Hi. In this video, we'll be talking about blood sugar homeostasis. Like other properties of the body, blood glucose levels need to be carefully monitored and regulated. And things can go really wrong when this homeostasis system is disrupted. As is the case with the disease diabetes mellitus, that actually affects nearly 10% of the American population. This disease disrupts blood sugar homeostasis, and it's due to problems with the hormone, insulin. Blood sugar homeostasis is going to be in large part a balancing act of the two hormones, insulin and glucagon. We'll get to what they do in just a second. First, I want to talk about the two types of diabetes, type 1 and type 2. Type 1 is when the pancreas, the gland that produces and secretes insulin, fails to produce sufficient quantities. Oftentimes, this is due to an autoimmune reaction that actually destroys the cells of the pancreas responsible for producing insulin. Now, type 2 is thought of as insulin ins, in the insulin insensitivity. That is a tongue twister. So, basically, with type 2, the cells of the body fail to properly respond to the hormone signal from insulin.
So, what do insulin and glucagon do? Well, both of these hormones are coming from the pancreas, which is this lovely organ here. And the pancreas has many roles in digestion. And again, it also plays a crucial role in blood sugar homeostasis. Now, when you have high blood sugar, your pancreas gets a signal, and it releases insulin. Insulin is going to travel to the tissues of the body and the liver, and it's going to cause your muscles and your liver to take up this excess glucose that's in your blood. So, glucose is stored in animals as this highly branched structure called Glycogen. So, this is sometimes referred to as glycogenesis, the creation of glycogen. And it's going to happen in response to insulin and occurs specifically in the muscles and the liver. Now, when you have low blood sugar pancreas gets a signal and this time it's going to respond by releasing the hormone, Glucagon. Glucagon is going to target the liver and tell the liver to break down its Glycogen into Glucose.
Let me get my head out of the way. So we're going to have, the breakdown of Glycogen into Glucose Glycogen→Glucose. And this is going to increase your blood sugar levels. So, insulin causes the tissues to absorb glucose and turn it into glycogen. Glucagon causes the liver to break down glycogen and turn it into glucose and therefore increase the blood sugar levels. It's a nice balancing act between these two hormones. Now, I should also mention that the liver will also in response to glucagon perform something called gluconeogenesis. This is the construction of glucose Glucose, basically, from non-carbohydrate carbon sources. This is when your body is going to take, like carbon from protein, well, proteins, amino acids really, for example, take those carbons and use those to build glucose. This is a very energy-intensive process, which is why it is going to be tightly regulated, with hormonal control in the form of Glucagon. Because you don't want to just be wasting lots of energy producing glucose if, for example, you have a ton of it in your blood ready to go.
Now, if you're wondering why the liver is the only thing that's going to break down glycogen in response to glucagon. That's because the liver is going to act as a long-term store for glycogen. Muscles are very greedy. They need lots of energy and so even though insulin will cause them to store their glycogen, they're going to use that up pretty quickly. So when you have diabetes, this whole system goes awry. You can't, either produce or respond to the insulin properly. So your blood sugar levels can get out of whack and this can actually be really dangerous and if your blood sugar levels get too high, it leads to things like oscillation which is, you know, when the tissues in your body have sugars basically like chemically attached to them, this can lead to some pretty bad long-term health consequences. Conversely, low blood sugar can be much more dangerous in the short term. It can actually lead to death if it gets too low. So maintaining blood sugar levels is essential for life and you know, this really has this really nice balancing act between insulin and glucagon. You know, it's not like a static system where your body just gets it right and leaves it there. You know, your body is constantly monitoring blood sugar. And so it's going to be constantly using insulin and glucagon to sort of nudge the scales on either side to fine-tune the balance to get it to that nice, homeostatic set point. That's all I have for this video. I'll see you guys next time.
