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2012-3-9 16:13 上传
作者: 论坛助手 时间: 2012-3-9 16:14
What does blood pressure really mean? What does it actually measure? Watch, listen, and learn as Leslie once again explains clearly and makes it so simple for everyone of us to understand easily about the principles behind this new episode.
Have fun!Transcript of Today’s Episode
Hello and welcome to another episode of Interactive-Biology TV where we’re making Biology fun! My name is Leslie Samuel, and in this episode, Episode 54, I’m going to be talking about ‘Blood Pressure and Mean Arterial Pressure.’ These are the two things I’m going to cover today. Blood pressure… You know, when you go to the doctor’s office, one of the first thing they do is they take your blood pressure. And, you know what? After today, you’re going to know exactly what they’re doing and what it means, if you don’t already know. So, let’s get right into the topic for today.
Here, we have the heart. We’ve been speaking about the heart because we’re talking about the cardiovascular system or the circulatory system and the heart has a very important job. It’s pumping the blood throughout the body. The blood carries oxygen and nutrients to the muscles and to the other organs that need this in order for you to live; in order for you to do all the things that you are doing right now.
Here is the heart. If we take the heart and we put it inside the human body, you can see here, we have the human heart and it is serving the purpose of pumping the blood through these arteries, to the rest of the body. Of course, the blood is coming back via these veins to the heart. That process goes over and over. It’s also sending the blood to the lungs so that it can get the oxygen that it needs and then send that to the body and so on. We’ve kind of spoken about that in previous episodes.
Today, we want to talk about blood pressure. First, I’m going to define blood pressure and I’m going to do it simply by writing here. Here, we have the blood and over here, we have blood vessels. As the heart is beating, and it’s sending that blood out to the body, it’s going via these blood vessels, and because it’s being pumped, that is going to exert a pressure on the blood vessels. We’re going to call this pressure a ‘hydrostatic pressure.’ The reason we call it a hydrostatic pressure is because blood is a fluid, and when fluids exert pressure on something, that is called, ‘hydrostatic pressure.’ Okay, so, the blood is being pumped. It’s going through these blood vessels. It’s hitting against the walls of the blood vessels, the inner lining of the blood vessels. That is exerting a pressure on those blood vessels. This is what we mean when we say ‘blood pressure.’
When the doctor is taking your blood pressure, or the nurse is taking your blood pressure, they are checking to see how much pressure is exerted on the blood vessels by the blood. That is a very important measure when it comes to the health of your body.
When the blood leaves the heart, as we’ve shown before, the blood then goes into the aorta which is this vessel that’s leaving from the heart, and then, that goes down here. This is also the… this is called the descending aorta and it goes via these other blood vessels to the rest of the body. It would make sense to understand that the closer you are to the heart, the more you’re going to feel that pressure. If you are right by the heart, you’re going to feel more pressure than if you are all the way down here in the toes, right? Because here is where the heart is beating, and the farther away you go from that, the lower the pressure is going to be.
Let’s look at how this works. What I’m going to do is I’m going to draw a little graph here. (I just realized that I can use a ruler on my tablet which makes sense but, I just never thought about it). Here we have the y-axis and then, here, we are going to draw the x-axis. What I’m going to do is kind of chart the blood pressure as the blood is going from the heart to the, first it’s going to go via the aorta (let me write ‘aorta’), and that’s right here. As it leaves the aorta, it’s going to go to some little smaller vessels and those are called arteries. From there, it’s going to go even smaller to the arterioles. From there, it’s going to go to the capillaries (I’m just going to write here ‘cap’). That is where it actually crosses over from being in the arteries section, arteries and arterioles, to where it’s going into the veins. But, before it goes to the veins, it’s going to go via the venules and then, the veins. When it’s in the venules and the veins, it’s because it’s going back to the heart eventually via the vena cava.
We’re going away from the heart via the aorta and then, we go to the arteries. We’re going away — a very easy way of remembering this is the ‘a’ in ‘arteries,’ ‘arterioles,’ and ‘aorta’ is going ‘away’ from the heart. When it reaches the tissues and the organs, it’s going to have an exchange in the capillaries where it then goes into the venules, to the veins, and then, back via the vena cava to the heart.
Let’s look at pressure on the y-axis. I’m going to give these some values of 20 (let me just write them in here first. Okay, it’s not fully evenly spaced), 20, 40, 60, 80, 100, 120, and 140. On the y-axis we’re dealing (I’m just going to write it over here), with pressure in millimeters of Mercury (mm Hg).
