Cardiovascular System | Summary

welcome to this video on the cardiovascular system summary the goal of this video is to give you a recap of how the entire cardiovascular system works in one video okay so the cardiovascular system has two circulations there is the pulmonary circulation and its purpose is to pump blood to the lungs for gas exchange so let's write lungs in orange and we'll compare that with the systemic circulation and its purpose is to pump blood to all of the body cells for oxygen delivery as well as bringing nutrients and carrying away waste okay so when we look at the heart let's go ahead and start with the pulmonary circulation and the blood in in the heart the right side is deoxygenated so the right atrium is deoxygenated and blood goes through the AV valve which we'll talk about in a second to the right ventricle and then from that point when the heart beats the blood goes up and out to the lungs through the pulmonary arteries so let's go ahead and write this down so the right ventricle pumps deoxygenated blood out through the pulmonary arteries and these are vessels that are going away from the heart in this case they're deoxygenated and then they go into pulmonary arterioles which are small blood vessels small arteries that regulate blood flow so when you're exercising these will dilate to bring more blood and when you are resting they will constrict and then they go from there into the pulmonary capillaries and the pulmonary capillaries is where the magic happens this is the site of gas exchange oxygen enters the capillaries and carbon dioxide leaves so because of that I want you to take a pink highlighter and highlight pulmonary capillaries because this is where gas exchange then occurs then after this we'll use a pink plant pen because the blood is now oxygenated and it comes back through so it goes out the pulmonary capillaries into small veins and then into the pulmonary veins which are oxygenated blood vessels going back to the heart and then they enter the left atrium and they've now completed the whole circle where it went right atrium right ventricle pulmonary arteries to the lungs and then oxygenated blood returning to the heart through the pulmonary veins this chamber right here is the oops sorry is the left atrium and then oxygenated blood flows down through that bicuspid valve into the left ventricle so now we're ready to talk about the systemic circulation so the systemic circulation begins from the left ventricle and it pumps blood up and out the biggest artery in your body which is called the aorta and as you can see there are a lot of little blood vessels coming off the air not-so-little actually the first ones are the coronary arteries so the heart gets first dibs on the oxygenated blood and then you have three coming off the top of the arch that go to the rest of the upper body and then the blood goes down and later on this blood vessel is called the abdominal aorta and it can deliver all of the blood to the different organs such as the kidneys okay so the aorta it has a very high pressure and in fact this is essentially where you can get your reading for what pressure is so I'm going to take a purple pen and the ventricle is pumping a particular pressure and that systolic pressure is the pressure that the heart is able to exert when it ejects blood so that's going to be that top value so this is the ventricular force the pressure that it builds up in order to push the blood out and it's typically going to be about 120 millimeters of mercury that's why you've seen blood pressure as 120 over 80 for example this means the left ventricle built up to 120 millimeters of mercury to push the blood out and then when it's relaxing in between beats the pressure in here is only 80 millimeters of mercury we measure this indirectly on someone's arm but you're taking that from an artery that's coming off from you know the top of the arch and so it's an indirect measurement but it gives you a very good idea of what the pressure actually is in the left ventricle okay so back to our systemic circulation so from the aorta then there's a bunch of smaller arteries like the renal artery for example and then these continue to branch into smaller and smaller arteries until you get to the arterioles and just like I told you for the pulmonary circulation the arterioles are critical for regulating flow so for example if you're exercising the arterioles to your skeletal muscles and your legs would dilate and allow more blood flow to go there and at the same time the arterioles leading to the kidneys would constrict so there would be less blood flow to the kidneys at that time okay so then after the arterioles just like the pulmonary circulation now you go to the systemic capillaries these are microscopic blood vessels and they this is where exchange occurs so oxygen dropped off carbon dioxide gets picked up nutrients get dropped off and wastes get picked up so now take your blue highlighter to show that this is where that exchange happens and now we have deoxygenated blood that will return to the heart via veins so these capillaries drain into veins and veins are blood vessels that are returning to the heart and the veins get bigger and bigger until you get to the largest vein called the vena cava that then dumps back in to the right atrium and we've completed the entire systemic circulation at this point so the vena cava and actually all veins have low pressure and the pressure is so low that they have valves to prevent backflow and let's keep talking about valves for just a second so not only do veins need to have valves to prevent backflow but you have valves in the heart so separating the atria from the ventricles are the atrioventricular