Transcription
Hello everybody. I am Deepika from LearnOHub, a free learning platform where you can study Physics, Chemistry, Maths, Biology, absolutely for free, only at learnohub.com. So students, today is the time to discuss the remaining topics from the chapter, the circulatory system. So I hope the first part of the video was clear to you. So let us now focus on the remaining parts of the chapter. So let's get started.
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So starting today's session with blood transfusion and blood groups. So, blood transfusion. So we know that blood is very, very important for everyone, right? So it has certain important cells. It plays a very important role in circulating the substances. It helps us in giving us the immunity, right? So, but in certain cases, when the person has less amount of blood, so you must have, you must have read "Holdings" while on the road, "Donate Blood", but not on the road, right? And there are certain NGOs also which, uh, which are really, which actually, uh, ask people to donate blood, so that that blood can be given to the needy person, right? So when the person is injected with the blood due to some reasons, he has certain less blood in the body, there is some surgical procedure due to which the person has lost a lot amount of blood. So in that case, when the blood is given to a patient, so that is called as blood transfusion. And how is this blood transfusion done? So, blood is basically taken from a healthy person, and that healthy person is called as a donor, right? And the blood is introduced into the patient's vein. So this is how the blood transfusion is done. This is just the basic step that is done for a blood transfusion.
So now, the type of blood transfused. What type of blood will you transfuse? What type of blood will that person need? So that depends on the blood groups. So any blood group cannot be transfused to any person, right? So there are different types of blood groups, and there is a specific type of blood group that matches. There are specific type of blood group that matches with each other, right? So the type of blood transfused should match the blood type of the recipient, okay? So we will discuss about this concept, which blood group can be transfused, right? Okay.
So the whole concept of this blood grouping, this blood grouping is a very, very important concept in medical science now, where in certain cases, when a person has less blood, so that person needs to, I mean, the doctors need to transfuse blood into the patient. So this whole concept was introduced by Carl Landsteiner. So Carl Landsteiner introduced this concept, and he only told us that humans are BCS. So these are the RBCs, right? So they are enucleated, as we all know. So these RBCs have a certain type of antigen on its surface, okay? So there are basically two types of antigen, antigen A and antigen B. So these are, they have the specific type of proteins on their surface, and we call those proteins as antigens. So this might have A, so these are the, um, bloods of different RBCs of different patients, right? So this might have B, right? And this might have none of them, right? So there are no specific proteins called antigens present on the surface of the antibody, surface of the RBCs of this particular individual, right? So these antigens play a very important role in blood transfusion. So let's see how.
So now, uh, we have studied that the RBCs of the patients has certain type of special proteins that is present on the surface of the RBCs, and they are of two types. One is antigen A, and another is antigen B. Now, in the plasma of their blood, they have the complementary antibodies, which mean if they have antigen on the surface of their RBCs, so the plasma of blood contains complementary proteins, right? And these are called as antibodies. These complementary proteins, which are present in the plasma of the blood, are called as antibodies, okay? So depending on all the presence of antigen and antibody, there are four types of blood groups. So the blood groups are A, B, AB, and O. So what will be the antigen on the surface of the RBCs having blood group A? So antigen is going to be A, and the antibody is going to be B. So as there are two types of antigens, antigen A and antigen B, so there are two types of antibodies, antibody A and antibody B. So a person having antigen A on the surface of its RBCs, right? So in the blood plasma, that person will have complementary antibodies, which mean the antibody will be B. So for patient having, for an individual having blood group B, so the antigen on the surface will be B, and the antibody in the plasma will be antibody A, okay? Now talking about the blood group AB, so it means that that particular individual has both the type of antigens on its, on the surface of their RBCs. So that individual will have A as well as B antigen. Talking about the antibodies in plasma, so if we talk about the antibodies in that case, this person will not have any antibodies. Now coming on to the next blood group, that is blood group O. So in case of blood group O, there are no antigens on the surface of RBCs, but their blood plasma do have antibodies. And what antibodies will that person's blood have? So both the types of antibodies, antibody A as well as antibody B, okay? So I hope this much is clear to everyone.
Now, if we come to blood grouping, right? So if we come to blood groups, there are various types of blood grouping systems, but the two major types are blood group system and Rh system, right? So these are the two types of blood grouping systems, okay? So in this particular case, we are going to just talk about two of them, and we will not extend our discussion to other types of blood group systems. So in ABO system, we have four types of blood groups. So just go around in your class and ask what are the different blood groups in, in your class, right? So some of them will say A, some of them will say B, some of them will say AB, or some of them will say O, right? So there is no, no other blood group, okay? So just think about your blood group and try to think what antigen is present on the surface of the antibodies, uh, sorry, or on the surface of the RBCs of your blood. So your, if you have blood group A, so this means the antigen on the surface of RBC will be antigen A, right? If you have blood group B, then there will be antigen B, right? And what will be the antibody? So that will be the complementary. If A is the antigen, then antibody will be the B, okay? So, and now there are different types of transfusions that are possible. The one simple transfusion that happens is the similar type of blood group. So if the, if there is a donor and there is a recipient, okay? So if donor has, if recipient has A blood group, A, so simply that can receive from A, that can receive blood from a donor who has the same blood group, that is the blood group A, okay?
Now, I, but it is not possible in all the cases, okay? So that we will discuss. So first of all, we have blood group O and AB, okay? So since there is no antigen present on the surface of the RBCs of a person having blood group O, okay? So in those cases, a person having blood group O serves as a universal donor, which means a person having blood group O can give, can donate blood to an individual having blood group A, as well as B, as well as AB, right? So all of them can receive blood from an individual having blood group O. So this means this individual will be a universal donor. On the other hand, let's talk about AB. So if we talk about blood group AB, so that individual has both the antigens on its surface, right? But there are no antibodies in the blood plasma. So this means this person can receive blood from all the blood groups, from O, A, AB, and B, for all of them, okay? So in, let us now talk about what are the different combinations of blood grouping and which blood group can receive blood from which type of individual.
Now, the summary of blood group matching. So matching and mismatching in this blood group system, okay? So we have the blood group donors and we have the blood group recipients, okay? The first thing that we know is AB is the universal recipient, right? So this is the universal recipient, and O is the universal donor, correct? So this means this person can, a person having blood group AB can receive blood from all the blood groups, okay? And a person having blood group O can donate blood to all the blood groups. One thing very clear. The second thing that we know is a blood group A donor having blood group A can donate blood to a recipient with blood group A, okay? So same in the same blood group, the blood can be donated. So in all these cases, blood can be given. Now, when a person has blood group A, so on the surface of their RBCs, they have antigen A, and in the plasma, they have antibody B. So this means if we try to give this, if we try that a person having blood group B should be given A blood group A, so what will happen? The antibodies which are present in over here, so this person will have antibody A, right? And what we are giving? We are giving blood group A, so this means this person has antigen A, right? So this blood will be rejected by this person's body, okay? So we cannot transfuse blood in this case.
