birds experience gular fluttering Flapping of gular skin Like a pant To cool the blood by evaporation Protects the brain

Water Retention :

Water Retention Dromedary Camels Water storages helps maintain temp Dehydration times cause increase in water retention Dehydration results in wide temp swings

Huddling – Social Cooperation:

Huddling – Social Cooperation Emperor penguins 2500 in group Huddle to keep warm Social status determines rotation rates to inside of huddle

Slide 547:

Producing heat

Futile metabolic cycles:

Futile metabolic cycles Burn ATP in never-ending cycles Portion of Glycolysis Ion transport and leakage Uncoupled fatty acid metabolism

Brown Adipose :

Brown Adipose Coming out of Torpor Brown adipose has lots of mitochondria Fat oxidation is uncoupled from energy production All energy is released as heat Non shivering thermogenesis

Uncoupling Proteins :

Uncoupling Proteins Fat is oxidized; Kreb’s cycle runs; ETC runs Protons run through UCP channels and NOT ATP synthase No energy made; only heat released

Body Mass Impact:

Body Mass Impact Non shivering thermogenesis used by smaller animals Use a significant amount of metabolism to maintain temp Larger animals rely on insulation Withers 1992 Comparative Animal Physiology

Heater Tissues in Fish:

Heater Tissues in Fish Futile calcium pump loops Calcium channels in SR are kept open Ca-ATPase in SR membrane uses ATP to pump back in Heat generated Billfish heater tissue pathway (Block 1994). Eckert Animal Physiology 1997

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