Spin down your blood and find out what it's made up of. This video provides a detailed look at the composition of blood, explaining the roles of plasma, white blood cells, and red blood cells. It also discusses the process of centrifugation, the concept of hematocrit, and the conditions of anemia and polycythemia. Rishi is a pediatric infectious disease physician and works at Khan Academy. Created by Rishi Desai.
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- What percent red blood cells qualifies you as being anemic or polycythemic? What is considered a healthy range? Also, are there conditions that are characterized by fewer or greater than normal amounts of white blood cells?(54 votes)
- Polycythemia is when you have a Hb above the normal range (>18g/dl for males 16,5 g/dl for females, amount can vary a bit between different labs) or a hematocrit (percent of blood beeing red blood cells) above roughly 50% for males, and roughly 47% for females.
Anemia is when the Hb is too low, 13g/dl for males, 12g/dl for females.
Normal ranges for hematokrit varies with age, and in adult males ranges between 40-50%, and in adult females between 35-46% (amount might vary slightly between labs).
You can see a greater amount of white blood cells if you for example have an infection, or leukemia, and leukemia can also give fewer whites. Hope this helps.(75 votes)
- I heard somewhere that blood was a different color when it is not exposed to oxygen. Is this true?(27 votes)
- Not really.Oxygenated blood is bright red(due to the oxygen in it),and deoxygenated blood's a darker shade of red. Hope that answers your question. ;)(48 votes)
- How dangerous is it to be anemic or polycythemic?(21 votes)
- Polycythemia develops slowly in most cases, but can increase the cause of heart attack or stroke due to the amount of bone marrow produces. Anemia can cause fainting if not treated. Anemia can also be caused by iron deficiency.(24 votes)
- Is blood doping an artificial way to give polycythemia? Is this what Lance Armstrong did to increase his performance level?(24 votes)
- Yes. Blood doping gives you polycythemia. Blood doping can either be done through giving a healthy person a blood transfusion or by injecting them with erythropoietin, which is a hormone that causes you to produce more red blood cells.(24 votes)
- When donating blood, one of the options is to donate 'double red'. Is there and advantage do doing this? When doing medical procedures, when would give a patient plasma versus whole blood?(14 votes)
- If a double red is given, 2 bags of RBCs are given with no plasma or platelets or WBCs in them(they have a machine that filters the other products back into you.) It is good to give that if you are O- because they CAN use them in an emergency situation. The above post about plasma is VERY VERY wrong. Plasma is what carries the antibodies that actually do all the damage in a transfusion reaction. EX. if a person is A blood type, they have B antibody in the plasma. If that plasma is given to a person with B or AB blood, the antibodies will lyse the cells causing a hemolytic transfusion reaction. Plasma is given for coagulation deficiencies because they carry clotting factors used by the body to create clots when damaged. It IS also used in emergency situations to treat shock but the blood types DO need to match. When they cross match compatible blood and compatible plasma, they give it in a 1:1 ratio. When you give one bag, you are giving Whole blood so they separate all of the components(RBCs, Plasma and platelets) so it can be used in three different ways. The plasma can also be processed into cryoprecipitate which is only used for coagulation deficiencies.(19 votes)
- Are there lipids(fat) in blood? And what about cholesterol?(9 votes)
- Lipids and cholesterol are nutrients, and are found in blood, seeing as this is their primary method of transport.(14 votes)
- If blood contains iron and magnets attract iron why don't magnets attract us?(10 votes)
- Today, we have an effective artificial alternative of blood ? ( sorry for my English =) )(6 votes)
- What does a person have to do in order to get Polycythemia or Anemia? Is it caused because of how high or low their blood pressure is? Or is it because of their blood pressure?(6 votes)
- Anemia can come from a bad diet (lack of B12, iron and folate), bleeding (menstruation for females is a common cause), leukemia and more.
