Module 3 Week 4.docx

Module 3 Week 4.docx - Module 3 Week 4 Hyperglycemia vs...

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Module 3 Week 4 Hyperglycemia vs. Hypoglycemia So we have this intricate insulin system, insulin receptor system, to drive the glucose down. However, we don't want to drive the glucose down too low. If we drove it all the way down, it's usually around 80 milligrams percent, if we drive it down to about 20, I guarantee you're going to be flat on your back, fainting, because neural function, brain function would stop acting. So we want to keep that glucose up, in spite of the fact that insulin is driving it down. So we have a particular mechanism that, going back to the pancreas, going back to the Islets of Langerhans, that's where those beta cells exist. They will produce, in another set of cells called the alpha cells, they will release a substance called glucagon. So these alpha cells now, like the beta cells, are sensing the amount of glucose that's being circulated through the body. And when blood glucose starts to get low, somewhere around 60, 50 milligrams percent, they will start producing glucagon. Glucagon will circulate through the body, it will go back to the liver. And what it does in the liver is release the stash of glycogen that we stored. Remember, after we ate, we had this massive surge of glucose in the liver and we stored much of this glucose in the liver as glycogen, a storage form of glucose. What glucagon will do is release the glycogen. When we release it, it turns back to glucose. it's called glycogenolysis , the breakdown of glycogen. And that glycogen turns into glucose. So, where insulin is going down, the glucose is going down because the surge of insulin, the release of glucose from glycogen will start to increase it again. So we won't constantly go down low. Now, in addition to glucagon being released in this drop of glucose, we also have another hormone that is manufactured in another set of cells in the Islets of Langerhans. These are the delta cells. So they're different. They release another hormone called somatostatin. And what somatostatin does is very little active things by itself. But what it will do is damp down both the alpha and the beta cells, as well its reactions in various receptors of the body. And by doing that, we prevent the glucose from constantly going up and down. If we had no somatostatin, what will happen is the insulin will drive the glucose down. The glucagon will drive it back up, which will stimulate insulin, and we'll forever be in this cyclic state. So what the somatostatin does is neutralizes state, stop the swings, and allow us to have a rather stable blood glucose level. First Defense of Hypoglycemia So now we have a system that is operated to keep our glucose up, and what we have to do is dip into our stash of glycogen. But we can maintain blood glucose for at least a couple hours because that's the amount we have in the liver that's going to keep the blood glucose up. But suppose you decided you didn't want to eat. You don't have time. You have an exam. You have other things to do. What happens then to this glucose? You only have a limited supply of glycogen. You run out of this defense of glucose. Well, then you've
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