Understanding Circulation and Blood Vessels

hi everybody dr mike here in this video we're taking a look at what you need to know about blood circulation and blood vessels to begin with we need to understand the fact that we have a circulatory system which is carrying blood and it's carrying blood around the body delivering this blood to the tissues and also taking this blood away from the tissues of the body the question we need to ask ourselves is why well there's a couple of reasons why we have a circulation first reason is that it needs to deliver stuff the other reason is that it needs to remove stuff again what are we delivering what are we removing well one of the things that we are delivering is nutrients nutrients in the form of glucose and amino acids and fats for example what are we taking away well we're going to be taking away waste right and this waste can include things like ammonia and uric acid and a whole multitude of things that we don't or no longer require it's not just nutrients though it's also gases that we're delivering so we're delivering things like oxygen and we're removing things like carbon dioxide which is the exhaust of the cells we're also delivering things like hormones as well so we know now what the circulatory system does it's delivering stuff and taking stuff away and it actually does this through two separate circulations we have what we call a systemic circulation which is where we go from the left hand side of the heart to deliver all these things to the tissues of the body this is called like i said the systemic circulation sometimes it's referred to as the peripheral circulation and then we also have what we call the pulmonary circulation so this is going to be the right hand side of the heart going to the lung so the pulmonary circulation so we've got these two different circulations now a couple of other things this blood that we're pushing through to deliver these nutrients oxygen gases hormones and to take various things away we have around about five liters of this blood in our body so it depends on your body size and your sex for example but generally speaking seven percent of your body weight is the volume of blood in your body so for me that's around about five liters now this five liters is going to be distributed to various tissues of your body so at rest what you're going to find is that at any one moment this heart is going to be contracting relaxing contracting relaxing and if you calculate how much it contracts and relax over one minute you'll find that it ends up pumping out around about five liters of blood so we do have five liters in our entire circulation and in the span of one minute five liters at rest actually gets pumped out to go to the tissues of your body of this five liters what you're going to find is that five percent goes to the coronary arteries to feed the heart itself 15 goes to the brain 25 percent goes to our gut 20 percent goes to the kidneys 20 percent goes to the muscles and 5 goes to our skin the remaining 10 goes to other tissues of the body now as we leave the heart i want to look at the different vessels that are involved so there's a whole range of different vessels that we need to go through so what we're going to find from the left hand side of the heart the blood vessels that leave the heart in actual fact any time a vessel moves away from the heart think of the a in a way anytime it moves away it's going to be an artery so even if it's the left or right hand side we know that all the vessels that leave the heart leave from the ventricles so this is leaving the heart this is leaving the heart they're moving away from the heart to go to specific tissues if it's the left hand side it's the tissues of the body if it's the right hand side it's the lungs this vessel is called an artery so arteries move away from the heart so here we've got an artery what do you need to know about arteries well arteries have huge amounts of elastic tissue why is this important think about this right this left-hand side of the heart it's getting oxygenated blood from the lungs it fills up and then it contracts to pump that blood out now it's going to be delivering this oxygenated and nutrient-rich blood to all the tissues of the body from the top of the head so the brain down to the tip of my toes it needs to generate force or it needs to generate pressure which means that the highest amount of pressure found in our vessels will be found in our arteries because that's the first vessel that leaves the heart it's going to be under the highest amount of pressure which means that heart contracts the blood goes out that artery needs to stretch but most importantly not just stretch that artery needs to snap back so it needs huge amounts of elastic tissue present not just so it can stretch but more importantly again so it can snap back so arteries are elastic based vessels so here i want to highlight the different vessels that we're going to be talking about and like i said here we've got arteries elastic vessels now the arteries you'll find start to branch like a tree branch and branch a branch and you can see them branching here these branches are obviously going to be smaller than arteries and what you'll find is that the terminal aspect of the artery so right at the very end after all these branches the smallest arteries that you'll find are called arterioles so these here are arterioles let's label them now what do we know about arterioles well they're not really elastic like the big arteries they have lots of smooth muscle lots of smooth muscles so you can see all this smooth muscle wrapped around these arterioles why is this important for us to know that there's smooth muscles around arterials well the tissues of our body need to be fed oxygen and nutrients some need to be fed more so than others and the demands of the body can change over time and in response to