Circulatory system


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Material exchange of body: Circulatory system


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Materials Exchange in the Body : 

18 1 Materials Exchange in the Body Dr Meera Narasimha ICFAI UNIVERSITY, HYDERABAD

Outline : 

18 2 Outline Exchange Materials: Basic Principles Homeostasis Limitations to Cell Size Circulation The Nature of the Blood The Immune System The Heart Arteries and Veins Capillaries


18 3 MATERIAL EXCHANGE IN THE BODY Many living things are complex with many parts that work together in coordination. All the systems are connected and work together. Materials need to be exchanged, and these exchanges must be regulated.


18 4 HOMEOSTASIS Homeostasis is the maintenance of a constant internal environment as a result of monitoring and modifying the functioning of various systems. For example: A person run, his heart beat increases to supply energy, breathing becomes faster to supply oxygen, sweating cools the body, etc.

Running up a hill: Maintenance of Homeostasis : 

18 5 Running up a hill: Maintenance of Homeostasis Leg & arm muscles in coordination Burning of glucose CO2 and Lactic acid Lowers the pH of Blood Heart beat fast to provide O2 and Nutrients to muscles. Breath faster to exchange O2 with CO2. Blood vessels (muscle) dilate to allow more blood to flow to them. Run generate excess heat. Blood flows to skin to remove heat, sweat glands begin to secrete thus cooling the skin.

Maintenance of Homeostasis: Involvement of Various automatic internal mechanisms. : 

18 6 Maintenance of Homeostasis: Involvement of Various automatic internal mechanisms. All of these automatic internal adjustments to help the body maintain a constant level of O2, CO2, glucose, pH, constant temperature. Various mechanisms help organisms maintain homeostasis.


18 7 LIMITATIONS TO CELL SIZE Cells are highly organized units and require food and oxygen to perform their functions. The waste products produced must also be removed through the cell surface. As the cell grows, its volume increases and the metabolic activity to maintain it rises.


18 8 LIMITATIONS TO CELL SIZE As the cell size increases, the exchange with the environment also increases. Cell size cannot increase indefinitely, thus there must be factors which will limit growth. This includes: The strength of the cell membrane. The cell surface area. The surface area-to-volume ratio.


18 9 LIMITATIONS TO CELL SIZE The strength of the cell membrane. As the cell increases in size, it reaches a point where the membrane cannot withstand the internal forces anymore. The cell surface area. Cell membranes let materials in and out selectively. As the cell increases, the cell surface determines how much can get in or out.

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18 11 LIMITATIONS TO CELL SIZE Cell surface area-to-volume ratio. Metabolic needs are determined by volume, but how much material can be exchanged in and out is determined by the surface area. As the cell increases in size its volume increases faster than its surface area. Therefore, the surface area-to-volume ratio decreases.


18 12 LIMITATIONS TO CELL SIZE The ability to transport materials in cells is determined by its surface area, whereas its metabolic demands are determined by its volume. The larger the cell, the more difficult to satisfy its needs. Thus to solve this problem cells have highly folded cell membranes to increase their surface area.

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18 14 CIRCULATION Large organisms have trillions of cells. To distribute material, a distribution system (circulation) is required. The circulation system is made of blood, heart, arteries, veins, and capillaries. Blood consists of a fluid (plasma), cells (red blood cells, white blood cells), and many other dissolved materials.

Circulatory system : 

18 15 Circulatory system Blood: Transport of materials and Heat Heart: Pump Blood Arteries: Distribute blood from heart to Organs Capillaries: Exchange between blood and tissue through walls of capillaries Veins: Return blood to heart from tissues


18 16 CIRCULATION Heat is also transported by blood. Heat is generated by metabolic activities and must be lost from the body. In humans, one method used to lose heat is by evaporation of sweat to get rid of the excess heat. Plasma also carries nutrient molecules from the gut to other locations where they are modified, metabolized, or incorporated into cells.


