1. HomeostasisBasic feedback mechanisms and Thermoregulation

2. Homeostasis = The physiological state of the body in whichinternal physical and chemical conditions arekept within a range that is suitable for lifeprocesses Not steady state, but often described as a balancing act 3. Normal body temperature : 37 CHuman cells need 35 C 37.8 C in order to functionOrganisms survival depends on the bodies ability to maintain an internal environment The extracellular fluid, which consists of the interstitial fluid filling spaces between cells and tissues and the plasma or fluid portion of our blood 4. Sensor (tissue/organs thatdetect change)Integrator (processing / control center)The Effector (the system whichThereturns body toResponsemeasured condition) 5. Homeostasis Mechanisms Responsible for maintaining homeostasis in response to internal orexternal environmental changesUsed to evaluate the environment and conditions, and take correctiveactionsNervous systemExternal Internal influences influences Endocrine system 6. Negative Feedback Mechanisms- Primary mechanism- Stimulus resulting from a change in the external or internal environment triggers a response that compensates for the change- To bring internal conditions back into balance, negative feedback mechanisms use antagonistic effectors- Antagonistic = they act to produce the opposite effectof the change recorded by the sensor 7. Negative Feedback Stimulus (enviromental Systemschange) Sensor (ie: nerve ending in skin) Integrator(ie: the Brain) Effector The response of the(muscle orsystem cancels or gland)counteracts the effectof the originalenvironmental change Response (systemsoutput) 8. Integrator(ie: the Brain)The Set Point EnvironmentalConditions 9. Examples 10. Experiment Time In a clean glass jar place several ants, cover witha lid Submerge half the jar in ice/ice water Place hands around the upper portion of the jar After 5-15 minutes the ants will have movedclose to warm hands to attempt to maintainhomeostasis 11. Positive Feedback Feedback mechanism Increases the change in environmental conditions Usually do not result in homeostasis Ie: the release of adrenaline when an animal isattacked 12. Thermoregulation Based on negative feedback Absorb thermal energy if they are cooler thanenvironment Release thermal energy if they are warmer thanenvironment sweat 13. Conduction= flow of energy when they come in contact with acolder or warmer body