Unit 4 Homeostasis Homeostasis same balance Homeostasis the
Unit 4 - Homeostasis!
Homeostasis… same balance • Homeostasis: the ability of an organism to maintain a relatively stable internal environment • Fluctuations occur around the steady state set point (the “normal” range) External environment Internal environment large fluctuations Homeostatic mechanisms small fluctuations
Homeostasis Norms Homeostatic component Normal range Unit Body temperature 36. 2 -37. 2 o. C Blood p. H Resting heart rate 7. 35 -7. 45 50 -100 p. H units bpm Blood pressure 90/60 to 120/80 mm. Hg Resting breathing rate 16 -20 breaths/min Blood sugar 4 -6 %
Controlling These Norms: Feedback Systems Feedback systems include: – Receptor: Senses the change, alerts the control center. – Control center: Determines how to fix the change, sends a message to the effectors. – Effector: Returns the body to normal. – Feedback: All normal message is sent to control center, which shuts down the effectors.
How does a thermostat work?
How does your body react to… • • Being too hot? Being too cold? Eating too much salt? Drinking too much water? How does your body adjust to these changes?
Negative Feedback Loop • A change from “normal” triggers mechanisms that restore “normal” • Resists change • Most common type of feedback loop
Positive Feedback Loops • A process by which a small change is increased • Amplifies change • Usually associated with disease (e. g. addiction, high blood pressure) • Example: Labour – contractions increase until baby pops out, then stop.
Homework • Questions: p. 111 #1, 3, 4, 6
- Slides: 9