18 17 CIRCULATION Blood is used to transport: oxygen carbon dioxide nutrients waste products disease fighting antibodies chemical messengers (hormones) blood clotting substances

Nature of Blood : 

18 18 Nature of Blood Anemia: Person has reduced O2 carrying capacity. Transport of Oxygen: Binds Hemoglobin and transported to different parts of the body. Carbon-di-oxide Transport: Carried by blood in 3 forms 7% in dissolved in Plasma 23% bind to hemoglobin 70% in the form of bicarbonate ion form

Nature of Blood : 

18 19 Nature of Blood In RBC: In the presence of Carbonic anhydrase CO2 + H2O H2CO3 H+ + HCO3- In Lungs: Dissolved CO2 is lost from the plasma and from hemoglobin. Bicarbonate ions can be converted back as CO2.

Nature of Blood : 

18 20 Nature of Blood Plasma carries nutrient molecules from the gut to other locations where they are modified , metabolized or incorporated into cell structures. Amino acids, simple sugars dissolved and carried as dissolved molecules in the blood. Lipids are combined with proteins and carried as lipoprotein molecules. They generally carried to blood stream by lymphatic system. Liver: Manufacture and modify molecules so, constant supply of raw materials and distribute their products to cells.


18 21 THE IMMUNE SYSTEM White blood cells recognize foreign materials and, among other things, make antibodies to fight diseases. White blood cells like neutrophils, eosinophils, basophils, and monocytes are capable of destroying antigens by phagocytosis.

Formed Elements of Blood : 

18 22 Formed Elements of Blood


18 23 THE IMMUNE SYSTEM Immune system: Protects the body from many diseases. WBCs are carried in the blood are involved in defending against harmful agents. Immunity will be provided in several ways: Antibody mediated immunity by B cells. Neutrophils, eosinophils, basophils and monocytes able to engulf foreign materials. Cell mediated immunity by T cells. Platelets: Blood clotting.


18 24 THE IMMUNE SYSTEM The two major groups of lymphocytes are B-cells and T-cells. B-cells produce antibodies in response to antigens. T-cells are involved in T-cell mediated immune response. In addition to being effector cells, T-cells also help B-cells to produce antibodies.


18 25 THE HEART The heart is the organ that acts as a pump to circulate blood throughout the body. Heart is a muscular pump that provides the pressure necessary to propel the blood throughout the body. Heart is always in continuous cycle of contraction and relaxation. The heart in humans, other mammals, and birds consists of 4 chambers and 4 sets of valves. Four chambers and four sets of valves work together , so blood flows in one direction only.


18 26 THE HEART Two of the chambers, the left and right atria, are relatively thin-walled structures that collect blood from veins and empty into larger and more muscular ventricles. Flow of the blood from the atria to the ventricles is caused by lowered pressure produced within the ventricles as they relax.

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18 29 THE HEART The ventricles are chambers that have powerful muscular walls whose contraction forces blood to flow through the arteries to all parts of the body. Atrioventricular valves: Valves between the atria and ventricles, are one way valves that allow blood flow from atria to the ventricles (one way flow) Semilunar valves: Valves in aorta and pulmonary artery; prevent the flow of blood from the aorta to the ventricles .

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18 30 Heart valves are valves in the heart that maintain the unidirectional flow of blood by opening and closing depending on the difference in pressure on each side. There are four valves of the heart (not counting the valve of the coronary sinus and valve of the inferior vena cava): The two atrioventricular (AV) valves ensure blood flows from the atria to the ventricles, and not the other way. The two semilunar (SL) valves are present in the arteries leaving the heart, and they prevent blood flowing back from the arteries into the ventricles


18 31 THE HEART Aorta: Large artery that carries blood from left ventricle to the body. Pulmonary artery: Carries blood from the right ventricle to the lungs. If valves are damaged or function improperly, functional efficiency of heart diminishes. Improper functioning of heart cause abnormal sounds known as heart murmurs. Coronary arteries: Branches of Aorta, supply blood to muscles of heart.


