Insulin and glucagon (video) | Bioenergetics | Khan Academy
Your body's regulation of blood glucose is an amazing your body's use or production of insulin and glucagon are off. Insulin and glucagon are potent regulators of glucose metabolism. .. The vital relationship between insulin and glucagon has suggested additional areas for. Glucagon binds to the glucagon receptor, a G for the release of glucose phosphate from glycogen polymers. This process is reversible in the absence of glucagon (and thus, the presence of insulin).
Function[ edit ] Glucagon generally elevates the concentration of glucose in the blood by promoting gluconeogenesis and glycogenolysis. Liver cells hepatocytes have glucagon receptors. When glucagon binds to the glucagon receptors, the liver cells convert the glycogen into individual glucose molecules and release them into the bloodstream, in a process known as glycogenolysis. As these stores become depleted, glucagon then encourages the liver and kidney to synthesize additional glucose by gluconeogenesis.
Glucagon turns off glycolysis in the liver, causing glycolytic intermediates to be shuttled to gluconeogenesis. Glucagon also regulates the rate of glucose production through lipolysis. Glucagon induces lipolysis in humans under conditions of insulin suppression such as diabetes mellitus type 1.
In invertebrate animals, eyestalk removal has been reported to affect glucagon production. Excising the eyestalk in young crayfish produces glucagon-induced hyperglycemia.
The role of glucose, insulin and glucagon in the regulation of food intake and body weight.
Glucagon binds to the glucagon receptora G protein-coupled receptorlocated in the plasma membrane. The alpha subunit specifically activates the next enzyme in the cascade, adenylate cyclase. So glucagon does the opposite, it releases glucose from storage. So now that we know how the release of glucagon and insulin can affect blood-glucose levels, let's focus in and see how that happens.
So let's start with insulin, and that does a number of things to glucose. But remember, that at the end of the day, all we're doing is storing it. Just remember, insulin causes storage. So, the first thing that insulin does to glucose, is cause it to undergo a process known as "glycolysis. It's an irreversible process. It's irreversible, alright, irreversible down here. Because it converts glucose into ATP, which is the most basic unit of energy that we use in the body.
And that's an important distinction. ATP is energy to be used anywhere in the body. Okay, instead of storing the energy of glucose in ATP, insulin can cause glucose to undergo what's called "glycogenesis. And glycogen is just a heavily-branched polymer, or molecule that has a whole bunch of glucose molecules stacked on top of it. And this is just energy to be stored in the short-term in mainly the liver, or muscle tissue.
So mainly, liver or muscle. And this is a reversible process, because once we make glycogen, we can break it down and release glucose as well. Finally, the last thing insulin can cause glucose to do, is undergo "lipogenesis.
- How Insulin and Glucagon Work
- The role of glucose, insulin and glucagon in the regulation of food intake and body weight.
- Normal Regulation of Blood Glucose
So this is irreversible, where we store glucose as lipid, and the key here is that we are taking the energy of glucose, and we are storing it long term. Long term, in what's called "adipose tissue. Now what about glucagon? What are the processes it uses to release energy or glucose into the blood stream?
Let's put it this way. If we're releasing glucose into the blood stream, my question is, what are we releasing it from? Well, the first thing we can release it from, is glycogen. And we just talked about this. We can form glycogen using insulin. Or, if there's a lot of glucagon around, we can have what's called "glyco," "glycogenolysis. The other thing we can release glucose energy from, is, or rather I should say, are, amino acids.
Amino acids can undergo a process known as "gluconeogenesis. Now finally, the last thing glucagon can do, is to take fatty acid, so fatty acid or your lipid, and instead of converting it to glucose, glucagon will take the fatty acid, and turn it into these things that are called "ketone bodies.
And it does so through a process known as "keto," short for "ketone," "genesis," meaning "to generate ketone bodies. And it's kind of a funky thing that happens within the body, because it's what we do when we're in our starvation mode.
How insulin and glucagon work to regulate blood sugar levels
When we're not getting the right amount of nutrients of some reason or another. And the reason why this is sort of a last resort, is because ketone bodies are very unique, in that they are energy, forms of energy to be used only, only by the heart and brain. Ketone bodies don't really supply energy anywhere else. So that's why it's sort of a last minute starvation mechanism to provide energy where it's most critically needed to help us survive.
So you can sort of see here that there's a tug of war game that goes on between insulin and glucagon.
In fact, insulin itself, when it's released into the blood, will inhibit the release of glucagon. Which just goes to show you how opposite their end goals really are. And there's a lot more to talk about how insulin is released, or how glucagon is released and where it comes from, this is a great overview of what they end up doing in the body.