Feedback Loops

What is a negative feedback loop?A negative feedback loop is a cycle where the final outcome stops the whole cycle from continuing any more.

Negative Feedback Loops – Real Life Example:1) You go to AVID class.2) Mrs. Cabrera makes you check your grades.3) You realize you are failing 2 classes.4) You start to work harder and ask your teachers for

missing assignments and make up work.5) You grades go up.6) You stop worrying about missing assignments and

make up work.

Negative Feedback Loops – Real Life Example:1) You get dehydrated.2) Your brain tells you you’re thirsty.3) You drink water.4) You body becomes hydrated (has enough water)

again.5) Your brain stops telling you you’re thirsty.6) You no longer feel thirsty, so you stop drinking.

Processing Piece: Are each of the following examples of negative feedback loops?

1. A person realizes they have gained 20 pounds and starts dieting until they are back to normal.

2. When you feel tired, you sleep until you don’t feel the need to sleep anymore.

3. If your blood sugar gets too high, your body releases insulin until it drops to a normal level.

4. You’re driving and your car starts drifting right when it’s not supposed to. You turn the steering wheel left until your car is back in the lane where it’s supposed to be.

5. You’re running the mile. Even though you feel tired, you make yourself keep running.

What are some examples of negative feedback loops in the body?

Erythropoiesis (producing red blood cells):1. Level of oxygen in blood gets too low.2. Kidney notices oxygen in the blood is too low.3. Kidney sends a hormone signal to bone marrow.4. Bone marrow produces more blood cells.5. Thanks to the new red blood cells, there is more

oxygen in the blood now, so the body stops making new blood cells.

What are examples of negative feedback loops in the body?

Blood glucose control - insulin:1. Blood glucose (sugar) gets too high.2. Pancreas notices blood glucose is too high.3. Pancreas releases more insulin.4. Insulin travels to skeletal muscle, liver, and fat cells. 5. Insulin makes these cells store glucose (a

monomer) as glycogen (a polymer).6. Blood glucose goes down, so the pancreas stops

making insulin.

Processing Piece:

• Draw a picture to illustrate this process.

What are examples of negative feedback loops in the body?

Blood glucose control - glucagon:1. Blood glucose (sugar) gets too low.2. Pancreas notices blood glucose is too low.3. Pancreas releases more glucagon.4. Glucagon travels to skeletal muscle, liver, and fat cells. 5. Glucagon makes these cells break down glycogen (a

polymer) to produce glucose (a monomer).6. Blood glucose goes down, so the pancreas stops

making glucagon.

Why are negative feedback loops so helpful?• Negative feedback loops help the body maintain

homeostasis.• If something goes out of balance, the body reverses

it, until it gets back to normal.

What is a positive feedback loop?• A positive feedback loop is a cycle where the final

outcome of a series of reactions makes the whole cycle happen even more.

What is an example of a positive feedback loop?• Childbirth:– Oxytocin is released.– This stimulates (increases) contractions.– Contractions make the body release more oxytocin.– More oxytocin stimulates even more contractions.

Exit Ticket1. Using COMPLETE SENTENCES, describe an example

of a negative feedback loop. BE DETAILED.2. In a COMPLETE SENTENCE, explain why negative

feedback loops are important.