okay so this chapter is the circulatory system otherwise known as the cardiovascular system and so this includes the heart which I always think is going to be a pretty short chapter but it also includes all the blood vessels as well which makes it a pretty long one so the circulatory system or the cardiovascular system is all about transport so this is like the amazon.com of your body it's all about sending stuff to the cells and picking up their waste so cells obviously need stuff they're like little factories so they're gonna need oxygen they're gonna need water they're gonna need minerals and they're gonna need sugar of course so the sugar and oxygen remember to do cellular respiration which we all love that's how we make our ATP it's how we make our cell energy and so why this while the cells are they're functioning and doing their thing they're gonna make a lot of waste and so the waste predominantly is the carbon dioxide we got to get that out of there but also hydrogen and urea and ammonia from breaking down proteins so the point is this guy is all about getting the good stuff to yourselves and take the bad stuff away so the cardiovascular system allows for a two-way exchange between your body and between the outside environment so we have the lungs the lungs of course we'll be getting to when we do the respiratory system is all about getting oxygen from the air and then sending that co2 back out so in this case the environment is the air that we breathe and the body tissues are the cells within our body and in our bloodstream the GI tract we also see exchange between this and the blood because the gastrointestinal tract your digestive system is where you absorb all the nutrients from the cheeseburgers that you eat and you bring that into the lumen of your intestine so the word lumen just means space so if you think of the intestine like a paper towel tube how you can hold up a paper towel tube and look through it that Center space is the lumen so in this case the environment is the lumen of our intestine that's where the food would be and we're bringing that into our body tissues the blood or the lymphatic system so the circulatory system or cardiovascular system consists of the heart and the blood vessels so like I said that's what makes this chapter really long is we will also have to identify the vessels in lap but we're going to be talking about how blood vessels work in lecture so we like to talk about the overall function of every system before we get started so that is our goal so homeostasis is the ultimate goal of every organ system except for reproduction and so the cardiovascular system is very powerful for homeostasis as well and some things you may not think about like it's all about sending out glucose to maintain glucose levels in your cells and calcium to make sure the calcium is getting to the to the bones and other cells that need it but also the blood the blood flow maintains your pH and your body temperature because if you think about body temperature and blood it's almost like ocean currents how the Sun will cook one side of the earth all day long well we need to distribute that heat so the cardiovascular system does the same thing for your body if you're on a treadmill which I try to avoid and your lower body is really doing a lot of work you're gonna be generating a lot of heat well you don't want your body to cook from the waist down while from the waist up you freeze to death so even though most of the heat is being generated in your lower body because of the way the blood flows it helps distribute the heat so we will be doing a lot in lab with heart structure so if you've been to this lab already you've kind of heard this and it'll be a review otherwise it might be brand new so the heart structure is about the size of your fist so it's about 14 centimeters long and 9 centimeters wide you don't have to know those numbers because of course everybody's different it's located in the mediastinum which is the space between your lungs behind the sternum and the bottom of the heart which we call the apex actually rests on the diaphragm so that it's made up of four chambers we have two atria which are the top chambers that are a lot smaller and two ventricles the harp has several coverings we did this in a mp1 but we have slept since then so I like this picture I stole it from the internet and I like it because it's nice and simple it shows the red heart muscle and then other various colors so we have the outermost layer here which is in that look kind of bluish color which is talking about the fibrous pericardium so peri means around like a perimeter fence goes around your yard cardio means heart the fibrous layer is the one layer we didn't talk about Nate a mp1 so I think of this like in winter time you may wear one of those big wool overcoats so this is for protection right an Illinois winter it's kind of cold well this fibrous layer protects the heart but it's very thick it's got a lot of collagen in it which is that protein and so it can't be touching the heart directly just like you really wouldn't want a wool overcoat to be touching your skin directly because it would be very irritating so this guy is the furthest out layer of the heart he's really facing the cavity of your heart so this guy protects your heart anchors keeps it in place because if you've ever seen the heartbeat it beats like crazy if you've ever watched a surgery that guy's jumping around in there we want to make sure he stays in place and also prevents overfilling it's like we we don't want no matter how hard our heart is pumping we don't want it to like swell up where it could potentially burst so this kind of the fibrous pericardium kind of gives it like a limitation so this is the outer fibrous layer the inner layer is what we call the parietal and visceral layers of the pericardium so this guy we have the visceral pericardium if you look at this picture it's in yellow there this is the layer that's directly touching the heart so I like to think of it like a like saran wrap around your heart I like to think of it like um your underwear so your underwear are probably your most delicate layer I would assume I don't think you probably have on plywood underwear but I don't know what you kids are into but the point is we can't have like something like wool or steel rubbing against our boy and girl parts all day I mean think of the chafing so this is delicate tissue the heart's delicate tissue as well so the membrane that touches your organs a mp1 we called it the visceral layer because viscera means organs and in the second word is what organs are we touching so in this case we're touching the heart so the visceral pericardium is the layer touching the heart then you have the parietal layer which i think of is like a sweater so you have your underwear and then you have the sweater so the sweater is a little bit thicker because it's not as in direct contact of your skin as your underwear is and so it's a little further out and the space between like their space between your sweater and your skin usually it's filled with air the space here if you look at this picture is filled with it's the pericardial cavity which is filled with pericardial fluid generically we call this serous fluid so in your lab manual I think it's on page 10 they go through those serous membranes again if you don't remember them and we will talk about them in lab so this pericardial fluid is basically going to function like the oil in your car friction is the devil when parts rub together especially organs they