Now, when the recipient is, is O. So in case of O, this person has none of the antigens, but this person has antibody A as well as B. So in this case, when the donor is having blood group A, so in this particular case, this has antigen A. So in this case also, since the antibody A is present, so this blood will be rejected by this recipient, so this blood cannot be transfused, okay? Now coming on to a blood group when the donor is B. Now when donor is B, this has antigen B on the surface, okay? And the donor A has what antigen, what, um, antibodies? So this has antibody B. So in that case, the antigen and antibody are matching, which means antibody will kill this antigen, and this blood will be rejected, right? Now talking about O, O. So again, since there is antibody B present over here, so this will also get rejected. Now coming on to AB. So AB is universal recipient, not a donor, okay? So in this case, it has antigen A and antigen B. And now a person having blood group A has antibody A. So this blood group will be rejected. And again, this person will have antigen A on its surface, on the surface, sorry, in plasma. So this blood will also get rejected. Now, in case of O, so in case of O, so there is antibody A and B, and there is antigen A and B. So in this case also, the blood will be rejected. So this means only the universal recipient can, can get blood from, can accept blood from all the blood types, and universal donor can give blood group to all the blood types. And the second thing that a person, people having the similar blood groups can donate blood to each other, okay? So I hope this summary of blood grouping is clear to everyone.
Now, the second type of system that we are going to talk about in this particular case is Rh system. So this is also a blood group system, um, where there is another antigen that is present in the blood, okay? So the blood of most people contains a substance which is called as Rh factor. So RH stands for Rhesus, which was first discovered in a common monkey. So there are two types, one is Rh positive and another is Rh negative. So in the case of Rh positive, there is an antigen D which is present on the surface of RBCs, and in the case of Rh negative, this antigen D is absent, okay? So this is how we have differentiated between these two. When a D antigen is present on the surface of the RBCs, this means that person is Rh positive, and when this antigen is lacking, when this D antigen is lacking, so in this case, the antigen RH, sorry, the antigen D, when it is lacking, so it is called as Rh negative.
So if we give, if we transfuse blood from a person having who is Rh positive, right? So Rh positive person, if it donates blood to Rh negative person, so in case of first transfusion, so within two weeks, this person will develop antibody against this factor, okay? So if in case we try to transfuse the blood again from this Rh positive patient, so what will happen? So there are antibodies which are already present in Rh negative individual now. So these antibodies will actually fight against the antigen, fight against this blood group, and which might even lead to the death of the individual. So this is also a very important thing that one must keep in mind so as to have the knowledge of blood transfusion. So every blood, every a blood, every person having blood group A cannot donate to a person having the other person having blood group A. We have the second thing that we need to check is the RH system, whether the person is Rh positive or the person is Rh negative, right? The Rh factor is very, very important in pregnancy also. So you must have seen that whenever the blood group, your blood group gets tested, so in that case, A, B, AB, or O, whatever is the blood group, so, uh, the another thing that is mentioned in it is plus or minus, right? So whether the person is Rh positive or the person is Rh negative.
So in case of pregnancy, if a woman is Rh negative, so if a woman has a blood group A negative, B negative, AB negative, yeah, O negative, okay? So in that case, if she and the husband is Rh positive, right? So the mother is Rh negative, and the father is Rh positive. So in this case, if she conceives a child who has a blood group and that is Rh positive, so in first case, the child is going to be normal. So child is going to be delivered normally. There will be no problem in the child. But now, during delivery, the body of this mother might get sensitized by these Rh positive antigens, right? So in this case, this mother will develop antibodies against this Rh factor. Okay? So now, when the antibodies are developed, and the female conceives again, the mother gets pregnant again, and if the baby is again Rh positive, so then it creates a problem. Then these antibodies will actually fight against that blood, and in this case, there are chances, there are like the chances are very high that that particular fetus will get aborted or that particular fetus might, might die in the womb only, okay? Why? Because the mother has already developed antibodies against that D antigen. When there are antibodies against that D antigen, the body will not develop, will not support a child with Rh positive blood group, okay? So in this, this case, now the medical science has developed so much. So whenever a female, female give birth to a child, so in that case, if a mother is Rh negative, so the blood group of the child is tested, right? So if the child is negative, then it is okay. But if the child is, the first child is positive, that particular female is injected with, is given some injection for, so that the antibodies do not develop against this D antigen, okay? So I hope this is also clear. The Rh is, this Rh factor is very, very important in pregnancy.
Now, coming on to the blood circulatory system. So blood circulatory system is composed of three things: one is heart, blood, and blood vessels. So blood vessels are of three types: arteries, veins, and capillaries. So let us now discuss the important parts of the blood circulatory system. Heart. So heart is located in the center of our lungs, right? So it, it seems to be on the left side, but it is actually not. So it is present in the center of the two lungs, above the diaphragm. Now, it has a narrow, triangular shaped, triangular shape that is pointed towards the limbs. So basically, heart is not on the left side, but the lower triangular portion of the heart is, is pointed towards the left side. So we feel that the heart is on the left side, but it is actually in the center of the two lungs. And when the heart contracts, the contraction is very powerful at that pointed and the triangular end of this heart. So that is why it feels like the heart is on the left side, but it is actually not. This size, if we talk about the size of the heart, often, um, adult human, so the size is about the size of the closed fist. If you, if you close your fist like this, right? So this is basically the size of your heart, which is 12 centimeters in length and 9 centimeters in width. Covering. So the heart is a very, very delicate organ, and it is protected by double-walled membrane covering, which is called as pericardium. So there is a double-walled membrane covering, which is called as pericardium, and it contains lubricating fluid, which is pericardial fluid, which reduces the friction during the heartbeat. So now, because heart has to pump throughout the day, 24/7, without stopping for a minute, right? So in this case, there could be a friction between the different parts of the heart. So for to reduce that friction, there is pericardial fluid, which is present and which reduces the friction during the heartbeat, and it protects the heart from any mechanical injury.
Talking about the chambers of the heart. So there are basically the four chambers that are present in the heart. So if I draw it like this, okay? So the upper two chambers, they are called Atria, right? So this is Atrium, and the lower chambers are called as ventricles. So what, what are they called as? They are called as ventricles, okay? So upper are called Atria, and lower are called as ventricles. So total, there are four chambers in our heart. Now, talking about the four chambers of the heart, so we will talk about their structure and their functions. So I, I am again drawing a very, very simple diagram. I do not want to confuse you at all, right? So I'm marking it as left atrium, left ventricle, right atrium, and right ventricle. So when we study the structure of these Atria and ventricles, we find out that we found that, uh, the Atria or the oracles, they have very thin walls, not very thin walls, but they have thin walls as compared to the ventricles. So the, why? Because their major function is to receive blood. They, their function is just to receive. So left, if we talk about the left oracle, so there are lungs which are present in our body, and say, these are the different body parts, right? So the function of left atrium is to receive oxygenated blood from lungs. So the blood, when it gets oxygenated, it comes from lungs to the left side of the heart, and which, which part of the left side? So of course, on the, to, on the upper chamber, right? What is the upper chamber? So that is left atrium. And from left atrium, it goes into left ventricle, right? From left ventricle, this blood, this blood is oxygenated blood, right? So it is sent to the different body parts.
Now, if we talk about the function of, uh, right Atria or right oracle, so this particular side of the heart, this particular chamber of the heart receives blood from the different body parts. So here also the blood is oxygenated. Now, this oxygen is used by the different body parts, and now this, because this blood has become deoxygenated, or you can say carbon dioxide rich blood, so this carbon dioxide rich blood goes into right atrium, and from right atrium, it goes into right ventricle, okay? So again, right ventricle will receive the deoxygenated blood from the right ventricle, this blood is sent to the lungs for oxygenation, because this was carbon dioxide rich blood, and now in the alveoli, this carbon dioxide will be given to the alveoli, and in turn, oxygen will be taken from the alveoli, right? And now the blood will again become oxygenated. So if you see over here, what is the function of these Atria? The, the function of the Atria is to receive blood from different body parts. Left side will receive blood from lungs, and right side will receive blood from different body parts, okay? But when the blood goes into the ventricles from ventricles, this blood is sent to different parts of the body. So in that case, the blood has to be pumped with a very high speed, with a very, very high pressure, so that this blood can reach the different parts of the body, correct? So that is why the walls of the ventricles, they are thick, they have thick muscular walls, which pump blood to the long distances, okay? So I hope this is clear.
