1. Homeostasis and Feedback Loops

2. Homeostasis
Homeostasis is the regulation and maintenance of the internal environment of the body despite changes outside the body

3. What is a feedback loop?
A loop system in which the system responds to change, either in the same direction (positive feedback) or in the opposite direction (negative feedback)

5. Feedback Loops 1. Stimulus: a change in the system.
2. Sensor: the change is detected.
3. Control: a response to the change.
4. Effector: the effect of the response.

6. Feedback Loops sensors gather data
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

7. Feedback Loops

8. Positive Feedback Loops
Positive feedback loops respond by promoting/increasing change.

9. Nursing Positive Feedback Loop
A baby begins to suckle her mother's nipple and a few drops of milk are released (the stimulus).
This encourages the baby and releases a hormone in the mother which further stimulates the release of milk (the response).
The hungry baby continues to suckle, stimulating more milk release until she stops.

10. Negative Feedback Loops
Feedback loop compares current conditions to set ranges.
Negative feedback loop stops/reduces the change.

11. Respiration Negative Feedback Loop

12. Glucose Negative Feedback Loop

15. When the level of carbon dioxide in the blood is too high, the excess carbon dioxide reacts with water and produces carbonic acid. The carbonic acid causes the blood pH to become more acidic. When the blood pH becomes too acidic, chemoreceptors in the brain instruct the body to react and maintain homeostasis in blood pH. Which of these responses by the body would eliminate the excess carbon dioxide and help maintain homeostasis in blood pH?
A Increasing the body temperature by shivering
B Increasing glucose levels in the blood
C Breathing more deeply and frequently
D Decreasing the heart rate