1. Ch. 1.1 Notes
Homeostasis

2. Characteristics of Living Things
Must have ALL of these:
Orderly structure (cells & DNA)
Reproduces (species)
Grows & develops (needs food & water)
Adjust to surroundings (stimulus/response & homeostasis)
Adapt & evolve due to changes in the environment
This should be a review for you

3. What is homeostasis?
Homeostasis: the process of maintaining a stable internal environment (in your body/cells)
(without homeostasis, organisms would die!)

4. What does homeostasis keep stable?
Body temperature
Heart rate
Blood pressure
Blood sugar levels

5. Homeostasis Video
Homeostasis video clip about body temperature (7 mins)
ource/tdc02.sci.life.reg.fevervid/fev er/#.Wata1FWGPcs

6. How does it keep things stable?
Negative feedback tends to stabilize a system, bringing things back to normal
Example: shivering in response to body cooling off during cold weather
Example: sweating in response to body heating to cause evaporation & body cooling.

7. Negative Feedback
Negative feedback controls sugar levels in the bloodstream as well.
Video clip on how sugar levels are regulated in the body:
-body/systems/endocrine/adam htm

8. Regulation of Blood Sugar Levels

9. Positive Feedback
Positive feedback: when the feedback causes the change to continue increasing in the same direction.
(i.e. we want the condition to continue) Ex: hormone (oxytocin) that causes contractions during pregnancy. Contractions trigger more hormone production, which causes more contractions, etc.
Non Example: if the thermostat's response to a dropping temperature was to switch off the heater or to switch on the air conditioner (chiller) to continue making it even colder! (This is NOT what happens!)
Environmental/Ecological problems.

10. Homeostasis Lab Overview