Pancreatic Receptors & Role of Hormones

Introduction

The regulation of blood glucose levels is a crucial aspect of maintaining homeostasis in the human body. Fluctuations in blood glucose can have serious consequences for various physiological processes. This topic explores the role of pancreatic receptors and the hormones insulin, glucagon, and adrenaline in the negative feedback control of blood glucose levels.

Pancreatic Receptors

1. Blood Glucose Sensing

The pancreas plays a central role in blood glucose regulation. It contains specialised cells, known as pancreatic receptors, that are sensitive to changes in blood glucose levels.

2. Insulin Secretion

When blood glucose levels rise, such as after a meal, pancreatic receptors in the pancreas detect this increase. In response, they signal the release of insulin into the bloodstream.

3. Glucagon Secretion

Conversely, when blood glucose levels drop, pancreatic receptors sense this decrease and trigger the secretion of glucagon from the pancreas.

Role of Hormones in Negative Feedback

1. Insulin

Insulin is a hormone released by the pancreas in response to elevated blood glucose levels. Its primary role is to facilitate the uptake of glucose by cells for energy or storage. When insulin binds to receptors on cell membranes, it allows glucose to enter the cells, reducing the concentration of glucose in the bloodstream.

---

Pancreatic Receptor & Role of Hormone in Negative Feedback

Human Biology

2. Glucagon

Glucagon is another pancreatic hormone, but it has the opposite effect of insulin. It is released in response to low blood glucose levels and stimulates processes that increase blood glucose concentration.

Example: Between meals or during periods of fasting, when blood glucose levels drop, glucagon is released. It promotes the breakdown of glycogen (stored glucose) in the liver into glucose, which is released into the bloodstream. This helps prevent hypoglycemia (low blood sugar).

3. Adrenaline

While insulin and glucagon are the primary hormones involved in blood glucose regulation, adrenaline (epinephrine) also plays a role during specific situations, such as exercise or the 'fight or flight' response.

Example: During physical activity or a stressful event, adrenaline is released from the adrenal glands. It promotes the breakdown of glycogen in the liver into glucose, increasing blood glucose levels. This provides a rapid source of energy to meet the body's increased demands during these situations.

Negative Feedback Control of Blood Glucose

• The regulation of blood glucose through insulin and glucagon represents a classic example of negative feedback control. Negative feedback is a mechanism that maintains a variable (in this case, blood glucose) within a narrow, ideal range.
• When blood glucose levels deviate from the set point (elevated or reduced), the actions of insulin and glucagon work to bring glucose levels back to the normal range. Insulin lowers blood glucose when it's too high, while glucagon raises it when it's too low.

Summary