1. Interdependence of Body Systems
Homeostasis is the process by which the body maintains a stable internal environment.
Our bodies sweat to maintain a stable temperature (to keep us from overheating).

2. Negative Feedback
The body changes an internal condition back to its normal state.
Used by most body systems to keep homeostasis.
Blood pressure is regulated this way.

3. Maintaining Chemical Balance
Negative feedback helps maintain chemical balance.
When glucose levels are too high insluin is secreted by the pancreas.
When glucose levels are too low glucagon is secreted by the pancreas.

4. Positive Feedback Rare in a healthy body.
When change in the body occurs, the positive feedback mechanism does not restore the body to a normal state.
Example: Contractions during childbirth.

5. Blood Clotting Positive feedback
When a blood vessel is cut, it constricts and chemicals are released.
These chemicals cause blood platelets to stick to each other (clot together).
When enough platelets stick together, the hole in the blood vessel is plugged.

6. Questions What is homeostasis?
Which type of feedback is used by most body systems to maintain chemical balance?
Explain what positive feedback is and give an example?
Explain what negative feedback is and give an example?