glucose – n. 葡萄糖
insulin – n. 胰岛素
diabetes – n. 糖尿病
survive – v. 幸存，活下来
magenta – n. 品红色，洋红
scenario – n. 情节，方案
diagram – n. 图解，简图
float – v. 飘，浮动
insensitive – a. 不敏感的
desensitize – v. 使不敏感，脱敏
re-sensitize – v. 再使敏感
sensitize – v. 使敏感，致敏
uptake – v. 摄取，吸收
★Video ★
Glucose, insulin and Diabetes
★ Transcript ★
Every cell in the human body needs energy to survive and do its different functions. If we're talking about a brain cell, it needs energy to keep stimulating other brain cells and sending on signals and messages. If it's a muscle cell, it needs energy to contract. They need energy just to do the basic functions of a cell. And the place that they get that energy from, or the primary source of that energy, is from glucose. Glucose is a simple sugar. If you were to actually taste glucose, it would taste sweet. And glucose gets delivered to cells through the bloodstream. So this right here, I'm drawing some blood that's passing by a cell. Maybe the blood is going in that direction over there. And inside the blood, let me draw some small glucose molecules passing by. And so in an ideal situation, when a cell needs energy, glucose will enter the cell.
Unfortunately, it's not that simple for the great majority of cells in the human body. The glucose won't enter by itself. It needs the assistance of a hormone or a molecule called insulin. So let me label all of these.
This right here is the glucose, and it needs insulin. So let me draw insulin as these magenta molecules right over here. That over there, that is insulin. And the surface of the cells, they have insulin receptors on them. And I'm just drawing very simplified versions of them, kind of a place where these magenta circles can attach, can bind.
And what happens is, in order for the glucose to be taken up by the cell, insulin has to attach to these receptors, which unlocks the channels for glucose. In order for the glucose to go in, insulin has to bind to the insulin receptors. And then, once that happens, then the glucose can be taken up by the cell.
Now, unfortunately, things don't always work as planned. So let me draw a couple of scenarios here. So, once again, let me draw my very simple version of a cell and let me draw the bloodstream going by right over here. And then let me draw the glucose in the bloodstream. So I have my glucose floating by, and then I have my insulin receptors on the surface of a cell.
Now, the first thing that could go wrong here is what if the body does not produce insulin? Insulin is produced in the pancreas. What happens if the pancreas is not producing insulin properly?
So no insulin.
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Well, in this situation, since there's nothing to bind to these receptors, the glucose channels won't be opened up, and the glucose will not be able to enter into the cell. And this situation is type 1 diabetes, where you've got glucose. So in theory, you have energy and you have properly-functioning insulin receptors, but you just don't have insulin to unlock the gates for the glucose--for the glucose to actually go into the cell. The other scenario you could imagine happening -- let me draw the cell again.
So there is my cell and let me draw the blood flowing past the cell. And once again, obviously, this is just one of trillions of cells in the human body. We have an estimated 10 to 100 trillion cells. So this is a very simple diagram, but, hopefully, it gets the point across. So once again, let me draw some glucose floating by. Let me draw some insulin receptors on the cell.
Insulin receptor there, maybe an insulin receptor right over there. And let's say we even have some insulin. Our pancreas is producing insulin and putting it into our bloodstream. So it's there to be used. But a situation can arise where the receptors are not working properly or we become insensitive or desensitized to insulin. So in this situation--sometimes maybe it might be the insulin is hard to bind or, even if it does bind, it's not working properly. So the glucose will not enter the cell. I already wrote desensitized. So in either one of these scenarios - let's just think in a very broad level.
I'm not going to go into the details of the actual therapy for these diseases of how it can be cured. Oh, and I didn't even name the second one. The second one right here, as you can imagine, if this up here is type 1 diabetes, this down here is type 2 diabetes. The simple way that--I don't want to say that it's necessarily simple, but the way that you could manage type 1 diabetes is you can inject insulin. The only problem here--it's a big one, though, is that there's no insulin in the bloodstream. Everything else is working properly.
So over here, we can inject insulin. And then you'll have insulin to attach to the receptors, and then the glucose can be processed properly. Type 2 diabetes--there's multiple lines of attack. One thing that you can do—there are actually drugs that attempt to re-sensitize your insulin receptors. You can also do that with a combination of lifestyle changes that makes your body, I guess, more sensitized to sugar. Or you can even--if things get severe enough, you can add insulin, just like you would do in type 1 diabetes. And you can say, wait, I already have insulin here. Why would I add more insulin?
Well, remember, the cells can process insulin, but they're desensitized. They would need more insulin in order to uptake the same amount of glucose. So if you add insulin, you could possibly have enough of a trigger that the glucose can actually be taken up. But there's multiple lines of attack here, and usually the first one are giving drugs that help, hopefully, re-sensitize or make you less desensitized to the actual insulin. So the last thing I just want to think about a little bit is -- well, what happens if you didn't do this. Well, there's two major problems here. Obviously, your cells can't function if it's not taking up glucose. So your cells will have no energy.
And another problem -- if you weren't to manage either one of these types of diabetes, is that sugar, if it gets to high enough concentrations in the blood, it can actually cause a lot of damage. Sugar can cause damage to the body. So you don't want either of these things happening. You want your cells to have energy, and you don't want to have too much sugar flowing in your blood and causing damage to your body.
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★Test ★
1. Which of the following statements are true about insulin?
A. It can be taken orally or injected subcutaneously to control high glucose level in the blood
B. It is an endogenous replacement for low insulin levels in patients with diabetes mellitus
C. It acts on various insulin receptor sites to facilitate entry of glucose into the cells
D. It should be avoided in pregnant patients with diabetes 2. Which of the following regimens offers the best blood glucose control for persons with type 1 diabetes?
A. A single anti-diabetes drugs
B. Once daily insulin injections
C. A combination of oral anti-diabetic medications
D. Three or four injections per day of different types of insulin.
Answers 答案 1. C. It acts on various insulin receptor sites to facilitate entry of glucose into the cells Rationale: It is the insulin’ mechanism of action to control hyperglycemia. It is in parenteral form only and is an exogenous replacement for low insulin levels. Lastly, insulin is the treatment of choice in pregnant patients with diabetes. 2. D. Three or four injections per day of different types of insulin. Rationale: Because persons with type 1 diabetes do not produce insulin, they require insulin and cannot be treated with oral anti-diabetic drugs. Several injections of insulin per day, calibrated to respond to measured blood glucose levels, offer the best blood glucose control and may prevent or postpone the retinal, renal, and neurological complications of diabetes.
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