valves the one on the left side of the heart has two flaps so we call it the bicuspid because by means to and the one on the right side of the heart has three flaps so we call it the tricuspid and these are valves that prevent backflow when the ventricles contract and I'll show you what I mean by this so when the left and the right ventricle contract blood has just come in to them from their atria and they're squeezing upward and when they're squeezing upward blood needs to go into the aorta on the left side and into the pulmonary artery on the right side and the the valves here have to shut if they didn't that blood would go back into the atrium and that would be called a mitral valve regurgitation or a heart murmur or something there are also valves in the pulmonary artery and in the aorta and they're called the pulmonary semilunar valve and the aortic semilunar valve okay so next I want to explain briefly how electrical activity is conducted through the heart so starting in the right atrium there are some autorhythmic cells called the SA node that will automatically generate an action potential and it spreads all through the nearby cells so that all these cells become depolarized and then if they're able to in a healthy heart then eventually they get to another bunch of autorhythmic cells called the AV node it's at the bottom of the atrium where the ventricle joins together so it's sort of that juncture and together you take a purple highlighter this causes the entire so it's because it's spreading out this way like that all of the atria is now able to depolarize and that means it's going to contract in a second so this would be the P wave over here on what's called an ECG where if you hook electrodes up to someone's chest then you can see this electrical activity and this little bump right here represents depolarization of the atria that occurred at that time okay so then once the signal gets down to the ventricles there's the bundle of his switch kind of up in there then the bundle branches so the depolarization continues down what's called the septum the middle of the heart and then the Purkinje fibers are cells that then pass the signal up and the outside now the cool trick here is that by going up the outside like this when the muscle then contracts a moment later it will press the blood up and out the aorta and the pulmonary trunk and so it kind of squeezes from the bottom up okay so this is the QRS complex and that's right here sorry my dog was not happy with one of my cats he likes to be in charge of them uh one of them he thought one of them was getting out of line so all right so next I have this I think we're ready to move down so the heart is autorhythmic which means that it can be on its own I'll use my green pen here even if you cut off all of the nerves that go from the brain to the heart it would still be able to be on its own now it wouldn't have a lot of modulation it would probably always go around 75 beats a minute but it would be able to keep beating on its own just like certain neurons can in the brain but that's not what is happening in a healthy person that has nerves you have parasympathetic nerve fibers coming down the vagus nerve and they deliver a neurotransmitter called acetylcholine on to the SA node and that slows the heart down so it's going to make the electrical signal go through more slowly sympathetic nerves on the other hand coming from the spinal cord they deliver norepinephrine and that neurotransmitter will speed the heart up by making the sinoatrial node go faster and so you're going to get a faster electrical signal and then this whole process will be a little bit scrunched up in fact stur but there are also hormones in the bloodstream that can affect heart rate and the ones that you've probably heard of like epinephrine or also known as adrenaline and then maybe one you've possibly heard of thyroxine is the hormone that is able to speed up speed up the heart too because it's a metabolic hormone that makes makes the heart make more ATP and do more of it stuff ok so now let's go to the bottom here and we'll look at a blood vessel because the point of this page is to explain the cardiovascular system as succinctly as I can and I see that that breaks down into first of all knowing the parts of the heart and the blood flow through through the pulmonary circulation as well as the blood flow through the systemic circulation knowing which times the Bloods oxygenated which times the blood is deoxygenated then you should have a general understanding of how the conduction system works and lastly you should know what's in blood so blood is considered part of the cardiovascular system and we're going to start with the cells that are in blood so the formed elements of blood are the cells and then the watery components are part of the plasma so go ahead and take your pink highlighter and of course we have to start with red blood cells so red blood cells are also known as erythrocytes and will write their function in pink right here so a red recites whole function in life is to carry oxygen now they can do this because they are light and flexible they have no nucleus and they instead are crammed with a protein called hemoglobin and that's the protein that actually binds to the oxygen so this oxyhemoglobin bond and there's iron in each one of these hemoglobins hold on one second I need to pause this okay we're back in business my 9 year old it's a very very good Whistler but he I don't think realized he was doing a lot of whistling okay so the erythrocytes carry oxygen and the hemoglobin has iron in it that actually combined to the oxygen so then I'll come back to that in a second but next I want to look at leukocytes these are white