1. Feedback Loops
-feedback loops manage homeostasis in the body through the nervous system
-negative feedback is the regulating of a system so that it doesn’t stray too far in one direction
ex: a thermostat that regulates temperature if it gets
too hot or too cold
An example of negative feedback:
-Fat cells produce the hormone leptin when they
become filled
-Leptin is carried by the blood to the brain where it
acts to inhibit the appetite center
-When fat reserves diminish, the concentration of
leptin decreases which causes the appetite center
in the brain to start the hunger stimulus and activate
the urge to eat.

2. Feedback Loops Other examples of negative feedback:
-when you get cold, you shiver to get warmer
-when you get hot, you sweat to get cooler
-when blood sugar levels are too low, the body sends
signals for reserves in the liver and muscles to release
glucose into blood
-when blood sugar levels are too high, the body sends
signals for reserves to take in glucose from the blood

3. Feedback Loops
-positive feedback is the amplification of a signal; a small disturbance continues to grow and grow such that the effect gets larger and larger

4. Feedback Loops -Systems that regulate homeostasis:
-Pancreas secretes insulin that manages blood sugar
levels
-Thyroid gland secretes thyroxine that manages
metabolism
-Pituitary gland (controlled by the hypothalamus)
secretes many different hormones that serve various
purposes:
-growth
-sex organ function
-pregnancy and child birth
-and more!
-Adrenal glands secretes adrenaline manages fight-
or-flight response

5. Feedback Loop Analogy
A thermostat is a useful analogy for a negative feedback loop because it keeps a temperature from getting too cold or too hot. Develop your own analogy for a negative feedback loop. Your analogy can be as crazy as you can imagine.
Requirements:
1. A picture of your analogy
2. A description of how your
analogy is similar to a negative
feedback loop. How does it
prevent things from getting too
extreme?