When the heart contracts, we have ventricular contraction and that’s when we’re going to get the greatest amount of pressure because the ventricles are larger than the atria. When they contract sending the blood to the rest of the body, that’s going to give you the systolic pressure, which is going to be the greatest pressure. We’re going to see here, (let me draw this in… Let’s go with red), the ventricles are contracting so the pressure is going to increase significantly and then, as the atria contract, you’re going to get that little bump there. That process continues as the heart beats, continues as the heart beats. We’re in the arteries.
As we go away from the arteries and into the arterioles, what you’re going to see, we’re getting away from the heart a little bit, the pressure is going to start kind of going down, going down. As you go away, you’re going to see smaller fluctuations. You’re not getting as great of an effect. As we reach into the capillaries, it’s kind of dying down even more and the pressure is going to continue going down and down until, on the way back to the heart, there’s hardly any pressure remaining. I mean, in comparison to up here, where we had pressures of up to 120 mm Hg, or sometimes even more in this situation, in comparison, the farther away we get from the heart and as the blood is being pushed back to the heart, we don’t get these fluctuations in pressure and there’s significantly less pressure as the blood is going back to the heart.
When the doctor takes your pressure and the doctor says, “You are in excellent health. Your blood pressure is great,” what are the numbers that you usually hear? The numbers that you usually hear are 120 over 80 (120/80). What that refers to, of course at the top, we have the systolic pressure and here we have the diastolic pressure – systolic pressure and diastolic pressure. Systolic is during systole contraction so, that’s the higher point. Diastolic is during relaxation where we have a lower point. If you have that 120/80, you are a happy camper. All is well with the world, at least where your blood pressure is concerned. That is what we want to have.
That is blood pressure. When you’re measuring blood pressure, you’re measuring the difference between systole and diastole – contraction and relaxation.
Now, let’s talk a little bit about ‘mean arterial pressure.’ (I’m just going to write M.A.P. for short). Mean arterial pressure, when you hear the word ‘mean,’ you always think average. The mean arterial pressure is basically the average pressure in the arteries. We’re not looking at the fluctuations. We are looking at the average. If we were to take the average here, I’m just going to plot a second line, it would look something like this. So, straight line here and as it goes down, it’s going to look a little like this until where we have a straight line here, it follows that straight line. That gives us the average pressure in the arteries.
There’s a formula that we use to calculate mean arterial pressure. Mean arterial pressure, M.A.P., is going to be equal to CO times PR.
M.A.P. = CO x PR
Now, two of these you know already: M.A.P., mean arterial pressure; and CO, you should know that that is cardiac output. PR is one that we haven’t covered. PR is ‘peripheral resistance.’ As I said,
M.A.P. = CO x PR
We’re going to go more into peripheral resistance in the next episode so, I’m not going to deal too much with this. The main thing that you want to know is the two factors that are going to influence mean arterial pressure is cardiac output and peripheral resistance. Peripheral resistance is basically, we’re going to define that as, opposition to blood flow. The blood is flowing but, of course there’s going to be some resistance, there’s going to be friction between the blood and the walls of the blood vessels and so forth.
There’s another way of calculating mean arterial pressure. Mean arterial pressure is also equal to diastolic blood pressure, so, that’s during diastole, relaxation, plus 1/3 times systolic blood pressure minus diastolic blood pressure (my handwriting is getting kind of sloppy there but, you get the point).
M.A.P. = diastolic BP + 1/3 (systolic BP – diastolic BP)
Once again, if you’re looking at that graph where we had something kind of looking like this, in the beginning, and if this is 80 and this is 120, the mean arterial pressure is going to be equal to 80 plus 1/3 of 120 minus 80, is 40, and that’s going to be equal to 80 plus let’s see, 1/3 of 40, let’s go with 13.3, I’m just going to leave that at 13, so, mean arterial pressure would be equal to 93 mm Hg.
