Circulatory and Respiratory Anatomy

hi. In this video, we're going to talk about gas exchange and circulation and look at the anatomy of the respiratory system and the cardiovascular system. Now the job of the respiratory system is to bring in gasses from the environment and specifically to take in 02 to the body. And it's going to Output Waste Co. Two from the body and we'll talk about in a second where these gasses air Coming from now, the circulatory system kind of has a hand in everything. It does a lot of stuff. It's involved in a lot of processes. We're just going to focus on its role in terms of gas exchange here. So while the circulatory system transports oxygen and carbon dioxide, it also transports nutrients from digestion hormones in the endocrine system and blood cells, uh, including white blood cells for the immune system. But we're not gonna focus on any of that. We're just gonna focus on the transport of these gasses. So the circulatory system is going to be responsible for delivering that oxygen to cells which they need for cellular respiration. It's also going to pick up and remove waste carbon dioxide, which is a byproduct of cellular respiration. So these gas is that you are breathing in and exhaling are, uh, needed for cellular respiration and waste from cellular respiration. Pretty incredible to think about what's coming in and out of our lungs as being involved in chemical reactions at the sub cellular level. Now, ventilation is going to be sort of the first step of this larger process of gas exchange gas exchange in circulation. Rather So ventilation is when air moves into, uh, you know, the Oregon of gas exchange like lungs, Uh, with some organisms. And we're not gonna cover this here will cover in a different lesson. They'll actually be taking in water and passing it through their gills. But for our purposes, we're gonna be using the example of taking air into the lungs. So then gas exchange is going to occur, which is when oxygen will diffuse. Uh um, you know, through the lung tissue basically into the bloodstream and carbon dioxide will diffuse out of the bloodstream and into the lungs. And this is of course, all gonna happen, as it says here, the respiratory tissue surface again, that's gonna be our lungs, right? That's our respiratory system. You know we don't have gills. No. Circulation is the transport of those diffused gasses, right? So oxygen is going to be transported to the tissues. Were it'll be used for cellular respiration? Right. It's the final Elektronik sector of the electron transport chain and CO. Two carbon dioxide is going to make its way into the circulatory system and from there to the lungs. And the CO two again is a byproduct of cellular respiration. Specifically, like Allah. Assists in the citric acid cycle, which you're going to be the components that breakdown glucose. So each of the carbons and glucose is going to be turned into a CO two and exhaled. So this is a very complicated process, and it involves two organ systems working in conjunction. We have the circulatory system, which sometimes is called the cardiovascular system, and we have the respiratory system rich. It is sometimes called the respiratory system. Just getting really it only has the one name. Now, the circulatory system and respiratory system are gonna function in conjunction, as you can see right here in this figure, and basically there's going to be two loops of circulation. What we call pulmonary circulation, which is when, uh, blood that needs oxygen. Blood that doesn't have oxygen goes from the heart into the lungs. So here's our heart. These are our lungs. So the de oxygenated blood, as it's called, is gonna go into the lungs. It's gonna pick up oxygen and make its way back into the heart full of oxygen now. So just for reference, when you see diagrams de oxygenated blood is often shown in blue and the oxygenated blood is shown in red. That's these colors represent. So once that oxygenated blood comes back into the heart, it's going to be pumped out into the bodies into the body on Lee One, uh, and in the body's tissues, the oxygen is going to be picked up, and the co two is going to be unloaded into the blood. And then that de oxygenated blood is going to make its way back to the heart. We call this systemic circulation, so pulmonary circulation takes de oxygenated blood to the lungs and brings it back to the heart. Systemic circulation takes oxygenated blood out into the body. Uh, gas is diffused there, and then it brings the D A. D oxygen gin ated blood back to the heart. And, of course, of course, I keep emphasizing this point. Those gasses are being used for and byproducts of cellular respiration. With that, let's flip the page.

