thank you in this video what we are going to be looking at is the human heart and we are just going to see a simplified structure of the human heart because the actual human heart when you look at the internal structure is much more complicated but for the purpose of this video I've decided to keep it as simplified as possible because we just have to see the important parts within the heart and we have to understand their basic fundamental structures so the human heart itself the first thing that we have to understand is it is actually divided into two sides which are the left and right side now remember the when you're labeling the left and right side of the heart it is actually flipped so in my diagram over here right becomes left and left becomes right the reason is because when you look at the human body when you look at a person's uh when you when you compare the person's body over there you can see that that the highlighted part in yellow is the left part of the body uh the yellow color highlighted parts and the pink color highlighted area is the right side of the body that is why the left and right portions are actually flipped when you're looking at it so it's like looking at a mirror image technically so in this case what actually happens is we have to know that the two sides of the heart are separated by something known as the septum which is a muscular wall and the function of the septum is just to prevent the blood from the right side and the blood from the left side from mixing with each other next thing we have to know about the heart is the heart has four chambers or four rooms and the four chambers are known as the left and right Atria and also the left and right ventricles some students will notice hey wait I came across this word atrium so which is it is it Atria or Atrium Atrium is singular and iteria are plural so when you want to just call it by itself left atrium or right atrium but when you're calling it together when you're grouping it together we can just say left and right Atria so um in my diagram as you can see that I am labeling it as l a l left L is for left atrium LVS for left ventricle R A is for like Atrium and RV is for like ventricle in the exam you cannot shorten it yeah so if you want to actually put it uh when you are writing it out please write out the holes and uh the whole word you have to write it out fully you have to say left atrium or left ventricle you cannot put the shortened acronym LA or LV that is not accepted in the exam I've just written it over there for our purpose of our simplification now also notice that L A and LV I have written it in the red color and R A and rvf returning blue color there is a reason for that I will explain that one later too so uh another thing that we also have to know is the heart is actually made up of cardiac muscles which I which I have highlighted in yellow and the cardiac muscles are actually quite different from these skeletal muscles in our body which are muscles attached to your bones or the smooth muscles in the body where you can find in your blood vessels or intestine the cardiac muscles have a rather interesting quality which is known as myogenic and I will describe this characteristic in a different video for now all we just have to know is the heart is made out of a special type of muscle known as cardiac muscles you do not have to know the structure of the cardiac muscles in detail that is a bit too much if we were to actually dive into it and the thickness of the muscles are also quite important so as you notice I've drawn out the chambers and I've also put circles on each of the walls you can see the left atrium wall is circled with the green color by Atrium wall light ventricle and the left ventricle wall as well now looking at the diagram which wall is the thickest the thickest the thickest wall is actually the left ventricle wall followed by the right ventricle wall which has a medium thickness and the thinnest wall are the atrial walls right atrium and left atrium both of them have very thin walls there is a reason why the wall thickness is as such we will talk about that part later too let's just go through the structure first the explanation part will come later in the video another very important thing to also know about the heart is they have valves now we have seen valves with uh the blood vessels veins in particular and uh the valves here have the same function because they prevent backflow you see under normal circumstances blood has to flow from the Atria to the ventricles on both sides which have represented in the arrows and between the atrium and ventricles there are valves which are known as the atrial ventricular valves and I've labeled it I've highlighted in yellow the left atrio ventricular valve and you might atrial ventricular walls the function of those valves are to make sure that the blood does not flow from the ventricles back into the atrium so that's what it does it makes sure that the blood only flows from the Atria two ventricles all right and after the blood flows into the ventricles what needs to happen is they need to flow into the arteries which I've represented in the arrows as you can see there one arrow is going outwards from The ventricle okay into that artery and another one in red color um and that's how the blood is supposed to flow out so to make sure that the blood only Flows In One Direction we have the semilunar walls which I have highlighted in green so the function of the atrial ventricular valves is to prevent the back flow from ventricles to Atria and the function of the semilunar valves is to prevent the backflow from arteries to ventricles so with the presence of these two groups of valves deoxygenated blood which I have represented in blue color they will flow into the right atrium into the right ventricle and then flow out of the heart and for the oxygenated blood which I've represented in the red color arrows they will flow into the left atrium left ventricle and out of the heart all the blood flows in one way because the valves are there to ensure that there is no backflow happening other important things that we also have to know about the heart is they are blood vessels connected to the heart well obviously because if you remember we studied the