Homeostasis ib 2010 upload version


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Homeostasis ib 2010 upload version

  1. 1. Homeostasis (and some Endocrine System too) I’m outta Cat pictures!04/18/12 09:28 cottingham
  2. 2. Homeostasis and Excretion Homeostasis – maintaining the internal environment at a constant level or between narrow limits. Involves nervous and endocrine systems: – Receptors monitor level of “variable” – Brain regulates level of variable – Effectors bring about changes as directed by the brain04/18/12 09:28 cottingham
  3. 3. HomeostasisThe parameters controlled include: Blood pH and CO2 concentration Body Temperature (Thermoregulation) Blood glucose concentration Water Balance (Osmoregulation)04/18/12 09:28 cottingham
  4. 4. Negative Feedback Hasa stabilizing effect: change in “levels” always causes an opposite change: – Rise in levels = decrease in production = reduction in levels – Decrease in levels = increase = raise the levels04/18/12 09:28 cottingham
  5. 5. Thermoregulation Temperature regulation: thermoreceptor – Endotherm – mammals and birds – Ectotherm – reptiles… Source of heat: Aerobic Cellular Respiration Main methods of heat loss: Conduction, Convection, and Radiation. Require coordination between nervous and endocrine 04/18/12 09:28 cottingham
  6. 6. Thermoregulation Thermoreceptors send impulses to hypothalamus whichstimulates the Pituitary Gland to release TSH into the Thyroid Gland to release ThyroxinThyroxin causes the body to increase metabolic rate releasing more heat. (less thyroxin in hot weather) 04/18/12 09:28 cottingham
  7. 7. Shivering04/18/12 09:28 cottingham
  8. 8. Sweating04/18/12 09:28 cottingham
  9. 9. Blood Glucose Level There is a direct relationship between the digestive system (eating), exercise, and glucose level.04/18/12 09:28 cottingham
  10. 10. Type I vs. II Diabetes Type I Type II Onset usually during  Can occur at any age childhood  Target cells show Beta pancreatic cells insensitivity to insulin produce insufficient  Does not require insulin. synthetic insulin Must take synthetic  Correlated to obesity insulin  Can be controlled with Cannot be controlled low carb diets by diet04/18/12 09:28 cottingham
  11. 11. Osmoregulation Control of Water Balance Process that keeps the osmotic pressure of the blood and tissue fluid constant Depends on: – the amount of H2O present. – the “salt” content of the blood.04/18/12 09:28 cottingham
  12. 12. Hormones and Osmoregulation Aldosterone  Regulates Na reabsorption and K excretion  Presence of hormone stimulates excretion of K and reabsorption of Na. – Sodium reabsorbed – Water follows to maintain proper blood volume. – Helps to maintain proper blood pressure.  High Salt Level Raises Blood pressure – Helps to control blood pH levels – secretion of H+ into tubules. – When K levels in blood are too high: Aldosterone secreted – K from blood to tubule04/18/12 09:28 cottingham
  13. 13. Hormones and OsmoregulationADH (Antidiuretic Hormone) Released by pituitary gland in response to signal from the hypothalamus(brain).  Responsible for final reabsorption of water  In collecting duct. – Lower levels of water: release of ADH into blood. – ADH causes the cell membranes in collecting duct to become permeable to water. – Process reverses when water level is restored.04/18/12 09:28 cottingham