vasculature is what carries the blood around the body. It's going to be lined with a special type of epithelial tissue we call endothelial IAM, and that's going to line the interior surface of these blood vessels. It actually also lines the interior surface of lymphatic vessels, but we'll talk about those a little later. Now there's basically, like three types of vasculature. You need to know their arteries, which are going to transport blood away from the heart. That's what determines an artery. The direction of blood flow is going away from the heart. Veins transport blood to the heart. Now the reason I emphasize the direction is because it's a common oversimplification that people to say, oh, veins, transport de oxygenated blood and arteries transport oxygenated blood. That's true in the case of systemic circulation. But don't forget, there's also pulmonary circulation. So in the systemic loop, arteries are carrying oxygenated blood. But in the pulmonary loop, the arteries carry de oxygenated blood. Remember, that's, uh, that's gonna be the part where the heart pumps the de oxygenated blood to the lungs. So arteries transporting that now arteries have these elastic walls and, you know, a lot of smooth muscle, and this allows them to change their diameter. Which is going to be important when we talk about blood pressure and as arteries start Thio branch and get smaller as they make their way to the tissues and ultimately to become Cap Hillary's. We call these branches arterials, and they have smooth muscle just like arteries, but they have a smaller diameter, so veins kind of like opposite scenario. Here, they're going to carry de oxygenated blood in the systemic loop, but in the pulmonary loop, they're gonna bring oxygenated blood from the lungs to the heart. Veins carry blood to the heart. When the blood's coming from belongs to the heart, it has oxygen. And because the naming of veins and arteries is about the direction of flow, you know, that's why veins air carrying oxygenated blood there. Now, veins are kind of different from arteries. They don't have all that Aziz much smooth muscle. They have some, but they can compensate for this because they actually will run through skeletal muscles. And we'll talk about the significance of that when we talk about blood pressure. Now, veins also have valves in them. Basically, it's going thio If you know, here's your vein. There is going to basically be thes flaps of tissue and they'll allow flow in one direction, but they'll prevent backflow. And the reason this is so important is because the pressure in veins is lower than in arteries arteries. They're gonna have a lot of pressure coming from the heart to keep the blood moving in the right direction. Veins, not so much because they're gonna be coming after the cap Ilary beds. So in order to ensure that the blood keeps flowing in the right direction, veins have these valves in them now, just like arteries branch into arterials before they, uh, you know, become even smaller and are considered capital areas. At that point, as capital Aries start to converge together, they form what are called venue ALS. So these air going to be like, you know, little veins that air going thio converged together and form veins like the main big veins and of course, venue ALS come from converging cap Hillary's. So what are capillaries? Thes are the, uh these I mean these air, the sites where the magic happens. Really? This is where gas exchanges going. Thio exchange of you know, many types is going to occur between blood and tissues, and they're really small. They're tiny, they actually their walls air Onley, one cell thick, and their diameter is about the size of a red blood cell. So they can basically, as you see here, let through like one red blood cell that time they're super thin. I'm sorry they have a super small diameter, and they're super thin. Thio allow for easy exchange. Now they're in tissues there, found as what are called capillary beds. Basically, it's like a a very branched network of capital Aries that's sort of diffuse through a tissue, and this helps maximize surface area in exchange. Now, because capital Aries don't have smooth muscle because they lack smooth muscle, they can't control blood flow like veins and arteries can. They can't constrict and dilate. However, there are what are called pre cap Ilary sphincters, basically ah, little sphincter muscles that will control blood flow into the capillary bed. So this is sort of a capillaries way of compensating and being able to have some control over blood flow. And again it's through these pre cap Larry sphincters that will control the blood that's moving into the capillary beds. So looking at our diagram here, tracing our loops again, we have the heart. And this here, remember, is, um, artery. Sorry, because it's going. It's blood is going away from the heart. So that is an artery, and this is a vain because it's going to the heart. These are arteries, and they're gonna branch, as you can see here and turn into arterials or be considered arterials. And when they get to the tissue, they're going thio become super branched and diffuse and form a cap Ilary bed. It sounds comfortable, doesn't it? Cap. Hillary bed could take a nap there. Now capillary beds are the capillaries in a capillary bed are going to converge and form vein. You ALS and those will converge and form veins. Those veins will lead back to the heart, so that is the basic rundown of the vasculature. With that, let's flip the page