Now, talking about the different blood vessels that are entering the heart, okay? So as you can see, the blood is entering also, and blood is coming out also from the heart, right? So let us first talk about the blood vessels which are entering the heart. So where does these blood vessels enter? So it will enter from the, in the chambers where the blood will enter, right? So it will, they will enter on the upper part of the heart, that is the right atrium and the left atrium, right? So first of all, let us talk about right atrium. So it receives two large vessels, one is anterior vena cava and another is called as posterior vena cava. So this is superior or anterior vena cava, and this is inferior or posterior vena cava, clear? So now, what are the functions? So anterior vena cava or the superior vena cava, correct? We also call it as pre-caval. So this is, this is located on the upper side of the heart. So this means this receives blood from the upper parts of the body, because the right side, this is the right side of the blood, and it receives all the deoxygenated blood. So right side is related to deoxygenated blood. So this means this side will receive blood from different body parts. So the superior vena cava or the anterior vena cava will receive blood from the upper parts of the body, for example, head, chest, and arms. Talking about the second type, that is posterior vena cava or inferior vena cava or post-caval, right? So this is the posterior or inferior vena cava, the one which is located towards the lower side, okay? So it receives blood from the lower parts of the body, including abdomen and legs. So the blood from abdomen, from legs, and other lower parts of the body, it is received by whom? By inferior vena cava, and it is thrown into the right atrium of the heart, okay? So these are the two main blood vessels which are entering into the right side of the heart, right atrium, right? So I hope this is clear.
Now, the second part, second chamber of the heart which receives blood is the left atrium. So left atrium receives blood from four pulmonary veins, right? So these pulmonary veins, from where do they come? They come from the lungs. Wherever the word is pulmonary, so it is related to lungs. So this means these veins, they are coming from lungs, and the blood which comes from lungs is always oxygenated blood, okay? So now, two from each lung, so two pulmonary veins from each lung are bringing the blood, the oxygenated blood into the right, our left side of the heart. So left side of the heart receives oxygenated blood from lungs and delivers also the oxygenated blood, okay? So I hope this is clear.
Now let us talk about those blood vessels which are leaving the heart. So from where do they arise? They arise from the lower chambers of the heart, that is from the ventricles, the right ventricle and the left ventricle. So the very first blood vessel leaving the heart is pulmonary artery. So it arises from the right side, right ventricle. Now, the word is pulmonary, so this means this is related to lungs. So the right side, so because the right side of the heart is, this is the right side of the heart, and it gets deoxygenated blood, right? So this deoxygenated blood is received from different parts of the body by the right oracle, from right oracle, it comes down to the right ventricle, and from right ventricle, this blood is sent to lungs for oxygenation. So which blood vessel will take this? The pulmonary artery will take this blood from right ventricle and carries deoxygenated blood to lungs for oxygenation. So this is the function of pulmonary artery.
The second is aorta, right? So aorta arises from left ventricle, from left ventricle. So left side of the heart is the side where the heart has oxygenated blood. So aorta from the left side of the heart, from the left ventricle, carries the oxygenated blood, and it supplies to all the parts of the body, clear? So which, which blood vessel carries oxygenated blood from left ventricle to different parts of the body? So that is aorta.
So next comes the coronary arteries. So coronary arteries, they, there are two, one is left and one is right, which arise from the base of aorta. Now, what, what is the function of these coronary arteries? So they supply blood to the heart muscle. So heart also needs oxygen, right? It also needs energy, it also needs to give out, uh, carbon dioxide. So there are different set of arteries which give, which supply blood to the heart muscles, and they are the coronary arteries, okay? So these, you can see over here, so this is the left coronary artery, and this is the right coronary artery, which supplies blood to the heart muscle. Whenever there is any blockage to these coronary arteries or any of their branches, it leads to the deadening of that corresponding area where that artery is not working or that artery is blocked, right? So that leads, that leads to the, deadening of those heart muscles, which actually leads to, uh, the non-functioning of that particular portion of the heart, so which is called as myocardial infarction. In in simple terms, it is called as heart attack, right? So when the heart muscles are not working properly, it only leads to heart attack.
Now, as arteries are supplying blood to the coronary arteries are supplying blood to the heart muscles, so there are coronary veins which are collecting blood from these heart walls and they are pouring them back into the right oracle, from where the, because the right portion of the heart receives deoxygenated blood, and this deoxygenated blood will be moved to the right ventricle, and from right ventricle, it will be given to the lungs for oxygenation, it will be sent to the lungs for oxygenation. The another term which is very important over here is angina pectoris, which is, which tells us about the chest pain, which is due to the insufficient supply of blood to the heart muscle. So whenever there is insufficient supply of blood to, to our heart muscles, so it, it leads to a chest pain. So the person's chest, it starts paining, and that situation is called as angina pectoris.
Now, talking about the heart wall. So there are four walls which are present in our heart. The first one is right atrioventricular wall. So as the name suggests, this is the wall which is present on the right side of the heart, between the, this atrium and ventricle. So this particular wall is called as tricuspid valve, as it has three thin, triangular leaf-like flaps. So do you, do you see these leaf-like flaps? So this is the reason why we call it as a tricuspid wall. So there are three cusps, which, which give, which has given its name tricuspid, okay? So now, these three cusps are held in position by certain muscles. So there is, you can see over here, these are certain papillary muscles, which are arising from the ventricle. So these, these ventricle, these muscles, they help to keep these flaps in position. The apex of these flaps, they are held in position by, uh, chordae tendineae, right? So these are the tendinous cords, which are called as chordae tendineae, which arise from the muscular projections of these papillary muscles. So from these muscular projections, from these papillary muscles, chordae tendineae arises, which keeps all the three flaps of the tricuspid valve in position.
The second type of wall that is present is left atrioventricular wall. So as the name suggests, it is present on the left side, between the Atria and the ventricle, okay? So left side of our heart receives oxygenated blood. So in a similar way, it is located on the left side, and it has two cusps. So that is why it is called as a bicuspid, or it is also called as a mitral wall, right? So do you see? So there are two cusps that can be seen over here. So these are the two cusps, right? So due to these two cusps, this is called as bicuspid, or it is called as mitral wall. So this is present on the left side of the heart. Tricuspid is present on the right side, and bicuspid is present on the left side of the heart.
Now, the third type of wall is pulmonary semilunar wall. So it is located at the opening of the right ventricle into the pulmonary artery. So right side of the heart receives deoxygenated blood, and from right ventricle, there is a pulmonary artery, which carries blood away from the heart towards the lungs, right? So towards the lungs for oxygenation. So at the, at the, you can say, at the opening of this pulmonary artery, there is a valve located, which is called as pulmonary semilunar wall. So it is a pocket-shaped wall, and they are three in number.
