1. Homeostasis and Control Systems

2. Homeostasis Body works best at a certain set point However the environment is constantly changing and your body must respond Body Temp = 37 pH = 7.35 Blood glucose = 0.1% Homeostasis is the bodies ability to maintain balance…when it gets out of balance that is when things go wrong

3. 3 Functional Components All control systems have functional components to make sure everything stays in balance 1. A monitor 2. Coordinating centre 3. Regulator Homeostasis is often referred to as Dynamic equilibrium - stays stable even with fluctuations *body’s limits are fluctuating*

4. Homeostasis and Feedback When the body gets out of balance there needs to be a system that helps bring it back Negative feedback - restores body’s settings back to set point Works like a thermostat Positive feedback - increases change, pushes it past set point Where might this be necessary?

5. Thermoregulation Temperature range control Ectotherms: body’s temp depends on the environment to help maintain Endotherm: body’s temp is regulated regardless of the external environment Hypothalmus: regulates body’s temperature, natural thermostat Everyone’s is different

6. Body’s response to temp stress Heat Exercise or high environmental temperatures Nerve impulse to hypothalmus, signals sweat glands to start secreting sweat Evaporation cools body down Nerve also sends signal to blood vessels causing them to dilate causing more blood flow to the skin

7. Cold Initiated the same way as with heat Signal is sent to hypothalmus Hypothalmus signals muscles to contract/constrict which will limit blood flow Hair stands on end, traps warm air Shivering: muscle contractions 10 - 20 times per minute Prolonged exposure to cold temps will increase metabolism - heat is generated Table 1 pg 341 *copy in notes

8. HWK Read pgs 335 - 341 # 1 -7 pg 341