How do insulin and glucagon work in the body?

How do insulin and glucagon work in the body?
Islet cells found in the pancreas release insulin and glucagon. The pancreas contains clusters of islet cells (Langerhans) of several types, including alpha cells, responsible for glucagon release, and beta cells for insulin.
Insulin and glucagon hormones regulate the blood sugar level in the body. If the level of one hormone fluctuates from its optimal range, it results in fluctuating blood sugar levels.
The body makes glucose from food carbohydrates, which is the significant sugar providing energy to the body. Blood sugar levels tell about the body's health and efficiency in utilizing glucose. Its level fluctuates throughout the day, but insulin and glucagon regulate it within a healthy range.
Blood sugar levels remain high when the body doesn't convert enough glucose. Insulin reduces this level by absorbing glucose and using its energy for proper cell functioning. When blood sugar levels are down, the pancreas releases glucagon that signals the liver to release stored glucose and normalizes blood sugar levels.
Let’s discuss how they work together to keep blood glucose levels at their optimal point.

1.  How Does Insulin Work in the Body?

Food contains carbohydrates which are converted to glucose during digestion. Most of its portion is sent to the bloodstream resulting in higher glucose levels in the blood than usual. Glucose is the primary cellular energy source. Insulin permits cells of muscles, liver, and adipose tissues (fats) to absorb these molecules and use them for their excellent performance in proper body functioning. Higher blood sugar levels signal the pancreas to start producing insulin which ultimately asks cells to take a maximum of it. Blood glucose levels go down as cells consume it.
Cells need energy for performing cell tasks, but most of them cannot do so without insulin, allowing glucose to access cells. It attaches itself at the insulin receptor sites on the cell's surface, instructing cells to open for the entry of glucose molecules.
Insulin stays at low levels in cells and a spike in its level signals to the liver about high blood glucose levels. Resultantly, the liver absorbs excess glucose by converting it to glycogen, the stored form of glucose. Without insulin, cells cannot use glucose as fuel and start malfunctioning.
At low sugar levels, glucagon signals the liver to convert glycogen to glucose to maintain the blood glucose level again.
Insulin is also responsible for healing an injury by granting amino acids to the muscles. These helps build proteins in muscle tissues. It means low levels of insulin may disturb the healing power of muscles. Plus, in its metabolic effects, it stops proteins and fats breakdown.

2.  How is Insulin Controlled?

The primary function of insulin is to enter glucose in the cells and maintain its regular availability in blood for further use. The process is regulated in healthy people to create a balance in food intake and satisfy body needs. Other hormones found in the liver and gut regulate this complex process with different hormones.
Our body increases blood glucose levels by absorbing it from the gut and releasing it into the bloodstream. This rise results in insulin release to move this glucose in cells. Insulin production becomes lower after an adequate amount of glucose is introduced into the cells. However, proteins and other gut hormones also cause insulin to release.
Adrenaline, a hormone released during stress, affects insulin secretion badly and retains a higher blood sugar level to deal with stress.

3.  How Does Glucagon Work in the Body?

Alpha cells are responsible for secreting glucagon surrounding beta cells, releasing insulin, making a solid relationship between them. Glycogen counteracts to minimize the effects of insulin. Glucagon plays its role in several ways:

3.1. Glycogenolysis

 The conversion of glycogen to glucose in the liver is directly released into the bloodstream.

3.2. Gluconeogenesis

The process in which amino acid molecules are converted into glucose.

3.3. Homeostasis by Maintaining Sugar Level

It lowers glucose storage by the liver and secret it to the blood to maintain the glucose level.
Poor nutrition or skipping meals lead to reduced sugar levels. Further, after five to six hours, blood sugar levels go down, signalling the pancreas to release glucagon. The liver stores excess glucose when present to power cells when the body needs it. Also, the liver ensures the maintenance of glucose levels during sleep, workouts, and meals.
Islet cells release glucagon at low glucose levels that ultimately signal the liver to convert stored glycogen to glucose, making it available in the bloodstream for cells to absorb. Now, insulin gets attached to the receptor sites on the cells and allows glucose to enter the cells.
Glucagon also acts on adipose tissues and break stored fats in the bloodstream when needed.

4.  How is Glucagon Controlled?

Low blood sugar levels, adrenaline hormones, and protein-rich food stimulate glucagon secretion. Pancreas cells detect the need for fuel (glucose) and the number of carbs in meals to decide either body needs glucagon or not. Plus, its presence is beneficial for longer terms as it starts converting fats to glucose in a limited sugar supply to the body.

5.  How Do Insulin and Glucagon Work Together?

The pancreas releases glucagon to stop blood sugar levels dropping too down in a condition known as hypoglycemia and insulin in hyperglycemia to stop the further rise in blood glucose levels.
Both hormones work in a cyclic pattern known as a negative feedback manner. Glucagon involves increasing blood sugar levels, while insulin lowers it by helping cells utilize excessive glucose. This loop is continuously in motion, ensuring the adequate availability of glucose supply to the cells.
Together they help homeostasis, which keeps bodily functions in a steady state. One event trigger or suppress the other to keep balanced sugar levels. For instance, insulin is high in the body with the presence of high sugars in the blood and higher glucagon with dropped levels of body sugar level. This balance offers the body sufficient energy to prevent nerve damage caused by constant high blood glucose levels.

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