Now, just think, where do, where else do we need these walls in our heart? So talking about more walls in the heart, so their fourth type of a wall, which is called as aortic semilunar wall. So the very first thing, it is somewhere or the other present at the aorta, clear? And aorta also, now aorta, it takes blood away from left ventricle to the different parts of the body. It takes oxygenated blood, right? So basically, it is present, it is located at the point of origin of aorta from left ventricle. Again, it is pocket-shaped, and they are three in number. So I hope all the walls that we have studied are clear to you. So the first wall, sorry, the first wall that we studied was a tricuspid valve. So tricuspid valve, which is present on the right side of the heart, between, um, Atria and a ventricle. Second was the bicuspid wall, which is present on the left side of the heart, between Atria and ventricle. The third type of valve is present at the origin of, at the end of, basically, at the end of right ventricle, and we call it as a semilunar wall, right? So pulmonary semilunar wall. And the last, uh, type of a wall is the fourth type of wall, that is aortic semilunar wall, which is present at the beginning of aorta. So it is at the beginning of aorta, and nearer to the end of left ventricle, clear? So I hope all of them are clear to you.
Now, the circulation of blood into the heart. So how does this blood get circulated in the heart? So there are two chambers, upper and the lower chambers, right? And there are certain blood vessels associated. Now, say the blood is already there in the heart. So the blood is there in the upper chambers of the heart. So when the blood has to come down to the ventricles, the Atria, they start contracting. Where the Atria contract, the blood comes down into the ventricles, clear? So the ventricles, they dilate or they relax, and hence the blood is poured from Atria into the ventricles. So from here, the blood comes down, right? Now, what happens when the blood comes into the ventricles? So when blood from Atria, it comes into the ventricles, now the blood is under a very high pressure, but there are walls which are present between these Atria and the ventricle. So they, they get closed, and they prevent the backflow of blood into the Atria. Now the blood is under pressure and it tends to go back, but flaps will not allow the blood to go back. So, uh, there, the passage basically closes, and now the blood has only one way. From, if we talk about the right side of the heart, from right side of the heart, so blood will go through pulmonary artery into the lungs, and from left side of the heart, blood will move into aorta and go into the different parts of the body. So this is the only way left in front of the blood. So how will blood do that?
Now, if you look at the walls, so if you look at these walls which are present between the lower parts of the lower chambers of the heart and the blood vessels, if you see, so these walls are pointed away from the ventricles, away from the mouth of the ventricle, away from the end of the ventricles, right? So what will happen now? Blood will flow from here to this part, right? And they will actually tend to open the flap, they will flatten the flap, and the, the wall will open like this, and the blood will flow out, right? The same is in this case also. The blood will tend to open the flap of the wall, and it will move into the blood vessel. And if blood, blood wants to come back to the left, into the ventricle, so what will happen now? When the blood will try to come back, so blood will, so this is a blood vessel, right? So if the blood tries to come back, so it will, the blood will fall over here, and it will tend to close the flap of this wall, hence the blood will not flow back into the lower chambers of the heart, clear? So I hope this is clear, and this is, this, uh, the complete circulation of blood inside the heart is clear, right? So let us recall it once again. So there are four chambers of the heart, right? So upper two are oracles, lower two are ventricles. Now, in between oracle and ventricle, there are, there are walls. From ventricle into, when the blood is going into the blood vessel, so again, there are certain walls which prevent the backflow of the blood. So blood will, when blood will be there in the oracles, oracles will contract, and blood will flow down into the ventricles. Ventricle will relax, and they will expand, they will dilate. Blood from oracles will come down into the ventricles. From now, these flaps, if you see the direction of the flap, they are like this, from upward to downward. So when the blood will fall over here, the, these two flaps will open like this, and blood will flow into the ventricle, clear? Now, when these walls, they, when the blood has to flow from the lower part, lower chambers of the heart into the blood vessels, so if this is the lower chamber of the heart, and this is the blood vessel where the blood has to go. Now, the, the walls are like this. So blood from here will go here, it will push the wall, and the wall will open like this, and the blood will enter into the blood vessel. If this blood from the blood vessel tries to come back into the lower chamber of the heart, so when blood will fall over here, so it will lead to closing the closing the flap of this valve like this, and hence the blood will not come back to the lower chambers of the heart, that is the ventricles of the heart, clear? So I hope the complete circulation of blood in the chambers of the heart are very much clear to you.
Now, talking about the next topic that is the heartbeat, which is also called as a cardiac cycle. So that, which you hear when you, um, when you watch movies, when you, when you put your hand on your chest, so every time you feel that your heart is doing that, so what is it? It is a heartbeat. So there are basically the two steps of the heartbeat. The first one is contraction phase, and the second one is a relaxation phase. So contraction phase is called as systole, and, uh, this expansion or relaxing phase is called as a diastole. So every, a full heartbeat, it lasts for 0.85 seconds. So not even one second, it is 0.85 seconds. So the time duration of a complete heartbeat is 0.85 seconds. So the arteries, the arteries will, they, there are different phases, right? So for, there will be contraction of the Atria or the, uh, or the oracles. So that lasts for 0.15 seconds. Then there is a systole or the contraction of ventricles. Now, the ventricles will also contract. So that time period is 0.30 seconds. And the last is when both the chambers, both the Atria and both of the ventricles will relax. So that time duration is the longest, that is 0.40 seconds, right? So there are some important terms which are associated with the heartbeat. Now, the first term is ventricular diastole, when the ventricles are relaxing, they are expanding. So that is called as ventricular diastole. Atrial diastole, when the arteries are relaxing. Then when both of them are relaxing together, right? Now, both of them, they are in a relaxed mood. They just want to relax. They do not want to do any work. So when both of them are in the relaxed state, so that particular situation is termed as joint diastole. Joint diastole means when both of them jointly are relaxing. They, they just want to sit and relax now, right? Then the cardiac cycle. The whole sequence of event in the heartbeat is called as cardiac cycle, clear? So these are some of the important terms from this topic, heartbeat.
Now, the different phases of heartbeat, that is the cardiac cycle. So what will happen? How, what are the different phases? So basically, there are two phases, one is contraction, and one is relaxation. So when the arteries will contract, so that term systole is given to contraction, and diastole is for relaxation. So when these arteries will contract, blood from arteries will move down into the ventricles, right? So this is the first phase, that is atrial systole and ventricular diastole. So what will happen? The blood will enter into the upper chambers of the heart, and from upper chambers, the blood will go into the ventricles through this tricuspid and bicuspid valve, that is mitral valve and the tricuspid valve, right? So from here, the vena cava will close, the pulmonary vein will also close, and the blood will flow down, correct? So this is atrial systole and ventricular diastole.
