How Does Glucagon Work In The Body?
Glucagon is a hormone that is produced by alpha cells in your pancreas. It holds one of the pillars in the metabolism of the human body and regulates glucose levels in your blood. Let’s have a precise overview of how glucagon works.
Function of Glucagon
Glucagon is the main catabolic hormone of the human body. Simply put, it breaks larger complex molecules into smaller, simpler units for the utility, transport, or synthesis of new molecules.
When does your pancreas know it's time to produce and release glucagon in the blood? Hypoglycemia, i.e., decreased blood sugar levels, is the signal.
Our bodies use glucose as a source of energy. And glucose is normally present in our blood, ready to be taken up by the cells anywhere in the body. Cells break down glucose and extract energy from it. So when the glucose in our blood gets used up and the levels drop, this is the signal that demands the replenishment of glucose in a sufficient amount in the bloodstream.
Modes of Action of Glucagon
Glucagon has a wide variety of functions in different organs of your body.
The liver is the metabolic hub of your body. We can count it as the third most crucial organ of your body. Glucagon binds to its receptors in the liver and causes major changes in its biochemical function. These changes are:
- Our body stores Glucose in the form of Glycogen in the liver. When the Glucagon arrives at the liver, it starts a process called Glycogenolysis ('lysis' means breakdown). This releases Glucose molecules which replenishes your blood sugar levels.
- It increases the formation of new glucose molecules from amino acids (the building components of proteins) in a process called Gluconeogenesis ('Genesis' means formation).
- It increases the breakdown of Fats (Lipids) in a process called Lipolysis, which results in increased amounts of Fatty Acids, the building units of all Fats. This process also produces some energy.
2. Fatty Tissues
The same Lipolysis process takes place in your body's fatty tissues. The fatty acids released in Lipolysis are used in a process called oxidation to produce energy. It is by virtue of Lipolysis under the effect of Glucagon and other stress hormones that you can burn your body fat to lose weight.
Glucagon acts on the brain to produce the feeling of fullness and decreased hunger to reduce food intake when your body has consumed enough sugar.
Glucagon also acts on the pancreas to decrease insulin secretion, which produces the opposite effects of Glucagon. The absence of insulin allows glucagon to carry out its functions uninterruptedly.
Normal Glucagon Levels On Lab Tests:
Since we don't want Glucagon to go haywire and wreak havoc in our bodies, there exists a feedback control system of Glucagon and Insulin to keep its levels in your body in check. This keeps the level of Glucagon in the range of 50-100 picograms (pg) on most of the lab reports.
Clinicians do not normally advise glucagon tests, except in case of an uncommon illness affecting glucagon production.
Role Of Glucagon In Fasting And Starvation:
Your brain utilizes 20% of the energy produced in your whole body, considering it only counts for 2% of your total body weight. However, the brain can only utilize glucose as fuel. So when fasting for 24-48 hours and starvation results in marked hypoglycemia (low blood sugar), your brain functions start getting affected, and you feel dizzy and confused.
Here, glucagon comes to the rescue. After the glycogen stores in the liver start depleting, glucagon starts acting on your muscles. It increases the breakdown of proteins (Proteolysis) to produce Amino Acids. These Amino Acids are then used to synthesize Glucose (Gluconeogenesis) in the Liver. That's how Glucagon deals with the Glycogen and glucose shortage crisis.
Glucagon’s Role In Stress:
Glucagon is released in a stressful situation when your body’s metabolic demands are increased. During that time, blood glucose levels will remain high as it is continuously utilized by the body to generate energy.But as soon as you're out of that stressful environment, glucagon levels go down to normal, and so does the glucose present in the blood. That's why you can maintain your performance and activity in the heat of the moment, but afterward, you feel tired and exhausted.
Pharmaceutical Glucagon: Injections And Nasal sprays
Synthetic Glucagon is available in various formulations. They are administered in the form of nasal sprays or injections. These are used in emergency situations when blood glucose levels are dangerously low in Type 1 Diabetes. Such patients might suddenly collapse after taking insulin which can sometimes cause severe Hypoglycemia. Administering Glucagon will allow the liver to release stored Glucose to maintain blood glucose levels.