the heart is a muscular organ that contracts to pump blood through the body, and it contracts just like you'd contract a muscle like the one in your arm. Of course, it's a different type of muscle, and we'll get into the details of that. But it's a similar idea now. The heart has various chambers in it, and these chambers air called atria and ventricles. The singular of Atria is atrium, if you're curious and ventricles would be ventricle, no special Latin, singular plural there. So the job of Atria is to receive blood from veins and ventricles, received blood from Atria and also pumped that blood into arteries and separating. Atria and ventricles are what are known as a trio ventricular valves. These are valves similar to, uh, you know, like what we saw in veins, and their job is to prevent backflow from the ventricle to the atrium. Blood needs to flow from the atrium into the ventricle, not the other way. In fact, if blood moves across the valve, this is a bad thing. It's known as a heart murmur, and usually it's due to some type of damage or infection in the valve. Now, between the right Atria. A right atrium and right ventricle is the try, Cuspide Valve. Don't worry about memorizing this name. And on the left between the left atria and left ventricle, we have the mitral valve again. You don't need to memorize this name. Now. There are also valves that prevent back flow from the ventricles to the arteries and these air called semi lunar valves. These again, they're gonna be on the There's gonna be one on the right and one on the left. The valve that separates the the right ventricle from the pulmonary artery is known as the pulmonary valve and the valve on the left that separates the left ventricle from the aorta is Aziz the aortic valve. Again. Don't worry about memorizing these names. Just know semi lunar valves and atrial ventricular valves just need to understand. So the basic idea behind what their purpose is now looking at the heart, you can see that in this diagram, right and left are backwards. That's going to be fairly typical because these diagrams air set up as if you are looking at someone's heart, right? Like you're facing them and looking at their heart. So everything is going to be married, right? That's why the right the stuff labeled right is technically on the left side of the page, and the stuff labeled left is on the right side of the page. So the three heart has various arteries and veins connected to it. That will lead Thio Pulmonary, uh, circulation and systemic circulation. The pulmonary artery is going to be part of the pulmonary loop, and it's going to deliver de oxygenated blood from the heart to the cap Ilary beds in the lungs. The pulmonary veins take that oxygenated blood from the cap. Larry beds and lungs bring it back to the heart. So this is all part of our pulmonary loop or Pullman pulmonary circulation. Whatever term is easier for you to remember. Now the aorta is going to deliver that oxygenated blood that's coming from the lungs to the tissues of the body and the vein that's going thio deliver de oxygenated blood from the cap, Ilary beds and the body tissues back to the heart. Uh, it's actually going to be two veins. Their plural name for the two of them is V. Nike Ave. It's kind of a mouthful. There basically broken down into what's called the superior vena cava and inferior vena cava. And it's not because one's better than the other. The names superior inferior come from the fact that one is found above the other. The superior one is located above the inferior one. So looking at our diagram here, let's just go ahead and trace the path of each loop of circulation. So de oxygenated blood is going to be delivered by the V. Nike. Avi Right here it's written singular, but because it doesn't really matter which one we're talking about for our purposes. Inferior, superior. Both gonna bring that de oxygenated blood in to the Remember, this is going to be the right side, so it's going to deliver it to the right atrium. The right atrium is going to move that blood into the right ventricle, and the right ventricle is going to send it through the pulmonary artery to the capillary beds in the lungs. From there, it will be theocracy. Gin ated blood will be delivered from by the pulmonary vein to the left atrium, which is going thio. Move the blood into the left ventricle and from the left ventricle it's going to be pumped through the aorta and delivered to the tissues, and that is going to be our pulmonary loop. And of course, our systemic loop takes us from the aorta all the way down through these tissues through all these cap Hillary beds Back up all these veins and delivers are de oxygenated blood from the vena cava to the right atrium. So these are our two circuits of, uh, blood circulation, and they basically each have a purpose to fill. The pulmonary circuit, as we've seen, is there. In order Thio oxygenate the blood right, absorb oxygen from the lungs and to get rid of the Waste Co two that gets picked up in the tissues. So the systemic circulation, the job of systemic circulation, is to deliver that oxygen to the tissues and to pick up that Waste CO two from cellular respiration and bring it to the lungs so that the body can get rid of it. So those are two circulatory loops. Let's flip the page and look at what's going on in the blood

blood is the fluid that moves through vasculature and is going to perform gas exchange with the tissues. It also plays a role in transporting nutrients, hormones and wastes. Now, blood is going to be made of three main components plasma white blood cells or Lucas sites and red blood cells or Aretha sites. Now, plasma is gonna make up the majority of blood. Let me just jump out of the way here so I can fill this in. So we have plasma. That's our main component. And it's like the liquidy portion of blood, which is why, in a test tube it's going thio be on the surface, right? It's gonna be less dense than the stuff below, so it's mostly made of water. It also has dissolved electrolytes, organic compounds and dissolved gas is now the smallest portion of blood is going to be made up of white blood cells. And they're also gonna be some of what are called him platelets. In here. Now, white blood cells are cells of the immune system that are gonna help fight and identify infections. We'll talk more about them in lesson on, uh, the immune system. Platelets are small cell fragments, and they're gonna play an important role in