18 32 THE HEART Pulmonary circulation: Right side of the heart receives blood from general body and pumps it through the pulmonary arteries to the lungs where exchange of gases takes place and pure blood returns from lungs to left atrium. Systemic circulation: Left side of the heart delivers the pure blood through aorta to all parts of the body and returns impure blood to the right atrium by veins.

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18 34 ARTERIES AND VEINS Arteries carry blood from the heart to all parts of the body. The contraction of the walls of the ventricles create the pressure required to push the blood. The systolic pressure is a typical pressure in large artery when heart contracts is about 120 mm of Hg. The diastolic pressure is When heart relaxes the pressure is about 80 millimeters of mercury.

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18 36 ARTERIES The walls of the arteries are relatively thick, muscular, and yet elastic. Arteries has the ability to expand and return to normal state during blood pumping. Artery has the ability to absorb some pressure and reduce peak pressure. Artery hardened and less resilient, its peak blood pressure rises and chance for rupture.


18 37 ARTERIES Elastic nature of artery give a little push to blood that is flowing through them. Blood ? Large aorta ?Small arteries? Smaller blood vessels? Millions of tiny capillaries. Arterioles: Some of the small arteries may contract or relax to regulate the flow of the blood to specific parts of the body.


18 38 ARTERIES Major parts of the body receive differ in amounts of blood, depending on need are digestive system, muscles and skin. During exercise, increase blood flow to muscles. Exercise increase flow of blood to skin. Athletes do not eat a full meal before exercising because, amount of blood to digestive system reduces and additional amount of blood needed to muscles and lungs for vigorous exercise.


18 39 VEINS Blood is distributed from the large aorta through smaller and smaller blood vessels to millions of small tiny capillaries. Veins collect blood from the capillaries and return it to the heart. The walls of veins are not as thick as those of arteries. Pressure in veins is low, sometimes in large veins a bp of 0mm of Hg for brief periods.

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Veins : 

18 41 Veins Veins have valves prevent blood from flowing backward away from heart. Varicose veins: Have faulty valves do not allow efficient return of blood to heart. Blood pools and become swollen, bluish networks.


18 42 VEINS Because the pressure in veins is low, muscular movements of the body are important in helping blood to return to the heart. When the muscles of the body contract, they compress the veins nearby.

Capillaries : 

18 43 Capillaries Arteries distribute blood Arterioles regulate blood flow Capillaries assist exchange of materials between blood and cells. Capillaries are tiny thin-walled tubes that receive blood from arterioles. Numerous and in Human 1000 square meters of surface area represented by capillary surface.

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18 45 CAPILLARIES Each capillary has a single layer of cells and presents only a thin barrier to the diffusion of materials between the blood and cells. Liquid flow through tiny spaces between the individual cells of most capillaries flow of blood is relatively slow, allows time for diffusion of O2, Glucose, Water from blood to surrounding cells and for the movement of materials such as CO2, Lactic acid, ammonia from cells into blood.

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Lymphatic Capillary : 

18 47 Lymphatic Capillary


18 48 CAPILLARIES In addition to molecular exchange, large amounts of water and dissolved materials leak through the small holes in capillaries. The leaked out fluid is called lymph. The lymph must be returned to the blood or a swelling will occur. Lymph is returned by circulation by the lymphatic system, into the veins near the heart.

The Lymphatic System : 

18 49 The Lymphatic System


18 50 CAPILLARIES Lymph filtered through lymph nodes before released into circulatory system. Lymph nodes contain large number of WBC that remove microorganisms and foreign particles. Spleen, tonsils and adenoids are large masses of lymph node tissue. Thymus is large and active in children produce T cells.

Thymus : 

18 51 Thymus


18 52 CAPILLARIES Flow across the Capillary wall is subject to change in pressure inside capillaries and tissues and Permeability of capillary wall. Edema: Swelling in tissue due more fluid enters into tissue. It is due to pressure inside capillary increase or permeability of capillary cell membrane increase results in more fluid leak from capillaries into tissues.

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