1. Section 28-2 “Homeostasis”
Write everything that is
underlined

2. KEY CONCEPT Homeostasis is the regulation and maintenance of the internal environment of the body

3. I. Homeostasis Conditions within the body must remain within a narrow range – like your body temperature
a. Homeostasis involves keeping the internal environment within set ranges

4. control center receives data, sends messages
b. Control systems help maintain homeostasis.
pore
sweat
glands
hair
follicle
muscle
goose
bump
sensors gather data
control center receives data, sends messages
communication system delivers messages to target organs, tissues
targets respond to change

5. II. Feedback Loops
a. Negative feedback loops are necessary for homeostasis
Feedback compares current conditions to set ranges.
Negative feedback stops the change

6. b. Negative Feedback Loop Example:
O2 / CO2 level returns to normal
Holding breath,
CO2 levels rise
Control system forces exhale, inhale

7. growth hormones stimulate cell division
c. Positive feedback increases change
Example: Torn blood vessel stimulates release of clotting factors
platelets
fibrin
white blood cell
red blood cell
blood vessel
clot
growth hormones stimulate cell division