blood clotting, which is a wound response. So if there's damage to the vasculature, they will rapidly plug those holes. And they'll also you know, um, there will also be other factors and molecules that air recruited to help seal up that wound site. But the platelets offer this rapid response to very quickly clot and plug any holes now. Sometimes clots form when they shouldn't, and we call these type of clots thrombosis or a singular would be thrombosis. This is a clot that is going to form in a blood vessel and block flow. Not very good that can lead to some seriously bad news stuff. Now, red blood cells kind of get all the credit in terms of blood. That's what gives blood its color. And that's also going to be what carries theme oxygen. It's going to carry oxygen using this protein called hemoglobin, and it should be noted that red blood cells actually lack nuclei and organelles at maturity, and this is in part so that they can get packed as full as possible. With hemoglobin, you can see a picture of a red blood cell here thes air red blood cells. And they sort of have ah kind of dona t disk shape, this dark spot in the center that is like a depression in the red blood cell. You'll find it on both sides. They kind of have, like, a weird ring shape to them, and they're actually going to be produced in bone marrow. So are white blood cells, but their whole process of development is a bit more complicated. So red blood cells are gonna be produced in bone marrow. And actually, there's a hormone secreted by the kidney that will stimulate red red blood cell production. We call that erythropoetin. So red blood cells are Aretha sites, or with pro erythropoetin is a hormone that stimulates red blood cell production. And here you can see some white blood cells or Lucas sites. There's quite a variety of cells that fall under that category, and we'll talk more about those in lesson on the immune system. Now, red blood cells get their distinctive color due to what's known as a respiratory pigment. This is gonna be a molecule that increases the oxygen carrying capacity of blood, and the reason it gets its name the reason blood has that distinctive colors because it's actually going to change color from oxygen binding, which is kind of cool, because by looking at blood, you can tell based on the color color, whether it's oxygenated or de oxygenated. Now there are other respiratory pigments aside from hemoglobin, Um, but we're not really going to focus on those. We're gonna focus on hemoglobin, which is what's in our red blood cells. This is a protein that's actually made of four poly peptide sub units, which means that it has Quaternary structure and you can see those sub units right here there, each in different colors, so each one of those is a sub unit of hemoglobin. This whole thing is hemoglobin, and each one of those subunits contains what's called a heem. This is what's going to actually bind the oxygen. It's a co factor in the protein, and it contains what's called a poor foreign ring, and it's going to have iron in its boyfriend ring, and that iron is going to be reduced and oxidized in order to transport. Oh, too. So basically, Thio bind oxygen. That iron is going to be oxidized. And when a red blood cell wants to offload its oxygen. The iron is going to be reduced, meaning that oxygen will come off and move into the tissue. Now what's cool about this port friend ring and I think is worth mentioning. Just because it's a nice theme of biology is how nature tends to conserve structures. So this is a structure here being used for oxygen transport. We've seen something similar before in terms of photosynthesis. This here is also poor friend ring. It has magnesium at its center, so not iron, but same structure. You know what this is? This is chlorophyll. This is what plants use to absorb sunlight. Energy. So pretty cool stuff that that structure will appear in such radically different places for such radically different purposes. Just kind of an interesting little side note. No humans actually also have this other respiratory pigment and other animals or other mammals due to it's called myoglobin. And this is the primary pigment of skeletal muscles. And actually it's on Lee going to contain one heem instead of the four he seems that we see in hemoglobin and it binds oxygen tighter. Then hemoglobin does, and this is going to be super important. When we talk about oxygen dissociation, curves and oxygen binding, my global plays a very important role. For muscles, however, it's it's a kind of sophisticated, and we'll get to it later when we talk about thief physiology of hemoglobin, an oxygen binding now, last thing I want to mention is a disease that results from abnormal chema globe hemoglobin. It's called sickle cell disease, and basically what happens is the hemoglobin proteins have a mutation, and it causes them to aggregate in red blood cells. And so this is going to result in a distorted shape, and it's going to inhibit their functions. So this is a nice, normal, healthy red blood cell, and this is a sickle cell. You can see very clearly that you know this. The shape of the cell is all wrong, and sickle cell disease can be life threatening. However. Interestingly, it's stuck around in the population because it's controlled in a single gene locus and essentially, um, people who are hetero zegas for this gene, meaning you know, they have the dominant and recessive Leal's actually do better against against malaria than people who have the dominant forms of the illegals that would, you know, lead to these nice, healthy red blood cells. So the reason that recessive mutant alil, which when you have two of them, you know you'll get thes sickle cells. The reason that stuck around the population is again because of malaria. It actually helps confer resistance to malaria. So even though sickle cell disease can kill you, hetero zygotes are at an advantage when it comes to you dealing with malaria. With that, let's flip the page.

