Glucagon: Definition, Function & Effects

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  • 0:02 Glucagon
  • 0:47 Production
  • 1:56 Glucagon Control
  • 2:48 Lesson Summary
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Lesson Transcript
Instructor: John Williams
In emergency situations, the body has to increase its sugar supply in order to produce energy. In this lesson, we'll discuss glucagon, a key hormone involved in increasing sugar levels.


Imagine that you're walking in the woods, when suddenly, you hear a growling noise! You take off running. As soon as you feel safe, you stop and catch your breath. What could have made that noise? And have you gotten far enough away from it?

In this scenario, your body begins to make changes in order to prepare for an emergency situation. These changes are a part of what is known as the fight-or-flight (or emergency) response, and they require a large amount of energy in order to ensure that you'll survive. While there are numerous physiological changes taking place in most of the body systems, the one that is key to energy production is the release of a hormone known as glucagon.


Glucagon is a peptide, or protein hormone, that is produced by the pancreas. The pancreas is an accessory organ of the gastrointestinal system that produces multiple hormones and enzymes, including bicarbonate and insulin. Glucagon is produced whenever the body needs more sugar for energy production, which is done through cellular respiration. Typically, glucagon is released during fight-or flight responses, as it helps with the release of glucose from the liver.

Upon eating foods with carbohydrates, we often process this material immediately for energy; however, in the event that there is extra sugar remaining after the basic energy needs are met, then these carbohydrates will be stored in the liver as glycogen. It is here that glucagon has its effects.

Glucagon stimulates cells in the liver to release glucose from the glycogen reserves. This increases the amount of glucose in the blood. As such, glucose circulates to different tissues within the body, such as cardiac and skeletal muscles, to provide extra fuel for these increased energy demands.

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