M.A.P. = 80 + 1/3 (40) = 80 + 13 = 93
That’s mean arterial pressure. Two ways to calculate it: Cardiac output times peripheral resistance. We’ve dealt with cardiac output, that’s the amount of blood pumped by the heart every minute and we’re multiplying that by peripheral resistance which is the opposition to blood flow. In Episode 55, we’re going to go a little more into peripheral resistance or, we can take the diastolic blood pressure plus one-third of the difference between the systolic and diastolic blood pressures which in this case would be 80 plus a third of 40 which would be approximately 13, which gives us 93 mm Hg:
M.A.P. = 80 + 1/3 (40) = 80 + 13 = 93 mm Hg
That’s pretty much it for this episode. Of course, if you want to check out some more Biology videos and other resources like quizzes and the community that we have at Interactive-Biology, you can check out the website at Interactive-Biology.com.
That’s all for now, and I’ll see you on the next one.
作者: frog_0612 时间: 2012-3-10 17:12
:L我去
连英文解说原文都有
太多的单词不认识了
作者: hbmeihuan 时间: 2012-6-22 22:03
很好的资料，还带原文的:victory:
作者: 苍耳 时间: 2012-7-29 13:25
血压是什么意思呢？它实际上是什么衡量？看，听，和学习作为莱斯利再次解释清楚，并使得它使我们每个人要了解有关这个新的情节背后的原则很容易简单。
有乐趣！今天的集成绩单
你好和欢迎到另一个互动的生物学电视情节我们正在做的生物学乐趣！我的名字是莱斯利•塞缪尔，并在这一集，54集，我将要谈论的血压和平均动脉压。“ 今天我要说的包含两个方面。血压......你知道，当你去医生的办公室，他们做的第一件事情之一，是他们把你的血压。而且，你知道什么？今后，你将会知道他们在实际上载做什么并且为什么这么做，除非你不想知道。所以，让我们的转入今日的的主题。
在这里，我们的心。我们已经谈论的心脏，因为我们正在谈论的心血管系统或循环系统和心脏有一个非常重要的工作。它的血的血液流经整个身体。血液携带氧气并营养到肌肉和其他器官为了让您活着;为了让你做你现在正在做的任何事情。
这里是心。如果我们拿个心脏并把它放在在人体内，你可以在这里看到，我们的心脏，它正在把血液泵到这些血管里到身体的其他部位。当然，血液通过这些静脉回流到心脏。这一过程和结束。它还把血送到肺部，以便它可以得到它需要的氧气，然后传送到身体等。我们谈到了一种在以前的情节。
今天，我们想谈谈血压。首先，我要定义血压，我会做它只是写在这里。在这里，我们的血液，在这里，我们有血管。由于心脏跳动，它发送出血液到身体，它会通过这些血管，因为它被泵送，是要发挥对血管的压力。我们要调用这个压力“静水压力。” 我们把它称为静水压力的原因是因为血液是一种流体，当流体施加压力的东西，被称为“静水压力。” 好了，所以，血液被泵。它打算通过这些血管。它击中对血管，血管内壁的墙壁。这是发挥这些血管的压力。这就是我们所说的“血压。”
当医生或护士正在量你的血压，他们正在检查看血液对血管壁施加了多大的压力。这是一个非常重要的措施，涉及到你的身体健康。
当血液离开心脏，正如我们之前所说，血液进入主动脉，这是从心离开，然后，这里。这也是......这就是所谓的降主动脉，并通过这些血管到身体的其他部位。它将使意义的理解，离心脏越近感受到的压力越大。如果你是在心脏的右边，你会比一路走低在脚趾感受大压力愈大，是么？因为这里是心脏跳动的地方，离心脏越远压力越低。