Polycythemia only meaning high amount of red blood cells, can be caused by several conditions. For example pathological conditions where the bone marrow produce an excess of RBC, or a state of hypoxia (lack of oxygen) caused by for example heart or lung disease where the body compensate by producing more RBC to carry the oxygen.(7 votes)
- Do white blood cells carry oxygen? (do they need oxygen)(5 votes)
- White blood cells don't transport oxygen to other cells and cell tissues like red blood cells do. But, they do need oxygen to make the energy the cell will use. There is a video on this site about cellular respiration you can watch to see how cells use oxygen and glucose to make energy.(11 votes)
Let's say that I go to the doctor's office, and I hate when this happens, but I, once in a while, have to have my blood drawn. And the reason I hate it is that I'm kind of a chicken when it comes to getting my blood drawn. I don't like needles. But of course, I do as I'm told, and I get my blood drawn. I just try to distract myself when the blood is actually filling that needle. And I usually look away, and before I know it, it's done, right? So it's out of my mind, and I walk out of the office pretty happy, because now I don't have to think about it anymore. But here's what I want to do now is kind of follow the path that this blood takes and think about what happens next, after they draw the blood. So the first step is they usually put that blood into a tube. And usually that's done directly, actually. These days, usually that tube is already kind of sitting and waiting, and it's collecting blood immediately. So this is my cap for my tube. And inside my tube, I've got blood. This is my blood filling up this tube. And this is kind of a special tube. And the thing to know about this tube is that on the walls of the tube is a chemical that basically prevents the blood from clotting. You don't want the blood to clot, because it's hard to do any sort of lab work on it. And so this tube is very special in that way. It won't actually clot. And so to make sure it's working properly, sometimes people kind of gently shake the tube up a little bit, just to make sure that there's good mixing and so that the blood doesn't clot. Now from there, the blood goes over to the lab. So there's a machine in the lab that takes blood from me. This is my blood. But it also takes blood from other people, let's say a few other patients in the hospital that day, or in the clinic. And all of our blood is kind of labeled and put into this machine. And what the machine does is it spins. It basically spins really quickly. So all these tubes, they're attached so they don't fly away. But they basically spin as well. And if all these tubes are spinning, then what it creates is a force called the centrifugal force. So this process is called centrifugation. Let me write it out here. Centrifugation. And the machine is called a centrifuge. So it's basically going to spin really quickly, let's say, in one direction or the other. And as a result, what happens is that the blood starts separating out. And the heavy parts of blood kind of go to the tip of the tube. And the less dense part of blood actually rises towards the lid. So after you've centrifuged-- let's say you've actually gone through this process, and you centrifuge the blood. Now you have the same tube, but I'm going to show you kind of an after picture. So let's say this was before I actually spun the tube, and now I've got an after. This is my after picture. So after I spin the tube, what does it look like? Let me draw the tube. And the biggest key difference here is that instead of having one similar looking homogeneous liquid, like we had before, now it actually starts looking really different. You've got three different layers, in fact. I'm going to draw all three layers for you. So this is the first layer. And this is the most impressive layer. The largest volume of our blood is going to be in this top layer. So remember, this is the least dense, right? It's not very dense, and that's why it stayed near the lid. And it's actually going to make up about 55% of our total volume. And we call it plasma. So if you've ever heard that word plasma, now you know what it means. So if I was to take a drop of this stuff-- let's say I took a little drop of this plasma, and I wanted to take a good hard look at what was in my drop-- 90% of plasma is going to be nothing more than water. So that's interesting, right, because the major part of blood is plasma, and the major part of plasma is water. So now you're seeing why it is that we always say, well, make sure you drink a lot of water. Make sure you're hydrated. Because a big part of your blood itself is water. And in fact, that's true for the rest of your body as well. But I want to stress that it's true for blood as well. So that leaves the rest, right? We've got 90%, we have to get to 100%. So what is 8% of this plasma made up of? It's protein. And let me give you some examples of this protein. So one would be, for example, albumin. And albumin, if you're not familiar with it, it's an important protein in your plasma that keeps the liquid from kind of leaking away out of the blood vessels. Another important protein, the antibody. And this, I'm sure you've heard of, but antibodies are basically involved in your immune system, making sure that you stay nice and healthy and don't get sick with infections. And another part of the