Now, the second phase that will come is ventricular systole and atrial diastole. So here ventricles will contract, and it, I mean, the upper chambers of the heart, they will start relaxing. So when do you see here, the, the lower chambers of the heart, they are contracted. They are, there is a contraction in those, those chambers, right? So when these chambers will contract, blood will flow out into the, into the, uh, corresponding, into the corresponding blood vessels, right? So from here, the blood will go into this pulmonary artery, so that blood can be taken to the lungs for oxygenation, and from left side of the heart, blood will be taken by aorta to the body parts, right? So that oxygen can be delivered to all, all the parts of the body, clear? So this is ventricular systole and atrial diastole. So at this moment, so the papillary muscles will hold those chordae tendineae at position, so that these walls, due to contraction of the ventricles, these walls do not open, and blood do not go back from ventricle into the atrium. So this backflow is prevented by these walls, and who helps it? That is clear. So I hope this is clear. Let us see, uh, in a tabular form, the difference between the two phases of the cardiac cycle. So one is the atrial systole. So in atrial systole, the Atria's muscle will contract. There will be opening of the vena cava, and the pulmonary vein will close, clear? Then blood will enter into the ventricle by crossing through these bicuspid and tricuspid valve, clear? Bicuspid valve is on the right side, and, uh, sorry, tricuspid valve is on the right side, and bicuspid valve is on the left side of the heart. The semilunar valves at the roots of the pulmonary artery and aorta will close by producing a sound, "dub", right? So the sound of the heart is clear. So when the semilunar valve, which is present at the roots of the pulmonary artery, which carries this deoxygenated blood to the lungs, right? So this particular valve will close, and aorta will also close. Um, so this will lead, this will produce a sound which is "dub". Then the Atria will draw blood through opening of vena cava and pulmonary vein. Now, the Atria, the upper chambers of the heart will draw blood through the open, through opening of those vena cava and the pulmonary vein, clear? And when there is a jerk in the tricuspid and bicuspid valve, so that jerk will produce "lap", "dub" sound, right? So there are two sounds, lab and dub, right? So lab, the, dub sound. Lab sound will be produced when the walls between Atria and ventricle, both the walls, tricuspid and the bicuspid, both of them will close with a jerk. Then the sound "lab" will be produced. When the other two walls, which are present at the roots of the ventricles, when they will be closed with a jerk, so they, that will produce a sound "dub", right? So lab, dub, clear? So lab, when the, uh, the walls which are present between Atria and ventricle will close. And when, uh, when the walls present between, uh, the, of, between any blood vessel, between the blood vessel and the roots of the ventricle will close, that will produce a sound "dub", clear?
Now, ventricular systole. Ventricle systole is when, when there is contraction in the ventricular muscles, so blood passes into aorta and the pulmonary artery through semilunar valves. The Atria draw blood through opening of vena cava and pulmonary vein. So I hope these two phases of our heartbeat or cardiac cycle are clear to you.
Now, the heart sounds. So we have studied two sounds, lab and dub, right? So the first sound that is produced is "lab", which, which is produced when atrioventricular valves will close sharply, leading to the ventricular systole, when the ventricular systole will start, right? So that sound will be "lab". Then the second sound that will be produced at the beginning of the ventricular systole, so the semilunar valves at the roots of the aorta and the pulmonary artery get closed. So these, same is on the closure of the semilunar valves, the sound "dub" is produced.
Now, the rate of heartbeat. So there are different types of species, and different type of species have different rate of heartbeat, that is beats per minute. So even in the individuals of the same species, this rate, rate of heartbeat, it varies. So first is whale, so whale is 15 beats per minute. Elephant is 25 beats per minute. Horse is 40 beats per minute. Adult man is 64 to 72 beats per minute, whereas in case of adult women, this is even more. The rate of heartbeat is more, that is 72 to 80 beats per minute. For cat, it is 120 beats per minute. For a newborn infant, it is 140 beats per minute. Then for rat, it is 250 beats per minute. And talking about sparrow, when sparrow is doing a vigorous activity, say the, when the sparrow is flying, so at that particular time, it is 800 to 900 beats per minute.
The next topic is pacemaker. So when a heart beats, one heartbeat is over, the next heartbeat has to start. So a new heartbeat needs an impulse or it needs a command which starts the heartbeat, and it arrives in the pacemaker. It is also called as sinoatrial node or SA node, right? So this is sinoatrial node or SAN. So it is basically, uh, present in the upper right oracle, right? So oracle is always the upper part, upper chamber of the heart. So it is located in the walls of the right oracle. So this impulse is relayed to the ventricles through some special conducting fibers. So what starts the, what who gives the impulse or the command to start the heartbeat? So that is SAN, that is sinoatrial node, which is present in the walls of the right Atria. Now, this pacemaker or the SAN, it is present at the opening of the superior vena cava. So this is the, this is the vena cava which receives blood from the upper chamber, sorry, the upper parts of the body, right? So SAN is present at the opening of the
The superior vena cava. Then there is AVN, that is the atrioventricular node, which is present near the inter-auricular septum, near the tricuspid wall. So, basically, it is also present on the right side of the heart. There are certain bundles of muscle fibers which begin from AVN, that is the atrioventricular node, and it extends till the interventricular septum. And these muscle, these bundles of muscle fibers are called as the bundle of His. So, these basically consist of branches of fibers, and these branches of branches of fibers, they run along the walls of the ventricle. So, these are the bundle of His, present in the walls of the ventricles, and these are called as Purkinje fibers. So, these fibers all together, they, they, they help in creating an impulse and conducting this impulse in all the parts of the heart, right? So, it is the role of these fibers to create an impulse and conduct the impulse into the different parts of the heart.
Let us now move on to the blood vessels. So, there are three types of blood vessels. So, what are these blood vessels? Basically, these are the branched tubes which extend from the heart to different parts of the body. So, these are of three types: one is artery, then veins, and then capillaries, right? So, arteries, veins, and capillaries, these are the three main blood vessels. Starting with the artery, so artery, it is a blood vessel which carries blood away from the heart. So, whenever the blood is going away from the heart, so that blood is carried by arteries, right? So, for example, just to recall, we were talking about the blood that was going from the right ventricle to the lungs. So, from, uh, so if this is, these are the four chambers of the heart, so right atrium, right ventricle, left atrium, and left ventricle. So, that blood which was going away from the right ventricle into the lungs was taken by whom? It was taken by the pulmonary artery. So, when the blood was going away from the left ventricle to the body parts, so who was taking this blood? So, it was taken by whom? It was taken by the arteries, right? So, I hope this is clear. So, there are certain characteristics which, which helps these arteries to take blood. So, now we know that the blood is taken away from the heart by the arteries. Now, this blood has to reach the various different parts of the body, and that too, very far away from the heart. So, this blood is very much under pressure, right? So, how these, uh, arteries are able to cope up with this pressure? So, they have thick muscular walls and they have narrow lumen. Now, the blood in it flows in a spurt, which corresponds to the ventricular contraction of the heart. So, as soon as the ventricle will contract, the blood will flow with pressure into these arteries, clear? So, I hope this is clear. So, this is an artery which has a narrow lumen. This is the external connective, this is the external layer of the connective tissue which is present in the arteries. Now, the middle layer, this one, right? So, this is the middle smooth middle layer which is made up of smooth muscle cells and the elastic fibers. This is endothelium, and this one is the narrow lumen. So, it has thick walls, right? So, compare this artery with the vein. So, it has a very thin wall, but the arteries have very thick walls because the blood is very much under pressure when the blood is traveling through the arteries.
Now, the blood vessel will, so vein is the blood vessel which carries blood from an organ towards the heart. So, whenever the blood is going towards the heart, we are, that blood is taken by veins. So, what are the different characteristics? They have thin muscular walls, they have wide lumen, and the blood that is flowing into through it is uniform flow, right? So, blood in, uh, in it flows uniformly and it contains thin pocket-shaped valves. So, there are certain valves that prevent the backflow of the blood, clear? So, as you can see, these are the veins. So, veins have these valves which pre, which allow the blood to flow only in one direction, and they prevent the backflow of the blood. So, these are the pockets which will, uh, which will get, as soon as the blood will go from there, the valve will close, right? So, blood presses the wall and the wall gets closed. Wall gets closed in case the blood tries to come back, come in the opposite direction, right? So, the blood actually presses the wall and the valve gets closed. So, over here, the veins, what is the main difference between arteries and veins? So, uh, vein, the arteries, arteries are the blood vessels which carry blood away from the heart, and veins are the blood vessels which carry blood towards the heart. Now, if we talk about the structural difference, so the structural difference is this that the arteries, they have thick walls and they have a narrow lumen, but in case of veins, veins have thin walls, but they have a wide lumen.