three types of blood vessels arteries veins and capillaries let's just focus on veins and arteries if you remember in the previous video veins are blood vessels that transport blood back to the heart and arteries are blood vessels that transport blood away from the heart so vein is the one where you can see the blood going into the heart and artery is the one where blood is going out of the heart again I've just labeled it over that because that's how the blood is supposed to flow into and out of the heart but these veins and arteries actually have special names and the special names are as follows pulmonary vein from the lungs aorta to the rest of the body vena cava from the rest of the body and pulmonary artery which is blood vessels transporting blood to the lungs or the word pulmonary in this case is derived from Latin which means lungs so pulmonary arteries means an artery that transports blood to the lungs and pulmonary vein is the blood vessels that transport blood from the lungs to the heart that is essentially what that means the next thing we must know is we must also talk about that weird lines which are located in the atrioventricular valves and those lines are referred to as something called chaudi tendine sounds like a very fancy name but you don't have to remember that special name all you can just call it is tendon they have a very special type of connective tissue and they're attached in a way where they're attached to the atrial ventricular Valves and The ventricle wall now the function of this tendons is to prevent the valves from from folding inside out now what do I mean by that you see under normal circumstances what happens is deoxygenated blood flows into the right atrial and oxygenated blood flows into the left atrium deoxygen deoxygenated blood as represented in blue and the oxygenated blood in red and from The Atrium they will then fill up the ventricles as we have discussed earlier and from the ventricles where they are supposed to go is they are supposed to go out of the heart now sometimes what may happen is if the heart does not function normally back flow may happen and back flow here means that from the ventricles they flow back into the Atria do we want this to happen no this is something that we do not want to happen because this can be dangerous so to prevent the backflow obviously what happens then the atrio ventricular valves will actually close so that's a normal thing and this ensures that the blood will flow up towards in One Direction so that's fine but the question is what do the tendons actually do imagine if the tendons were not there to attach itself to the atrial ventricular valves what will happen then is the atrial ventricular valves just like clothes in the Wind they will start flapping and when they start flapping they will actually fold inwards or therefore inside out look at what happens to the valves there's nothing attaching to it so the walls just fold inside out and that is dangerous we don't want that to happen because when the valves fold inside out look at what happens to the blood they might flow backwards into the Atria so this can be quite dangerous so with the presence of the uh tendons the tendons will ensure that the valves remain in place and when they close they just cup into each other and form a perfect fit and they will not flap backwards and cause the valves to flow to fall inside out that is just essentially the function of the tendons now we also have to talk a little bit about the muscle wall if you remember I'm just highlighting all the muscle walls if you remember I told you that the atrial walls which I've highlighted in yellow I hope you can see that the eight wheel walls are the thinnest walls the reason why the eighth wheel walls have to be the thinners is because the muscles they will just have to generate enough pressure to push the blood into the ventricles um so they generate sufficient pressure to push blood into the ventricles and look the distance between the atrium and ventricle is quite short so the muscles in the atrium do not have to contract very much they just have to give enough pressure to push the blood into the ventricles which is not far away however when we look at The ventricle walls I have highlighted the left ventricle wall in Orange and the right ventricle wall in green remember which wall is thicker between the two you're right the left ventricle wall is the thickest and the light ventricle wall has a medium thickness and of course the 8th Wheel wall is the thinness if you remember the left ventricle is supposed to push the blood into the aorta which goes to the rest of the body and the right ventricle wall has to generate pleasure to push blood into the pulmonary artery which transports the blood to the lungs so logically the right ventricle just has to generate enough pressure to push the blood to the lungs and the blood the heart and the lungs are not so far away so that is why the wall of the right ventricle does not have to be so thick it has to be thicker than the atrial walls definitely but it does not have to be extremely thick because the pressure is just needed to push the blood from the right ventricle from the right ventricle to the lungs not much of a great distance however from the left ventricle it has to generate pleasure to push blood to the brain to the liver to the intestines hands and feet and other parts of the body so therefore it the wall needs to be thick so it can generate the most amount of pressure to push blood to the rest of the body because it is of a greater distance from the heart that is why by different walls in the heart the atrial walls the left ventricle wall and the right ventricle wall they all have different thicknesses it just corresponds to the amount of pressure they need to generate atrial walls at the thinnest because they just need to generate very little pressure to push blood from the aturia to the ventricles right ventricle walls have to be thicker because they need to push blood to the lungs and the left ventricle wall has to be the thickest because it has to generate the most pressure to push blood to the rest of the body which are at a greater distance from the heart that's basically what we have to know about the structure of the heart for now