the throat at the back of the mouth is known as the pharynx, and it's a shared passageway for food, air and water. Which is why I'm sure we've all had the nasty experience of having Cem food. Or maybe some water go down our wind pipe and the wind pipe is the trachea. This is what brings air from the pharynx to the lungs, and it's actually supported by these rings of cartilage that are kind of C shaped. Basically, if you have the tube, the ring of cartilage kind of runs around it. Like such now. The beginning of the trachea is called the larynx, and this is sometimes called like the voice box or the vocal cords, because it contains what are known as the vocal folds, which is how I'm talking to you right now. Now the trachea is going to branch when it gets to the lungs and these two branches air known as the primary bronc. I now bronc I our branches from the primary bronchi I So this primary bronchi air gonna branch off into many smaller bronc I that will diffuse throughout the lungs, and they're going to be supported by cartilage similarly to the trachea. Now, the thing about, uh, thes bronc eyes, they they're gonna be getting smaller and smaller. These it's, you know, think of it like a tree. There's going to be, you know, thick branches, and then smaller and smaller branches will come off of that. The smallest branches of these bronchi bronc I are called bronchial walls, kind of like arteries arterials or veins, and Daniel's got bronc I and bronchi ALS. So these are the smallest branches, and these guys are not supported by cartilage. They're supported by smooth muscle, and this means they can collapse, which is a bad thing. Now the lungs are the organs of respiration in humans and, um, you know, mammals. So their job is going to be to inhale air and absorb that oxygen and exhale the waste carbon dioxide. Now, the ends of these bronchi ALS are known as Alvy lie. They kind of looked like Bunches of grapes. Um and this is where the gas exchange between air and blood is going to occur. This is thief thin layer of respiratory tissue that's going thio. You know, actors theme the act as thedetroitbureau for surface and not only is this a thin layer? It's also Aquarius, and it's going to be that acquis interface between theme air and the tissue that is going to be the surface that the gas is passed through. And they're going to make their way to these cap Hillary beds that surround DLV lie. So here you can see the Alvey lie, these little pink sacks that kind of looked like Bunches of grapes. And they're surrounded by cap Ilary beds. As you can see in this particular image right here, I said that they have a new acquis layer. Now, remember that water has surface tension. So in order to avoid these Alvey lie collapsing. Remember, bronchi ALS can collapse. These Alvey lie are even more prone to collapsing where they would be. Except they have this stuff called surfactant, which is a mix of phosphor lipids and proteins that air produced by some l've Eli and what they do is reduce surface tension. So they're gonna help prevent the Alvey lie from collapsing, and we need the Alvey lie to not collapse so that gas exchange can keep occurring at that surface of the respiratory tissue. So that is the basic anatomy of the respiratory system. However, there's one important piece to the puzzle here, and it's this muscle called the diaphragm. It's kind of like a sheet of muscle that runs through the middle of your chest, and it separates the top half of your torso from the bottom half, and we call that top half the thoracic cavity. Like the area. All the area in there is the thoracic cavity. You know, that's where your lungs and heart are gonna be located, for example, and the bottom half underneath the diaphragm is called the abdominal cavity cavity, and that's like where your guts are, right, your intestines and that sort of stuff. So the diaphragm runs across, and it's this sheet of muscle, and it's going to be what's responsible for pulling air into the lungs. It's going to contract and and pull down, and this is going to create negative pressure that pulls air into the lungs will talk about the physiology of this later in a different lesson. But those are the main components of the respiratory system the, uh, the trachea, the bronchi, the lungs and the veal. I is that important place where gas exchange is going to happen. With that, let's flip the page

the lymphatic system in a similar manner to the circulatory system is a network of vessels. However, these are lymphatic vessels instead of blood vessels, and they carry lymph rather than blood. Now the lymphatic system picks up what's called interstitial fluid. It actually drains plasma from the interstitial fluid, and the interstitial fluid is basically the fluid that surrounds and bathes the cells in our body. So it's gonna pick up fluid from outside of cells, and the lymphatic system is going to bring this fluid toward the heart now. This fluid, as we said, is lymph. It's a clear fluid, and it forms again from interstitial fluid entering lymphatic ducts. It's going to be filtered through what's known as lymph nodes, which are organs of the lymphatic system found all over the body and play a super critical role to the immune system. In addition, the lymphatic system includes the organs, the spleen and the thymus. Their roles air also going thio have to do with the immune system. So in terms of circulation, the lymphatic systems main job is basically to drain any excess plasma from the interstitial fluid and bring it, bring it towards the heart it will get filtered along the way. Make sure there's no pathogens in there that are going to get into your bloodstream. And then it's gonna actually add that plasma back into the bloodstream. And you can see here how the lymphatic vessels and the vasculature our associate it very closely and how they can, um, exchange fluids. That's all I have for this video. I'll see you guys next time.