protein, another type of protein, to kind of keep in mind, would be fibrinogen. And this is one important protein involved in clotting. And there are actually many other clotting factors, we call them, as well. So I'm just going to put clotting factors here. So these are proteins. Things like albumin, antibody, fibrinogen, these are all proteins. Now we've still got 2% to account for. And this is going to be things like hormones, for example. And that could be something like insulin. We've got electrolytes. That could be something like sodium. And we've got, also, nutrients. So nutrients, that could be something, for example, like glucose. So these things all make up your plasma. So a lot of the things that we kind of think about, talk about, are all in your plasma. including vitamins and things like that. So now another layer we have right below the plasma, is here in white. And if I was to kind of zoom in on it, it would be a very, very tiny part of blood-- less than 1%. And this is actually white blood cells. This layer contains white blood cells and platelets. So these are cellular parts of our blood. And they make up a very tiny bit, but they're a very important part of our blood, of course. Below this layer, so now the most dense layer of blood, would be the red blood cells. So this is this last bit. And this, just to make it add up, would be about 45%. And these red blood cells, of course, contain within them hemoglobin. So sometimes it gets tricky because you forget, you think, oh, protein, so that must be plasma. Remember, red blood cells and white blood cells, within them, they have proteins as well. So just remember, they contain lots of protein as well, within them. So, for example, hemoglobin. So this is an example, right? Now one word you may have heard of is serum. So what is serum, exactly? Well, serum, this word, is very, very similar to plasma in terms of what it's made of. In fact, if I was to circle what is in serum, I would circle this bit. Basically everything within my blue line would be circled. This is serum. And so the only thing I've left out of serum is fibrinogen and the clotting factors. So plasma and serum you can just remember being very similar. And the exception is that the serum does not include the fibrinogen and clotting factors. Now, looking down at the red blood cells, what can we learn from that? Well, you may have heard this term hematocrit. And if this was my blood, if I actually had drawn my blood, as I drew in this picture, and this was my blood, my hematocrit would have been 45%. And all that means is hematocrit equals volume taken up by red blood cells divided by the total volume. So if, in this case, my total volume is 100, my percent, I already told you, is 45%. So that's why I knew my hematocrit was 45%. It's just the percent taken up by your red blood cells. And that's an important percent to know, because the red blood cells are the part of blood that are actually carrying the oxygen around. Now to kind of stress this point of hematocrit further and maybe even kind of introduce a couple of new words, let me draw out three little vials of blood. So let's say I have three vials here-- one, two, three. And these are going to be three different people, let's say. But they're all very similar, same age, same gender. Because hematocrit, what is normal, is actually going to change depending on whether you're talking about a certain age, a certain gender, even depending on where you live in terms of altitude. Because let's say you live at the top of a mountain, that is going to affect your hematocrit as well. So a lot of things affect hematocrit. But let's say we have three people kind of very similar in those ways. Now the first person, I'm going to draw out their blood here. Their plasma, let's say, is taking up this much of their total volume. The second person, their plasma is taking up this much of their total volume. And the third person, their plasma is taking up, let's say, a lot, of their total volume. Let's say all the way down to here. So you spun all three, and this is what you've gotten. Of course, all three still have white blood cells. Got to draw that in. And they have platelets, of course, that's this tiny little layer-- less than 1%, we said. And the remainder then has to be red blood cells. So this is the red blood cell layer right here. This is the red blood cell layer. And it's really large here for this second individual. And this third individual, it's actually kind of on the smaller side. Not too much of the volume is taken up by red blood cells. So here, if I was to kind of go through and label these folks, I would say, well, this first person is what I would call normal. The second person has a lot of red blood cells. It's so, so predominant. This is a very high percentage, right? I know this is taking up a high amount of the total volume. So this person has what I would call polycythemia. It's just a medical word to say that the volume of red blood cells over the total volume is very high. Or you could say their hematocrit is very high. And this person, this third person, has a very low amount of red blood cell volume relative to the total volume. This is actually pretty low. And so this person, I would say, has anemia. So if you've ever heard these terms anemia, or I'm anemic, sometimes people say, or even the word polycythemia, now you know it's just referring to what volume of their blood is taken up by red blood cells.