HOMEOSTASIS

The term" HOMEOSTASIS” Refers to a state of constancy in a system. In its normal, or resting state, a system often is said to be in homeostasis. Example: During exercise, sweating increases to maintain a constant internal temperature.

History of Homeostasis :

History of Homeostasis Claude Bernard (1813 -1 8 78) French physiologist Developed the concept of the internal milieu. Recognized that many animals regulate their internal environment even if the external environment changes. Walter Cannon (1871 - 945) Coined the term “Homeostasis” in 1926. Realized the importance of the autonomic nervous system in maintaining a constant internal environment.

Homeostasis :

Homeostasis Organism’s Internal Regulation Examples of physiological conditions requiring homeostasis: Temperature Concentration of Waste Products Gas Exchange pH Energy Requirements Water/Ion balance Volume/Pressure

Necessary Components of a Homeostatic System :

Necessary Components of a Homeostatic System Receptor Control Center Effecter RECEPTOR CONTROL CENTRE EFFECTER

Homeostatic Mechanism :

Homeostatic Mechanism Feedback Regulation

In Organisms :

In Organisms ANTARCTIC CONDITIONS IN DESERT

Behavioral Responses to Temperature (Endothermic) :

Behavioral Responses to Temperature (Endothermic) Change location Change body position Change color or weight of fur or clothing

Endothermic Responses to Cold :

Endothermic Responses to Cold Shivering Blood vessels constrict Release of thyroid hormone Activation of brown fat

Endothermic Responses to Heat :

Endothermic Responses to Heat Perspiration In species that do not perspire, animals may pant or lick their fur Blood vessels dilate PANTING

Glucose Homeostasis Chart :

Glucose Homeostasis Chart

Glucose Homeostasis :

?-cells release glucagon stimulate glycogen breakdown and gluconeogenesis ?-cells release insulin stimulate glucose uptake by peripheral tissues Glucose Homeostasis Lower Blood Glucose Higher Blood Glucose Food Between meals

Regulation of sodium and water balance :

Regulation of sodium and water balance Three major hormones are involved in regulating sodium and water balance in the body at the level of the kidney. 1)ADH(antidiuretic hormone) from the posterior pituitary acts on the kidney to promote water reabsorption, thus preventing its loss in the urine. 2)Aldosterone from the adrenal gland acts on the kidney to promote sodium reabsorption, thus preventing its loss in the urine. 3)ANH(atrial natriuretic hormone) from the atrium of the heart acts on the kidney to promote sodium excretion so that it is excreted in the urine.

Regulation of sodium and water balance :

Regulation of sodium and water balance

Disruption of Homeostasis :

Disruption of Homeostasis Injury Punctured Lung Illness Flu Disease Diabetes Death

DISEASE :HOMEOSTASIS and IMBALANCE :

Body processes remains within physiological limits……….body cells function well……….homeostasis is maintained………body is healthy. But when body processes ( 1 or >1) loose their ability to contribute to homeostasis. The outcomes would result in; - (if moderate)……..diseases results - (if severe)………….death results 1) LOCAL DISEASES - disease affecting limited part/ region of the body. 2) SYSTEMIC DISEASE- disease affecting entire body. 3) SYMPTOMS - Subjective changes (complains) in the body function that a patient complains about, and is not apparent to an observer. (e.g. pain complaint by patient) SIGNS - Objective changes that a clinician can observe and measure. - SIGNS can be ; (ANATOMICAL changes) – Swelling, rash (PHYSIOLOGICAL changes) – Raised blood pressure and raised body temperature DISEASE :HOMEOSTASIS and IMBALANCE

Type 1 Diabetes Mellitus :

Type 1 Diabetes Mellitus High blood glucose Detected by ?-cells ?-cells release insulin Peripheral cells respond to insulin by taking up glucose Lower blood glucose Normal Glucose Metabolism Type 1 Diabetes High blood glucose Detected by ?-cells ?-cells release insulin Peripheral cells respond to insulin by taking up glucose Lower blood glucose ?-cells destroyed by autoimmune reaction These steps do not happen because the ?- cells have been destroyed Blood glucose remains high

Type 2 Diabetes Mellitus :

Type 2 Diabetes Mellitus Time Peripheral Tissue Insulin Resistance v. Time Relative Insulin Resistance Time ?-cell Insulin Production ?-cell Insulin Production v. Time Disease Progression Age Birth Normal Glucose Homeostasis Pre-Diabetic Diabetic

Glucose Homeostasis Research Timeline :

Glucose Homeostasis Research Timeline 1552 BC: Ebers Papyrus in ancient Egypt. First known written description of diabetes. 1st Century AD: Arateus — “Melting down of flesh and limbs into urine.” 1776: Matthew Dobson conducts experiments showing sugar in blood and urine of diabetics. Mid 1800s: Claude Bernard studies the function of the pancreas and liver, and their roles in homeostasis. 1869: Paul Langerhans identifies cells of unknown function in the pancreas. These cells later are named “Islets of Langerhans.” 1889: Pancreatectomized dog develops fatal diabetes. 1921: Insulin “discovered” — effectively treated pancreatectomized dog. 1922: First human treated with insulin. Eli Lilly begins mass production. 1923: Banting and Macleod win Nobel Prize for work with insulin. 1983: Biosynthetic insulin produced. 2001: Human genome sequence completed.

Current/Future Research in Diabetes :

Current/Future Research in Diabetes Current Clinical Trials: physiological traits of patients/response to therapeutics Genetic Approaches: candidate genes; family-based studies; genome-wide scans Animal Models: developing gene-knockout models; large-scale mutagenesis studies to produce diabetic phenotypes Microarray Analysis: analysis of gene expression in tissues Future Continued utilization of human genome sequence data Sequencing multiple ethnicities ?-cell transplantation

Conclusion :

Conclusion “Homeostasis” is the ability of the body to maintain a constant internal environment by making small internal adjustments to compensate for large external disturbances. Injuries, illness, disease and death can disrupt homeostasis. Diabetes causes disruption of glucose homeostasis. It is only one example of the potentially severe problems caused by disrupting homeostasis. Science is actively pursuing a broader, more detailed understanding of homeostatic mechanisms and the consequences of their disruptions.