Problem 151 - Objective Biology for NEET

Question

Assertion: Glucagon is a hypoglycaemic hormone Reason: Glucagon stimulates glycogenesis

Step-by-Step Solution

Answer

The assertion and reason are both incorrect.

Step 1: Analyzing the Assertion

Firstly analyze the assertion that glucagon is a hypoglycaemic hormone. Scientifically, glucagon is actually a hyperglycemic hormone, not hypoglycemic. It raises blood sugar levels, rather than lowering them. Therefore, the assertion is incorrect.

Step 2: Analyzing the Reason

Now let's consider the reason given that glucagon stimulates glycogenesis. This is inaccurate as well. Glucagon stimulates a process called glycogenolysis, which is the breakdown of glycogen to glucose. It does not stimulate glycogenesis. Therefore, the reason is also incorrect.

Step 3: Connecting the Analysis

Since both the assertion and the reason are incorrect, the overall statement is incorrect as well. Glucagon is a hyperglycemic hormone and it stimulates glycogenolysis, not glycogenesis.

Key Concepts

Hyperglycemic Hormone

Glucagon is classified as a hyperglycemic hormone, a term that describes its primary function of raising blood sugar levels. When your blood sugar levels are low, glucagon comes into action. It is secreted by the alpha cells in the pancreas. Its main job is to ensure that energy is available during fasting or strenuous activity.

A hyperglycemic hormone works by signaling the liver to carry out certain processes that result in the increase of glucose in the bloodstream. This makes glucagon an essential player in maintaining a balanced glucose level in your blood, which is vital for overall health.

Here's how glucagon functions:

• Increases glucose production by the liver
• Stimulates glycogen breakdown
• Promotes gluconeogenesis (production of glucose from non-carbohydrate sources)
• Supports the availability of glucose for tissues that need it

Understood in this light, glucagon's hyperglycemic effect is crucial for preventing blood sugar levels from falling too low, which can lead to hypoglycemia.

Glycogenolysis

Glycogenolysis is the process by which glucagon encourages the liver to break down glycogen into glucose. Glycogen is a stored form of glucose, and glycogenolysis makes glucose available to be released into the bloodstream.

This breakdown process is crucial during times when your body needs more energy but is not currently receiving it from food intake. By increasing the levels of glucose in the blood, glycogenolysis ensures that your muscles and other organs have the energy they need to function properly.

During glycogenolysis, enzymes activated by glucagon convert glycogen stored in the liver into glucose-1-phosphate, which then undergoes transformation into glucose-6-phosphate. This product is finally converted into glucose, entering the bloodstream to stabilize blood sugar levels.

In simple terms, glycogenolysis serves as a backup, releasing stored energy when immediate dietary glucose is absent.

Blood Sugar Regulation

Blood sugar regulation is a complex process involving hormones like insulin and glucagon to maintain a stable level of glucose in the blood. Glucagon plays a particularly vital role during times of low blood sugar.

When blood sugar is detected to be low, glucagon is released to increase blood sugar levels. It balances the effects of insulin, which works to decrease blood sugar by allowing cells to absorb glucose for energy.

Here's how these processes work together:

• Low Blood Sugar: Glucagon release stimulates liver to release glucose, raising blood sugar.
• High Blood Sugar: Insulin is released to help cells absorb and utilize glucose, lowering blood sugar.

This balance between glucagon and insulin ensures that glucose levels remain within a healthy range, protecting the body from the adverse effects of blood sugar being too high or too low. Effective blood sugar regulation is critical in preventing conditions such as diabetes and ensuring the body's systems operate smoothly.