Now, the next blood vessel is arteriole. So, arteries are basically the smallest and the final branches of the arteries. So, these are called as arterioles. So, they are highly muscular and they can change their diameter manifold, right? So, they, their diameter can be changed. Now, the arterioles finally break up into capillaries. Now, these are the arterioles, right? So, these are the small arterial capillaries. So, these arteries, they basically break up into these small, small capillaries. The last blood vessel that is the capillary. So, capillary is a very narrow tube which has eight micrometer diameter. And what are the characteristics? So, the walls consist of a single layer of squamous epithelial cells, that is endothelium. So, they are single cell thick, right? They have no muscles. And the total number of blood capillaries that are present throughout the body are almost inconceivable, right? There are so many arteries that you cannot actually count them. So, there are this much number of capillaries that are present throughout our body.
Talking about the functions of capillaries, of, uh, these capillaries, they allow outward diffusion of oxygen into intercellular fluid and from there into the tissue fluid. So, they actually allow the diffusion of oxygen in, into the intercellular fluid that is present between the cells. So, from capillaries, this oxygen gets diffused into this intercellular fluid, and from this intercellular fluid, it goes into the tissue fluid. Second is, it allows inward diffusion of carbon dioxide from the intercellular fluid. Now, where it is delivering oxygen, now it will take up something back, right? So, the waste that is carbon dioxide is taken back by these, uh, capillaries by simple diffusion, and it is taken to be thrown out of the body. It allows inward and outward diffusion of substances like glucose, amino acids, urea, and hormones. So, as there was inward and outward flow of gases, in the same way, there is diffusion of some other substances like glucose, amino acids, urea, and hormones also. So, it also allows leukocytes to squeeze out through the capillary walls and by the means of the amoeboid movements. So, leukocytes, what are those? Those are the WBCs, right? So, we have studied diapedesis, right? So, they actually allow the, uh, these WBCs, these leukocytes, they can actually show amoeboid movement and they can change their shape and they can move out. They can go into these narrow capillaries also. So, they allow leukocytes to squeeze through these capillary walls, right, which actually shows the amoeboid movement of these leukocytes.
Now, these blood capillaries, they can, they have a power of dilation as well as they have a power of contracting. So, the power of dilation, when they dilate, it is called as vasodilation, and when they contract, it is called as vasoconstriction. Now, when they dilate, this increases the blood supply to all the parts of the body because they are present where arteries and veins cannot reach, right? So, basically, they are connected from cell to cell. They are connecting all the cells, right? They are providing oxygen and other useful substances to all the cells of the body. And when they contract, it decreases the supply of blood to the different parts of the body. Now, these small, small arteries, these capillaries, they actually finally they reunite and they form a larger blood vessel. And the smallest united common branch is venule, which forms the larger veins. So, this is, these are the small, small venule capillaries which have reunited and then they have formed this common branch which is called as venule, which is supposed to be the smallest united common branch, right?
Now, the difference between arteries and veins. So, arteries, what is the function of arteries? So, arteries are the blood vessels which carry blood away from the heart into the different organs. Now, veins, veins are those blood vessels which carry blood towards the heart, right, away from the organs. Arteries, they are progressively, they get branched and they start decreasing their size, starts decreasing, whereas veins, they progressively unite. So, as we saw that picture, the artery, it was, arteries were actually branching, branching, so they were decreasing in size, whereas veins, they were progressively, they were reuniting and they were increasing in size, right? Now, the smallest artery breaks into arterioles, whereas the smallest vein arises from venules, clear? The arteries, they have thick and muscular walls, whereas veins have thin and less muscular walls. The next one is the walls of the arteries, they are elastic, whereas the walls of veins are non-elastic. The walls, uh, the lumen which is present inside the arteries is narrow, whereas in case of veins, it is wider. In case of arteries, they have no valves in their inner lining, and in case of veins, veins have valves in their inner lining which prevent the backflow of blood. So, valves are not present in arteries, but they are present in veins. Arteries, they constrict or dilate to control the blood flow, whereas veins, they do not constrict. So, there is no constriction in the veins. Then you are talking about the artery, so arteries are usually placed deeper, right? Whereas veins are more superficial. So, you can see the veins, uh, through your skin, whereas arteries cannot be seen. Now, the arteries, they do not collapse even when they are empty, but veins, if they are empty, they will collapse. The next difference between arteries and veins is the blood flows with a jerk and under great pressure. So, that is why they have thick muscular walls, whereas in case of veins, the blood flows uniformly, continuously, and with very little pressure, clear? Then in case of arteries, they carry fully oxygenated blood. So, it initially, when you study the difference between arteries and veins, you study the difference as arteries carry oxygenated blood and veins carry deoxygenated blood, but that is not true. All the arteries, they do not carry oxygenated blood except one. So, all of them carry oxygenated blood except one, and what is that? That is the pulmonary artery, which carries blood from the right ventricle to the lungs, right? And veins, they carry partially deoxygenated blood and carbon dioxide laden blood, right? Except for the pulmonary vein, because pulmonary vein carries blood from lungs to the left ventricle, right? So, these are the two exceptions for them, clear? So, I hope the differences between arteries and veins are clear to you.
The next that we are going to talk about is two blood circulations in our body, and they are pulmonary and systemic. So, pulmonary, it pertains to what? It, wherever the pulmonary word comes, so it means we are talking about lungs, right? So, the circulation between heart and lungs, so that is the pulmonary circulation, and it is a very short circulation. The second one is systemic circulation, where the blood flows between heart and the different parts, the general parts of the body. So, this circulation is very long because the body is very huge. So, the blood has to travel a long distance. So, this is a long circulation. So, since there are two types of circulation and in a single circulation, blood comes twice through the heart, so it is called as double circulation. So, as you can see, this is the heart, these are the lungs, this is the body, right? So, the blood when it goes from heart to lungs, and so this blood is carbon dioxide rich or deoxygenated blood. From lungs, this blood comes back to the heart, right? So, this is oxygenated blood. Now, from heart, this blood goes to the body parts, this is oxygenated blood, and from body parts, this will go back to the heart, so it will be a carbon dioxide rich blood. So, in a single circulation, the blood comes twice into the heart. So, this is called as, that is why it is called as double circulation.
Hepatic portal system. So, when we are talking about hepatic, so it means we are talking about liver, right? So, the blood which comes from stomach and intestine, it does not directly go into the right side of the heart, that is the right, uh, atrium, correct? Because right atrium has carbon dioxide rich blood, that is the deoxygenated blood. But the blood that comes from the small intestine and, uh, sorry, the intestine and the stomach does not go directly to the heart, but it passes through the liver. So, first of all, it will enter into the liver. From liver, these, it then, these vessels then join the hepatic portal vein. From hepatic portal vein, they will again branch into small, small capillaries and finally join to form a single vein that is called as a portal vein. Portal vein then combines with vena cava and pours all the deoxygenated blood into the, uh, carb, into the right atrium, clear? So, this is how the blood that is coming, the deoxygenated blood that is coming from stomach and small intestine does not go directly into the heart, but it goes through the liver. This hepatic portal system has a very important role to play. Now, the food is digested and absorbed, absorbed in stomach and small intestine, but all of them does not need to be circulated throughout the body. So, first, all the blood that comes from, uh, from stomach and intestine, it enters into the liver. In liver, excess of glucose is stored as, as glycogen, and there are certain poisonous substances which are being absorbed by the blood. So, these are then detoxified in liver, and rest of the blood is sent to the heart for purification.
