Glucagon

Definition

Glucagon is a peptide hormone produced by the alpha cells of the pancreas that plays a crucial role in regulating blood glucose levels. When blood sugar levels drop, glucagon is released into the bloodstream to stimulate the liver to convert stored glycogen into glucose, which is then released into the bloodstream. This process is essential for maintaining homeostasis, especially during fasting or intense physical activity, ensuring that the body has a continuous supply of energy.

5 Must Know Facts For Your Next Test

1. Glucagon is released when blood glucose levels fall below normal, usually below 70 mg/dL.
2. The hormone promotes glycogenolysis and gluconeogenesis in the liver, increasing blood glucose levels back to normal.
3. Glucagon works in opposition to insulin; while insulin lowers blood glucose, glucagon raises it, creating a balance in glucose homeostasis.
4. It can also stimulate lipolysis, promoting the breakdown of fat stores for energy when glucose levels are low.
5. In addition to its role in glucose regulation, glucagon can influence other hormones and metabolic processes throughout the body.

Review Questions

• How does glucagon function to regulate blood sugar levels when they drop?
  • Glucagon functions to regulate blood sugar levels by stimulating the liver to convert glycogen back into glucose and release it into the bloodstream. When blood sugar levels drop below a certain threshold, glucagon is secreted by the alpha cells of the pancreas. This leads to increased glycogenolysis and gluconeogenesis, processes that raise blood glucose levels and restore them to normal range, thus playing a critical role in maintaining energy balance.
• Compare and contrast the roles of glucagon and insulin in maintaining glucose homeostasis.
  • Glucagon and insulin are both key hormones in regulating blood glucose levels but have opposite effects. While glucagon is released when blood sugar levels are low, prompting the liver to release glucose into the bloodstream through glycogenolysis and gluconeogenesis, insulin is released when blood sugar levels are high. Insulin facilitates the uptake of glucose by cells and promotes its storage as glycogen. Together, these hormones maintain glucose homeostasis by ensuring that energy needs are met under varying physiological conditions.
• Evaluate how an imbalance in glucagon secretion might impact overall metabolism and health.
  • An imbalance in glucagon secretion can lead to significant metabolic disruptions. Excessive glucagon production can cause hyperglycemia, leading to diabetes mellitus if not regulated properly. Conversely, insufficient glucagon secretion may result in hypoglycemia, which can cause symptoms such as dizziness, weakness, and confusion. These imbalances highlight the importance of glucagon in energy metabolism and underscore its role in maintaining overall metabolic health and homeostasis within the body.

Related terms

Insulin:

A peptide hormone produced by the beta cells of the pancreas that lowers blood glucose levels by facilitating cellular uptake of glucose.

Glycogenolysis: The biochemical process by which glycogen is broken down into glucose, primarily occurring in the liver, stimulated by glucagon.

Homeostasis:

The process through which biological systems maintain stability while adjusting to changing external conditions, crucial for overall physiological balance.