could blister they could bleed they could get inflamed and so we want to make sure that doesn't happen obviously the heart is in there jumping around a hundred thousand times a day we want to make sure just like the oil in your car we want to make sure the Pistons or whatever in your car don't get overheated and cause your engine to explode we want to make sure the heart doesn't do that either so we have the fibrous pericardium which is the outermost layer like a wool overcoat then we have two additional layers we have that make up the serous pericardium which is what we did in a mp1 the parietal layer that lines kind of the surface of the chest cavity and then the visceral layer which lines the surface of the heart it is also called epicardium because epi means on and cardio means heart so you can use that word as well it seems like a reoccurring theme of this class where you have a lot of structures like the pericardium that are there to protect the heart but when things are going wrong it actually ends up causing more damage like an A&P one when we talked about meningitis the meninges around the brain are there to protect the brain but when they get inflamed they almost cause more damage so inflammation of the SAC around the heart inflammation of the pericardium is called pericarditis this decreases the Feres fluid which is again just pericardial fluid it decreases the production so if you ever don't put oil in your car if you ever forget to put oil in your car things will start kind of knocking you kind of hear this knocking sound well that's because metal is starting to rub on metal and then it overheats your engine and your engine could blow up I don't know much about cars but I know that's bad so it's the same thing here we don't want the heart to start rubbing because if the heart's rubbing then it's more likely to get inflamed to get angry can't do its job so this could this could be very dangerous when there's not enough fluid in there just like not enough oil in your car the good news is you can diagnose it pretty easily with a stethoscope it'll sound like a muffled sound because you're getting this rub it kind of rubbing in there so at least they can do something about it opposite this is when you have too much fluid so I think that's again the reoccurring theme of this class is you have normal and then you have when it's too much or too little so this is when you get way too much fluid in that space well because of your sternum there's nowhere for that pressure to go so it eventually starts pushing on the heart again they can go in and treat this with a needle to draw off that excess fluid because otherwise the heart will get squeezed so the layers of the heart wall so we have the epicardium which is the outer so that's just directly touching the heart okay and so it's also called the visceral pericardium so you can use either word for the lab practical especially myocardium is the middle layer of the heart itself so middle and Myo is how I always remembered it we also had my o and AM P 1 meaning muscle and then endocardium is the innermost layer and so what I like to do is just pretend if you're looking inside the heart and you can see those four chambers just pretend those four chambers are lined with saran wrap because it's a single level it's a single cell layer it's not very thick it's kind of like epicardium like saran wrap on the outside of the heart endocardium lines the four chambers so epicardium like I said visceral pericardium is a perfectly fine dancer as well it is made of connective tissue with epithelium blood vessels lymphatics and nerves so obviously we need blood to feed this tissue keep it alive we need lymphatics which is your immune system to keep it healthy and we have nerves to control it the myocardium is by far the thickest layer so in lab I will or I have depending on where you're at point out how thick that myocardium is especially on the left side so that's something you always want to notice when you open up a heart is you should be able to immediately identify left from right based on the thickness of that heart muscle the left side is so much thicker because that's gonna pump blood to the entire body so it needs to be really beasty so this layer has a huge supply of vasculature which is blood vessels because this guy is going to be using tons and tons of ATP he needs to make sure he's getting lots of oxygen and sugar there's also nerves there's also lymphatics to keep the tissue healthy endocardium so like I said again kind of picture saran wrap lining the inner the inner chambers of the heart but this was something that we kind of saw last semester the simple squamous epithelium if you remember that so it's just one layer of those little those little squash cells okay and some connective tissue so inside this endocardial layer you have elastin and collagen proteins we did see last semester college and remember is the thick protein ropes when you pull on those they don't stretch and elastin is like a protein jumper like jump rope or what are those called where they stretch and kind of snap back so collagen is really really really really tough it's like a rope and elastin is more like a bungee cord that's the word I was looking for that's really stretchy so we want both right we want the inside of our heart as our heart beats to stretch and be strong which is from the collagen but also to snap back into place which is the elastin so this lines all the Chamber's and covers the heart valves another important thing is it's continuous with the endothelial lining of your blood vessels so the blood vessels are lined with endothelium simple squamous epithelium and the heart is lined with NO core endocardium which is simple squamous epithelium and so the fact that it's continuous means that when the blood vessels are going into the heart that layer merges so it's not like in your house when you have two pipes that come together and you have to hook them together plumbers will try to make that really really smooth because they don't want any place for like hair or toothpaste or toilet paper to get stuck which could lead to a clog but plumbers will tell you that's one of the hardest things is to make sure there's a seamless transition between a pipe in your house say and the sewer pipe outside that's a place that things usually get clogged up well this doesn't happen in the human body which is kind of brilliant the fact that the layer inside the blood vessel merges directly into the layer inside the heart so there's no place for things to get stuck which is good so the fibrous skeleton so in this picture here it's kind of showing that fibrous wool coat that's on the outside of this and it's basically just illustrating especially the rings around your heart valves that the fibrous skeleton just provides a place for things to attach because it's a nice tough layer otherwise if you try to attach things to the heart muscle directly then things would get likely to be torn we also want to make sure those valves don't over dilate the blood is flying through there we want to make sure it kind of has a frame around it to make sure those guys don't pop we'll also see how the fibrous skeleton separates what's called atrial sanctum from ventricular sync diem which basically means if you're in sync with someone you're on the same page right you're doing the same thing you're on the same rhythm well we need the atria to squeeze at the same time and then the ventricles to squeeze at the same time and the fibrous skeleton helps with that which will see much later on