Homeostasis = the maintenance of a constant internal environment Examples: 1. Blood glucose concentration ≅ 0.01% 2.Blood pH ≅ 7.4 (slightly basic) 3. BP ≅ 120/80 4. Blood Temp. ≅ 37°C 5. CO2 levels in our blood stimulate breathing

The body’s internal environment MUST have certain conditions within tolerable limits to continue healthy functioning. These conditions are maintained by negative feedback. Negative feedback = a process that causes a decrease in a reaction; in response to a stimulus Negative feedback counteracts the stimulus.

Stimulus = a detectable change in the internal or external environment

Positive feedback = a process that causes amplification of a reaction; in response to a stimulus Positive feedback amplifies the body’s response to a stimulus. Ex). Childbirth

Final note: Negative feedback stabilizes a system. Positive feedback leads to instability.