Question

Which of the following statements about glucagon is true? a. Glucagon causes glycogen to break down to form glucose. b. Glucagon secretion is highest following a heavy meal. c. Glucagon promotes the uptake of glucose by liver and muscle cells. d. Glucagon works with cortisol to lower blood glucose levels.

Short answer

a. Glucagon causes glycogen to break down to form glucose.

Step-by-step solution

- Understanding Glucagon

Glucagon is a hormone produced by the pancreas. Its main role is to increase blood glucose levels by promoting the breakdown of glycogen to glucose in the liver.

- Analyzing the Statements

Read each statement carefully to determine which one accurately describes the function of glucagon: a. Glucagon causes glycogen to break down to form glucose. b. Glucagon secretion is highest following a heavy meal. c. Glucagon promotes the uptake of glucose by liver and muscle cells. d. Glucagon works with cortisol to lower blood glucose levels.

- Evaluating the Options

Evaluate each statement based on the role of glucagon: - Statement a is correct because glucagon stimulates glycogen breakdown (glycogenolysis) in the liver, forming glucose. - Statement b is incorrect because glucagon secretion is usually higher when blood glucose levels are low, not after a heavy meal. - Statement c is incorrect as glucagon does not promote the uptake of glucose by liver and muscle cells; this is the role of insulin. - Statement d is incorrect because both glucagon and cortisol raise blood glucose levels, not lower them.

- Choosing the Correct Statement

Based on the evaluations, the true statement is: a. Glucagon causes glycogen to break down to form glucose.

Key concepts

hormonal regulation

Hormones are crucial in regulating various functions in the body, especially in maintaining homeostasis. The pancreas produces several important hormones, and one of them is glucagon. This hormone plays a significant role in hormonal regulation by ensuring that blood glucose levels remain within a healthy range.
When blood glucose levels drop, the pancreas secretes glucagon to bring them back up. This process involves several steps:

• First, glucagon binds to receptors on liver cells.
• Next, it triggers a cascade of events that lead to the conversion of glycogen to glucose.
• Finally, the glucose is released into the blood, raising blood glucose levels.

Understanding the role of glucagon in hormonal regulation helps us appreciate how the body maintains balanced blood sugar levels, preventing both hypoglycemia and hyperglycemia.

glycogenolysis

Glycogenolysis is a metabolic process where glycogen, a stored form of glucose, is broken down into glucose. This process is crucial during fasting, exercise, or whenever the body needs an extra boost of energy. Here’s how it works:

• Glucagon, released by the pancreas when blood glucose levels are low, initiates glycogenolysis.
• The hormone binds to receptors on liver cells, signaling enzymes to break down glycogen.
• The resultant glucose molecules are then released into the bloodstream, providing energy to cells throughout the body.

This mechanism ensures that we have a constant supply of glucose, especially during times when we are not eating and helps keep our blood sugar levels stable.

pancreatic hormones

The pancreas is an organ that plays a vital role in digestion and blood sugar regulation by releasing important hormones. There are two main hormones produced here: insulin and glucagon.
Insulin is released when blood glucose levels are high, promoting the uptake of glucose by liver, muscle, and fat cells. This helps lower blood glucose levels.
On the other hand, glucagon is released when blood glucose levels are low. It triggers the breakdown of glycogen stores in the liver to release glucose into the bloodstream.

These two hormones act in opposition but together maintain blood glucose homeostasis. When one goes out of balance, various health issues, such as diabetes, can occur.

blood glucose levels

Maintaining proper blood glucose levels is crucial for overall health. Blood glucose is the primary source of energy for our cells, and its levels are tightly regulated by hormones like insulin and glucagon.
When you eat a meal, carbohydrates are broken down into glucose, which enters the bloodstream. To manage this influx, the pancreas releases insulin, allowing cells to take up glucose and use it for energy.
Conversely, when you haven’t eaten for a while, blood glucose levels drop. The pancreas then secretes glucagon, signaling the liver to release glucose from its glycogen stores.

• By understanding these processes, we can see how our bodies maintain energy levels and keep blood glucose within a healthy range, avoiding issues like hypoglycemia or hyperglycemia.