让我们来看看这是如何工作的。我要做的就是在这里画一个小图。（我才意识到，我可以用对我平板的统治者，这是有道理的，但我只是从来没有想过这件事）。在这里，我们有y轴，然后，在这里，我们要绘制x轴。我要做的是一种图表血压，血液从心脏到去，首先它要通过主动脉（让我写“主动脉”），这是在这里。当离开主动脉，它将进入较小的血管称为动脉。从那里，它会去更小的动脉。然后，它会去的毛细血管（我只是写在这里的“上限”）。也就是说，它实际上从大动脉，动脉和小动脉，汇入静脉。但是在进入经脉之前，它要通过小静脉然后进入静脉。当它在小静脉和静脉，这是因为它回到心脏最终通过下腔静脉。
我们离开心脏通过主动脉然后到达动脉。我们去-记住一个非常简单的方法，这是'a'“动脉”，“小动脉”和“主动脉”，并离开心脏。当它达到的组织和器官，毛细血管交汇的地方，然后到小静脉，静脉，然后通过腔静脉到心脏。
让的在压力看在y轴。我要去给一些值20（让我只写他们先在这里好了，它不完全均匀分布），20，40，60，80，100，120和140。在y轴，我们正在处理（我要去把它写在这里），汞（毫米汞柱）毫米压力。
当心脏收缩时，我们有心室收缩，这时候我们要得到的最大的压力，因为心室比心房大。当他们收缩把血液到身体的其他部位，那将会给你的收缩压，这将是最大的压力。我们将看到，（让我这样画......还是用红色并吧），心室收缩，所以压力会显着增加，然后心房收缩，你要得到那个小凸点那里。这一进程的持续就是心脏的跳动过程。我们这会在动脉
从动脉到小动脉，你会看到什么，等我离开心脏一点点，发现压力一下降得很低。再慢慢离开心脏，你会看到小的波动并没有很大影响。当我们进入到达毛细血管，它压力将会继续下去越来越低，直到在回来的路上的心，还几乎没有任何压力。在这里，在那里我们有高达120毫米汞柱，有时甚至在这种情况下，更多的压力相比，我的意思是，相比之下，远离我们的心脏和血液正在推回心脏，我们没有得到这些波动的压力，有显着减少，血液会回流到心脏的压力。
当医生测量你的血压并跟你说，“你非常的健康。你的血压也很棒，“时，你知道你听到是什么数字吗？你经常听到的数字是（120/80）。在这之上，我们有收缩压，也有有舒张压-收缩压和舒张压。收缩压是在收缩的收缩，这就是高点。舒张压是，我们有一个较低的放松的点。如果你有120/80，你是一个快乐的人。一切都很好，与世界同步，至少在你的血压。这就是我们想要的。
这是血压。你当你测量血压，测量之间的差异收缩和舒张 - 收缩和舒张。
现在，让我们来谈谈一点点关于“平均动脉压。” （我只是去写简称MAP）。平均动脉压，当你听到这个词的意思，你总会想到“平均”。平均动脉压，基本上是在动脉内的平均压力。我们看不到波动。我们来找一个平均点。如果我们采取平均点在这里，我只是要画出第二行，它会是这个样子。所以，这里它一直下降成直线，几乎接近于一条直线。这给出了我们的动脉平均压力。
有一个公式，我们用它来 计算平均动脉压。平均动脉压MAP，是等于CO乘PR。
MAP= CO xPR
现在，这些你已经知道：（MAP），平均动脉压和CO，你应该知道，这是心输出量。PR我们还没有提到。PR是外周阻力。“ 正如我所说，
MAP= CO xPR
我们将下一章节讲述外周阻力，所以这里就先不做处理了。主要是你得知道有两个因素会影响平均动脉压，心输出量和外周阻力。外周阻力，基本来说，我们可以定义为对抗血流的力。血液流动还有一些阻力，还有的是血液和血管壁之间的摩擦等。
还有另一种方法计算平均动脉压。平均动脉压也等于舒张压，所以，这是在舒张压加上1/3倍收缩压减去舒张压（我的笔迹样马虎，但你能看到）。
MAP=舒张压+ 1/3（收缩压 - 舒张压）
再次，如果你在该图中寻找，我们有这样一种东西，在开始的时候，如果这是80，这是120，平均动脉压等于80加1/3（ 120减去80），是40，和那是去到是等于80，加上让我们来看看，1/3 40，让我们的去13.3，去掉小数，是13，因此，平均动脉压将是平等的至93毫米汞柱。
MAP= 80 + 1/3（40）= 80 + 13 = 93
这是平均动脉压。两种方法来计算的话：心输出量和外周阻力。我们已经处理了心输出量，这是血液由心脏每分钟泵的数量和我们相乘，外周阻力，这是血液流动的阻力。在章节55，我们将提到外周阻力或更多一点，我们可以采取舒张压在这种情况下，将80加上三分之一的收缩压和舒张压之间的差异，加上三分之一40这将是约13，这让我们93毫米汞柱：
地图= 80 + 1/3（40）= 80 + 13 = 93毫米汞柱
这就是这个章节。当然，如果你想看看一些更多的生物学视频和其他资源，如测验，我们在互动生物学和社会，你可以点击互动Biology.com的网站，
我们下次再见。
作者: 苍耳 时间: 2012-7-29 13:26
通过翻译并自己做了些修改，有点涩，多见谅~~~
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