Review: Positive and Negative Feedback Loops
1. What are the two types of feedback loops
illustrated in Model 1?
a. ____________________________
b. ___________________________
2. Which of the feedback loops in Model 1 would
be most useful for AMPLIFYING a condition that is advantageous for the organism?
________________________________________________________________
3. Which of the feedback loops in Model 1 would be most useful for STOPPING a condition that is detrimental or
limiting a condition to specified levels? ________________________________________________________
Review Questions:
1. Describe what homeostasis is IN YOUR OWN WORDS, and give an example. __________________
_____________________________________________________________________________________________
2. What is the receptor’s role in maintaining homeostasis? AND give an example of a receptor. ________________
_____________________________________________________________________________________________
3. What is the control center’s role? ________________________________________________________________
4. Based on your answer to #3, what type of neuron is probably found in the control center?__________________
5. Based on your answer to #2, what type of neuron is probably found in a receptor?_________________________
Use the graph below for the rest of this worksheet
Look at the graph above. Imagine that the horizontal line represents a body temperature of
98.6 degrees.
1) When running in PE class, you get warm. Your body temperature starts to raise (above
homeostasis). Label this on the graph as “stimulus: too warm”
2) Because you are hot, your body starts to sweat, and cools you back down to 98.6 degree.
Label this on the graph as “response: sweat”
3) You are still sweaty when you come to physiology, which has the AC on. You start to get
cold, and your body temp drops below 98.6 degrees. Label this as “stimulus: too cold”
Review: Positive and Negative Feedback Loops
1. What are the two types of feedback loops
illustrated in Model 1?
a. ____________________________
b. ___________________________
2. Which of the feedback loops in Model 1 would
be most useful for AMPLIFYING a condition that is advantageous for the organism?
________________________________________________________________
3. Which of the feedback loops in Model 1 would be most useful for STOPPING a condition that is detrimental or
limiting a condition to specified levels? ________________________________________________________
Review Questions:
1. Describe what homeostasis is IN YOUR OWN WORDS, and give an example. __________________
_____________________________________________________________________________________________
2. What is the receptor’s role in maintaining homeostasis? AND give an example of a receptor. ________________
_____________________________________________________________________________________________
3. What is the control center’s role? ________________________________________________________________
4. Based on your answer to #3, what type of neuron is probably found in the control center?__________________
5. Based on your answer to #2, what type of neuron is probably found in a receptor?_________________________
Use the graph below for the rest of this worksheet
Look at the graph above. Imagine that the horizontal line represents a body temperature of
98.6 degrees.
1) When running in PE class, you get warm. Your body temperature starts to raise (above
homeostasis). Label this on the graph as “stimulus: too warm”
2) Because you are hot, your body starts to sweat, and cools you back down to 98.6 degree.
Label this on the graph as “response: sweat”
3) You are still sweaty when you come to physiology, which has the AC on. You start to get
cold, and your body temp drops below 98.6 degrees. Label this as “stimulus: too cold”
4) You stop sweating, your body starts to shiver and your blood vessels constrict. Your temperature raises
back up to 98.6. Label this as “response: constrict blood vessels.”
5) Is this graph illustrating positive or negative feedback? ______________________________________
6) Why / How can you tell? ______________________________________________________________
_____________________________________________________________________________________________
7) Label “HOMEOSTASIS” on the graph above. Describe homeostasis for temperature:
_____________________________________________________________________________________________
Feedback Loop Graphs
Graphs can be used to record the changes in the body when it deviates from homeostasis.
Graph A:
Graph B:
Glucose levels in the blood after eating:
Blood clotting factor levels after an injury:
1. ________________ feedback loops continue to move away from homeostasis after a
stimulus moves the body away from homeostasis.
2. ________________ feedback loops move the body back towards the homeostasis (set
point) after a stimulus had moved the body away from homeostasis.
3. _________________ type of feedback loop will help keep the body operating within a
narrow range. For example, the human body’s temperature operates under homeostatic
conditions of 98.6 degrees. When the body gets too warm or too cool, this type of feedback
loop brings the body back to 98.6 degrees homeostasis.
5. Which is controlled by a negative feedback loop? Graph A or Graph B? ________________
6. It’s lunchtime, so you eat a sandwich. When the food passes through your stomach and
into your intestine, your brain receives a signal causing you to feel full. After this message, you
stop eating and give your food to a friend. Is this an example of positive or negative feedback?
_____________________________________________________________________________
7. Describe why Graph A increases, reaches a point, and then decreases.
_____________________________________________________________________________
_____________________________________________________________________________
4) You stop sweating, your body starts to shiver and your blood vessels constrict. Your temperature raises
back up to 98.6. Label this as “response: constrict blood vessels.”
5) Is this graph illustrating positive or negative feedback? ______________________________________
6) Why / How can you tell? ______________________________________________________________
_____________________________________________________________________________________________
7) Label “HOMEOSTASIS” on the graph above. Describe homeostasis for temperature:
_____________________________________________________________________________________________
Feedback Loop Graphs
Graphs can be used to record the changes in the body when it deviates from homeostasis.
Graph A:
Graph B:
Glucose levels in the blood after eating:
Blood clotting factor levels after an injury:
1. ________________ feedback loops continue to move away from homeostasis after a
stimulus moves the body away from homeostasis.
2. ________________ feedback loops move the body back towards the homeostasis (set
point) after a stimulus had moved the body away from homeostasis.
3. _________________ type of feedback loop will help keep the body operating within a
narrow range. For example, the human body’s temperature operates under homeostatic
conditions of 98.6 degrees. When the body gets too warm or too cool, this type of feedback
loop brings the body back to 98.6 degrees homeostasis.
5. Which is controlled by a negative feedback loop? Graph A or Graph B? ________________
6. It’s lunchtime, so you eat a sandwich. When the food passes through your stomach and
into your intestine, your brain receives a signal causing you to feel full. After this message, you
stop eating and give your food to a friend. Is this an example of positive or negative feedback?
_____________________________________________________________________________
7. Describe why Graph A increases, reaches a point, and then decreases.
_____________________________________________________________________________
_____________________________________________________________________________