Let us talk about the important blood vessels which are connected to the heart. So, the first one is the blood vessels entering the heart. So, the first is superior vena cava. So, it receives the blood from upper parts of the body and pours it into the right atrium. Second is posterior vena cava, which is inferior vena cava. So, it receives blood from lower parts of the body and drains it into the right atrium, correct? Then is pulmonary vein. So, pulmonary veins, these are the two veins that come from each lung and then pour the blood into the left atrium. So, the blood that comes from lungs is oxygenated, and the blood that goes into the lungs is deoxygenated, right? So, when this pulmonary vein, so these two pulmonary veins, they are coming, right? So, these two are coming with oxygen-rich blood and they are pouring the blood into the left side of the heart, that is left atrium, clear? Now, the blood vessels leaving the heart. So, there are certain blood vessels which are taking blood away from the heart. So, the one is that is taking blood towards lungs, right? So, that is pulmonary artery, clear? Other one is aorta, which is taking blood to the body parts from the left ventricle to the body part, so that is aorta, clear? So, I hope the heart vessels are clear to you.
Now, the next is blood vessels entering liver. So, all the blood vessels that are entering the liver. So, liver, there is one hepatic artery. So, it from aorta into the liver. From aorta, so aorta brings oxygenated blood from heart. So, this hepatic artery brings this oxygenated blood from aorta into the liver. The next one is hepatic portal vein. So, as we already discussed, the blood from stomach and intestine does not go directly into the right side of the heart, but it passes through the liver, so that the extra things can be absorbed and stored in liver, and also the poisonous things can be detoxified by liver, correct? So, this hepatic portal vein from stomach and small intestine into the liver. The next one is blood vessels leaving the liver. So, what are those blood vessels which are leaving the liver? So, this is hepatic vein. The vein from liver into the posterior vena cava. So, there is a vein, so this is liver, right? Okay, so this is little funny kind of a liver, clear? So, something like this. So, this is liver. So, there is hepatic portal vein which is entering into the liver, and now it is branching into different capillaries. Now, these capillaries, they are joining together and coming out. So, this is called as hepatic vein. So, this hepatic vein joins into posterior vena cava, that is inferior vena cava, we also call it as, right? So, then it pours all its blood into posterior vena cava, and from posterior vena cava, it goes into the right atrium where there is deoxygenated blood, clear? So, I hope the blood vessels entering and leaving liver are also clear to you.
Now, the next blood vessels related to kidneys. So, the blood vessels entering the kidney. So, whenever you come across a word called renal, so renal means we are talking about kidneys, right? So, renal artery from aorta enters into the kidney. So, this has a, this is full of blood which is supplied to kidneys, right? Then the blood vessel leaving the kidney is renal vein. The kidney into the posterior vena cava. So, that carrying the deoxygenated blood, right? So, this deoxygenated blood is carried from, um, from kidney to the heart by renal vein. Renal vein pours all the deoxygenated blood into the posterior vena cava, clear? So, there are certain words. One is pulmonary, so pulmonary, whenever you come across a word pulmonary, it means it is somewhere related to lungs. So, we are talking about something related to lungs. When we are talking about the renal, so that time we are talking about kidneys, right? And when we are talking about the word hepatic, so this means we are talking about liver. So, these are certain words that you can remember and you can relate to.
Now, the pulse. So, arteries, they are elastic, they have muscular walls. Now, when the blood is passed through these, uh, arteries, so they, they tend to swell and then they tend to relax, right? So, this makes pulse. So, what happens? This is alternate expansion, alternately they expand and they recoil. The recoil, the recoil of the walls of the arteries during ventricular systole. So, when heart beats, when, when ventricle, when heart, when the ventricles of the heart, the lower chambers of the heart, they contract, at that particular time, the arteries' walls, they swell and they relax, right? So, this leads to the formation of pulse. If you take these two fingers and you put it on your wrist where you can see two blood vessels superficially, so you will feel pulse, right? You will feel, um, the heartbeat, right? So, that is called as a pulse.
Blood pressure. So, pressure with which the blood flowing through the arteries exert on the wall. So, when the blood is flowing through the arteries, the, this blood actually exerts a pressure on the walls, and this is called as blood pressure. So, there are two, two types of blood pressure. One is the upper limit, one is the lower limit. The upper limit is called as systolic pressure, and the lower limit is called as diastolic pressure. The upper limit, when is it? It is a point or a time when the fresh blood is flowing through the arteries, right? So, at that time, what will happen? So, there will be expansion, the, um, the walls of the arteries, they will swell, right, as a result of the ventricular contraction of the heart. And the second one is lower limit, which is called as diastolic. So, when there is contraction, right? So, sorry, when there is a relaxation of these arterial walls, so it happens once the blood has passed. After that comes the lower limit of the blood pressure or the diastolic pressure, which is called as the diastolic pressure, right? So, the normal blood pressure, if you talk about an adult human, the normal blood pressure is the upper limit, that is systolic, is 100 to 140 mmHg. HG is mercury, right? And the lower limit is 60 to 80 mmHg, right? So, this is systolic and diastolic pressures. When the blood pressure level goes up above 140 and 90. So, the upper level goes above 140, and lower level goes above 90, that is systolic and diastolic, so it is known as hypertension. It is measured by an instrument which is known as sphygmomanometer.
Coming on to tissue fluid or intracellular fluid. So, it is also called as extracellular fluid. And what is it? So, it is basically when the blood flows in the blood capillaries of the tissues, so at that time, some plasma, some leukocytes, that is WBCs, so they leak out of the walls, right? And then they go into the, the, into the intercellular spaces where they bathe the, they make the fluid that is present between the cells, right? So, it is called as tissue fluid. What is its function? What is the function of tissue fluid? So, the function of tissue fluid, the cells they absorb oxygen and other required substances from the fluid. So, this fluid is rich in oxygen, it is rich in some other substances which are required by the cells, and in turn, these cells, uh, when they respire, they produce carbon dioxide. So, this carbon dioxide and other waste products are given back to the tissue fluid, and these are taken away from the cells and they are thrown out of the body.
Lymph and the lymphatic system. So, there is blood which is flowing in, in our body, right? And there is lymph which is flowing in our lymphatic system. So, there is some fluid which is absorbed back by the blood vessels, and most of it enters in the minute channels which are called as lymph vessels, and this fluid which enters the lymph vessels is now called as lymph. So, the lymphatic system, it is also widely distributed. These lymphatic vessels, these are widely distributed in our body. Now, some of the fluid, it enters into the lymph vessels which makes lymph, and from lymph, this lymph is actually very, very helpful, very, very useful to us also. Now, lymph, it goes into the lymphatic vessels by the contraction of the muscles, right? So, from lymph vessels, this lymph goes into the lymph nodes. From lymph nodes, these go into the anterior veins, which then drain this lymph into the right atrium, right? From right atrium, then again, it is, it goes back into the circulation throughout the body. So, this is how this lymph flows through the lymphatic system and then re-enters into the blood system, sorry, blood circulatory system. So, this lymph is composed of cellular part, as our blood has some cells, right? So, they only have leukocytes. There are no RBCs and there are no blood platelets. So, all of them, when WBCs, RBCs, and platelets are present, so it makes blood. Now, now, when only WBCs are present, it makes lymph, right? Then non-cellular part also, as blood has, right? So, it has 94% of water. The solid that is fats, proteins, carbohydrates, enzymes, and certain other substances, they constitute 6% of this non-cellular part.