certain environments so we need a way to redirect and deliver blood in different quantities and different amounts under different pressures depending on the environment that we're under let's just say i need to start exercising i need to deliver more oxygen and nutrients to my muscles compared to other tissues of my body and the way that we do that is through these arterioles specifically the smooth muscle the smooth muscle is going to respond to the nervous system such as the autonomic nervous system more specifically the sympathetic nervous system sends noradrenaline down to tell them to constrict right but it can also not tell it to constrict and tells it to relax this obviously redirects blood there's also local effects that can happen right so if this tissue is really hungry for oxygen it's going to produce high amounts of carbon dioxide and it's going to have low amounts of oxygen and it's going to have a whole bunch of metabolic byproducts just accumulating all of these are local signals that can tell the blood vessel to dilate and open up to bring more blood in that in conjunction to other vessels constricting is going to redirect blood so you're going to have blood backing up if it constricts and if it dilates like here at the muscle that blood will then be under a higher pressure to deliver the muscle or deliver the oxygen and nutrients to the muscle so the smooth muscle that's present within our arterials and let's write this down so we wrote elastic here let's write muscle here for arterioles it's really important they're also known as resistance vessels okay so arteries are known as elastic vessels our arterioles like these two here are known as resistance vessels brilliant at the end of these arterials we then hit the capillary beds this is the site of exchange this is where where we're going to deliver oxygen we're going to deliver nutrients and we're going to receive all of the metabolic byproducts and waste and gases and so forth so here is the capillary bed and they are the site of exchange and i'm just going to label this like that the site of exchange on the other end of capillaries we're going to have predominantly deoxygenated or less oxygenated blood with fewer nutrients and higher levels of waste and this blood gets collected in venules so this is the first part here venules and then ultimately drain into veins so we have venules and veins and what you need to know about venules and veins is that they have a huge capacity to hold blood huge capacity so if i were to pour a whole bunch of fluid or blood or whatever it may be into veins they fill up like a balloon now you might be thinking isn't that similar to the arteries that's under high pressure so that stretches too but because of all the elastic tissue in the arteries they can snap back but veins are a little bit different they don't have all this elastic tissue but they stretch because they're very thin and they've got a little bit of muscle so they can contract if they need to but because they can stretch so much and hold so much blood they're known as capacitance vessels capacitance vessels so here we've got venules and veins and again they're known as capacitance vessels and just to reiterate the point of capacitance vessels is they hold huge amounts of blood in actual fact the veins and venules are the body's major reservoir for blood so even though i said that of the five liters that it gets that gets ejected from the heart every single minute this is how it's broken up to the tissues of the body where is this five liters of blood sitting at any one moment so what we're going to find is this seven percent of the five liters of our blood is going to be in any one moment found in our heart then what you're going to find is that around about 13 percent is going to be found in the arteries around about seven percent is going to be found in the arterioles and capillaries so both arterials and capillaries we're going to have seven percent we have 64 of the blood in our veins and venule 64 and then we have 9 in our pulmonary circulation so have a look at that we've got seven percent of our blood in any one moment in our heart thirteen percent in our arteries seven percent in our arterioles and capillary beds sixty-four percent in our veins and venules and nine percent in our pulmonary circulation most of our blood is sitting in our veins and venules 64 this is important because it is our reservoir again they're capacitance vessels they have the capacity to hold all this blood it's a reservoir if we need to bring more blood back to the heart we can do so because there's a little bit of smooth muscle in our veins that we can squeeze and if we squeeze it we can deliver this blood back into our heart and remember the more blood we deliver into our heart means the more blood that we can eject out of our heart so what you can find is that arteries are elastic arterioles have smooth muscle they're resistance vessels capillaries are the site of exchange venules and veins while they're very thin walled and they can stretch a huge amount they're called capacitance vessels and they hold most of the reservoir of our body's blood so this is a quick summary of the circulation of our blood and also the various vessels of our circulatory system hi everyone dr mike here if you enjoyed this video please hit like and subscribe we've got hundreds of others just like this if you want to contact us please do so on social media we are on instagram twitter and tick tock at dr mike todorovich at d-r-m-i-k-e-t-o-d-o-r-o-v-i-c speak to you soon

Channel: Dr Matt & Dr Mike

Views: 37,037

Keywords: circulation, explain, understand, blood, vessels, arteries, artery, arterioles, arteriole, muscle, resistance, capacitance, elastic, tunica, intima, media, externa, cardiovascular, system, heart, distribution

Id: S8IMBEYhtUU

Length: 13min 36sec (816 seconds)

Published: Thu Aug 11 2022