Hormones + Neg Feedback

What is a hormone?

A chemical messenger released into the blood that travels to target cells.

Q: What is homeostasis?

The maintenance of a stable internal environment in the body.

Q: Why is homeostasis important?

It keeps conditions stable so enzymes and body systems can function properly.

Q: What is a target cell?

A cell with specific receptors that respond to a hormone.

Q: What does the pancreas do?

Produces insulin and glucagon to regulate blood glucose levels.

Q: Where is the pancreas located?

In the upper abdomen behind the stomach.

Q: What hormones does the pancreas produce?

Insulin and glucagon.

Q: What does insulin do?

Lowers blood glucose levels.

Q: When is insulin released?

When blood glucose is too high (e.g. after eating).

Q: How does insulin lower blood glucose?

Cells absorb glucose and the liver stores excess glucose as glycogen.

Q: Which cells produce insulin?

Beta cells in the pancreas.

Q: What does glucagon do?

Raises blood glucose levels.

Q: When is glucagon released?

When blood glucose is too low.

Q: How does glucagon raise blood glucose?

It causes the liver to break down glycogen into glucose and release it into the blood.

Q: Which cells produce glucagon?

Alpha cells in the pancreas.

Q: How do insulin and glucagon work together?

They have opposite effects to maintain blood glucose homeostasis.

Q: What is the goal of insulin and glucagon?

To keep blood glucose levels stable.

Q: What is negative feedback?

A control system where the body reverses a change to bring a level back to normal.

Q: What happens when blood glucose rises above normal?

Pancreas releases insulin.

Q: What does insulin do in this case?

Cells absorb glucose and the liver stores glucose as glycogen.

Q: What happens after insulin acts?

Blood glucose returns to normal and insulin production slows (feedback loop ends).

Q: What happens when blood glucose drops too low?

Pancreas releases glucagon.

Q: What does glucagon do in this case?

Liver breaks down glycogen into glucose and releases it into the blood.

Q: What happens after glucagon acts?

Blood glucose returns to normal and glucagon production slows.

Q: What is the key idea of negative feedback?

The body detects a change and triggers a response that reverses it to restore normal levels.