Now, since this lymph is flowing through our body, right? And we are studying in so much of detail about lymph, so what is the function of lymph? So, lymph is very nutritive. It supplies nutrition. It supplies oxygen to those parts where blood cannot reach. So, blood cannot go to each and every cell, right? So, there are certain restrictions where blood can flow, but this lymph can actually reach those cells where blood cannot reach. So, they provide nutrition and oxygen to those cells of the body. Then drainage. So, now it drains the excess tissue fluid and metabolites and returns proteins to the blood from the tissue spaces. Now, inside the tissue spaces, they are tissue fluid, right? So, all of them is not needed there. Everything is not needed there. So, it drains back this extra tissue fluid into the, into the blood, clear? Then next is absorption. The lymph, there are fats which from intestine, these are absorbed through the lymphatic, these lymphatic system, these lymphatic capillaries, right? So, absorption of fats is done by lymph. The next is defense. So, talking about defense, so in defense, there are lymphocytes and there are monocytes, right? So, uh, their, their function, it is to defend our body. Their function is to fight against the infections that might enter our body. Those pathogens which might cause infections and they enter into our body, so lymphocytes and monocytes actually defend our body against these infections. So, you must have heard about lymph nodes that we spoke a few, few minutes earlier, right? And then you have spoke about tonsils also. You have heard about tonsils also. So, these lymph nodes, what do they do? So, they try to, they try to localize the infection. They prevent this infection from spreading into various parts of the body. So, and now lymph nodes are part of what? So, they are the part of lymphatic system. So, this is how they defend our body. And secondly, the tonsils, tonsils are also the lymph glands, right? So, what are tonsils? Tonsils are the lymph glands.
The next organ is spleen. So, spleen is a large lymphatic organ which is the size of a clenched fist. Fist and it is reddish brown in color. Where is it situated? It is situated behind the abdomen where there are kidneys. So, this is a kidney and above kidney, you will see spleen, right? So, what are the functions of spleen? Spleen acts as a blood reservoir in emergency, for example, in case of hemorrhage or in case of stress or in case of carbon monoxide poisoning. So, it also produces lymph and it destroys the worn out RBCs. So, worn out RBCs are destroyed in blood. So, we have, sorry, in spleen. So, we have already discussed this when we were discussing the fate of RBCs, their life cycle, and about their death. Then spleen in an embryo, the spleen is the organ that produces these RBCs, clear? So, I hope the functions of spleen are also clear.
So, now is the time to discuss certain some questions from the topics which we have discussed today. The first one is given below is a highly schematic diagram of human blood circulatory system. So, A is which part? State the number represents heart. So, which part represents heart? Give reason to support your answer. So, which number? So, tell me the number. So, it is 3, right? So, 3 represents heart. Why? Because 2 will represent lungs. So, this is the upper part of the body, this is the lower part of the body, right? So, from heart, there are there are many, uh, different, uh, what do you call them as, uh, different blood vessels which carry blood. So, you can see from 3, there are blood vessels which are carrying blood towards lungs, away from the lungs, towards different parts of the body also, right? So, the 3, the number 3 represents heart. Now, B part of the question, which numbers represent the following respectively? First is aorta. So, aorta, from where, what from where does it arise? So, it arises from heart and it takes oxygenated blood from heart to different parts of the body, right? So, 5. So, this is 5 will represent aorta, right? Then hepatic portal vein. So, hepatic portal vein, so it will arrive, it will, uh, the blood coming from stomach and intestine will go into the hepatic portal vein. So, it will be somewhere near the liver. So, if you see this, uh, so this is intestine, this should be stomach, right? So, both of them are are there. The blood is going away from stomach and small intestine and it is going through this hepatic portal vein. So, the answer is going to be 7. Now, the pulmonary artery. So, pulmonary artery, so this is the artery which carries deoxygenated blood from the right side of the heart to the lungs for oxygenation. So, this is heart. Now, which, which part, which blood vessel, which number is taking, um, the deoxygenated blood away from the heart? So, that is number 1. So, this is going to be 1. Then superior vena cava. So, superior vena cava is the part which actually brings blood from the, it is the blood vessel which brings blood from the upper body parts to the heart for oxygenation, right? So, so basically, they bring deoxygenated blood. So, which number? So, this number that is 9. So, this is 9. Now, the renal vein. So, what does the renal vein do? So, renal vein, it is related to what? It is related to kidneys, right? So, these are the kidneys. So, they will take blood away from the kidney towards heart, right? So, the number will be 8. And stomach. So, very simple. So, this is what? So, this is stomach, that's, so that is number 10, clear? So, I hope this was easy and clear to you.
Question number two. The figure given below shows a diagrammatic cross section of three kinds of blood vessels A, B, and C. So, identify A, B, and C. So, A, if you look at A, the lumen is very narrow, and there are red cells, right? So, A will be what? A will be artery. Talking about B, so these walls are thin, and the lumen is very wide, so it is vein, clear? Now, the C, the last blood vessel that is left that we have studied is capillaries. So, these are very narrow and they are single celled thick, clear? So, these are the capillaries. So, let's start the B part of the question. Name the parts 1, 2, 4. So, 1, 2, 3, and 4. So, what are they? So, the first one is, so this is artery, this is vein. So, the outer wall is called as what? So, it is called as a connective tissue layer, right? So, the inner one, so over here, 2 is this, right? And 2 and 2. So, this is what? So, this is lumen, clear? Now, talking about 3, so we are talking about this part, this layer. So, this is the muscular layer, which layer? The muscular layer. Now, the last is the innermost layer. So, innermost layer is called as endothelium layer. So, I hope this question is clear. C part, mention the structural difference between A and B. So, in A, artery, and vein, what are the structural differences? So, the first difference is the lumen is in first case, it is wide, and in this, sorry, in case of artery, it is narrow, and in case of vein, it is wide. Secondly, the second is the wall, right? So, the muscular wall. So, the muscular wall of artery is thick, and the muscular wall of vein is thin as compared to artery, right? So, I hope the structural differences are clear. D part of the question says, name the kind of blood that flows through A and through B respectively. So, the A, which is artery, so mostly the blood that flows through artery is oxygenated, except for pulmonary artery. And from B, it is deoxygenated blood, except for pulmonary vein, clear? E part, in which one of the vessels referred to in as A above, does not exchange, does the exchange of gases take place? So, exchange of gases, so we plugged three blood vessels, right? Arteries, veins, and capillaries in the A part, clear? So, out of them, the exchange of gases takes place only through capillaries, why? Because they are single celled thick, right?
Next question is, a diagram below represents human heart in one phase of its activity, right? So, we have studied two phases, contracting and expansion. So, where, what phase is shown in this? The first is, name the phase. So, what phase is shown over here? So, if you see the diagram, so it is very clear that the ventricles are contracting, why? Because the walls between atrium and ventricle are closed on both the sides, while the walls which are present between the ventricle and the blood vessels are open. So, this is ventricular systole, right? So, this is ventricular systole. Now, which part of heart is contracting in this phase? Give reasons to support your answer. So, in this particular phase, the ventricles are contracting. How? Because the walls between the ventricle and the blood vessels are open, and they are pushing the blood into the blood vessels, right? So, that is why we know that the ventricles are contracting, and, uh, over here, the atria, or the atria, they are relaxing, okay? So, I hope all the topics, all the questions that we discussed in this particular chapter are clear to you. So, we will now meet in our next video where we are going to discuss our next topic. So, till then, you take care, and as you all know, learn or have free helper best hair.