blood cells and actually most of the white blood cells in your body are in your tissues I think maybe only like two or three percent of them are circulating in the blood so that's a small amount and they have the sole job of fighting infection in against invaders and they are able to leave the bloodstream and enter the tissues when they sense the chemical signature of a wound or an infection or something like that so they're able to leave the blood I'm sorry just a little bit okay so they're able to leave the blood at the wound or infection site okay now the last kind of formed element or cellular component in blood are thrombocytes I'll go ahead and highlight these in green so thrombocytes thrown both sides from both sides thrombocytes so really just platelets and so their whole goal in life is to help with blood clotting or sometimes we call this hemostasis but they can't do it on their just cell fragments that's why they're so tiny they're just little fragments of cells they can't do it on their own though they and that's good because you don't want these to start clumping and sticking together unless they need to so use your green highlighter again and we'll highlight their partner in crime so these represent chemicals in the plasma that are called clotting factors and these include enzymes proteins [Music] clotting in various small chemicals that can make platelets clump sorry clotting factors can make platelets clump okay then next up there are a lot of nutrients in the bloodstream so you've got glucose you've got fatty acids you've got amino acids and these are carried in the blood to the organs that need them next water about 90 percent of plasma is actually water so it's a very watery environment and then one of my favorites there are lots and lots of hormones in the blood whether it's insulin or growth hormone or thyroxine and these hormones travel in the blood until they reach their target tissue where they can bind to receptors there so you know just to give you a couple reminders got epinephrine thyroxine and maybe growth hormone lots of different hormones I have a video going on summarizing the endocrine system somewhere okay so then the antibodies are also circulating in the blood to keep you safe part of your immune functions next I'd like to color the endothelial cells green so your blood vessels are lined with cells called end a filial sells like all of these green and these are simple squamous epithelial cells so if you go over here endo means inside helium is like the blood vessel basically and if you remember back into your tissue work these are simple squamous epithelial cells which means that they're very flat and that is it why they're good at allowing exchange so go ahead and finish putting this green on here I'm both kind of sad and kind of excited that some of my pens are dying because that means that I have to spend more on pens but it also means I get to get new pens and I love to get new pens so then highlight this yellow tissue cell down here this could represent any cell in your body that the capillaries are bringing goodies to and then remember we were talking about the oxygen that's carried on the hemoglobin it's that's inside of the red blood cells so that oxygen is released from the red blood cell when it enters tissues that need it and then it simply diffuses through the simple squamous cell and then through the membrane of the tissue cell to bring oxygen into the cell with the same process carbon dioxide that's made by this cell in the process of cellular respiration is able to diffuse out into the bloodstream to be carried away any products that this tissue cell makes or other waste products can also be carried away at this point so next I will show you the smooth muscle not all blood vessels have a lot of smooth muscle capillaries don't have any so if this work capillary there would be no smooth muscle but if you imagine that this were an arterial man there would be a lot of smooth muscles because arterioles are the ones that constrict and dilate the most to regulate blood flow it's going to finish that and then put right here arterioles are hands-down the most important in this process to regulate blood flow and by doing that by regulating blood flow by limiting flow to an organ or increasing flow to an organ then what they do is they have the greatest impact on regulating blood pressure so arterioles will have a lot of smooth muscle for constricting and dilating arteries will have a lot of smooth muscle so the arteries would and they need it because the pressure is really high in them and otherwise they might actually rip and that's what an aneurysm is is when a blood vessel starts to kind of get a weakened a spot in its wall where the smooth muscle can't hold in again anymore and then veins will even have smooth muscle although they may be tend to not have as much and then remember they have valves as well so and then capillaries will have no let's just maybe put one point here so capillaries lack smooth muscle because if they had it then the stuff couldn't diffuse in and out like it needs to okay I think that we've covered most of what I wanted to do in this video I'm gonna zoom out on this one so I actually went faster than I thought I would which is great hope I didn't talk too terribly fast

Channel: susannaheinze

Views: 87,995

Rating: 4.9284863 out of 5

Keywords: cardiovascular system, conduction system of the heart, blood components, systemic and pulmonary circulation, blood vessels, arteries, capillaries, veins, arterioles, gas exchange, endothelial cells, plasma components, formed elements of blood, erythrocytes, blood pressure

Id: JDWeq0xg9nA

Length: 23min 1sec (1381 seconds)

Published: Mon Apr 22 2019