Blood Vessel Characteristics

blood 

vessel characteristics 

What I want to do is I want to go over a bunch of 

different vessels talk about their structure their function a little bit about their histology what some you know special characteristics about them so the first thing I want to do is I want to talk about the different types of vessels so it's kind of let's go over them we're gonna kind of label them and then we're gonna try to hit each one individually so the first one I want to talk about within the artery department is we're gonna talk about our elastic conducting arteries right so this is the one that we're going to talk about here the elastic conducting arteries the second one I want to talk about is going to be called the muscular distributing arteries then I want to talk about the arterioles and then we're gonna discuss the different types of capillaries very briefly.

We'll go into them in more 

detail microcirculation and then we're gonna talk briefly about venules not too much again and we're gonna spend more time on our veins alright so the ones that we're gonna spend a lot of time on in this video is elastic the muscular distributing we'll talk a little bit about arterioles and we're gonna talk about a lot about veins alright so first things first let's talk about elastic conducting arteries so if we take elastic conducting arteries these arteries are usually an example of larger vessels right 

So for example let's say I take here's my left 

atrium and I got left ventricle then I got the aorta right, for example, the aorta is one of the prime examples of an elastic conducting artery right and then obviously think about the branches of that you got the brachiocephalic which gives way to the right so then after that you'll get the right common carotid in the right subclavian right so even these guys are gonna be high-pressure systems they're able to take on a lot and I mean a lot of pressure but if you think about the aorta the thoracic and abdominal they brachiocephalic artery those are gonna be higher pressure systems that have to be able to stretch and take on that high amounts of systolic pressure right so they have to be able to stretch and then recoil so elastic conducting arteries are again good examples of like the aorta ascending aortic arch thoracic abdominal and the brachial cephalic right those are just a couple examples and then if you think about them they have a pretty big diameter their diameter ranges at about 1 to 1.5 centimeters in diameter right.

So that's the elastic conducting 

arteries the muscular distributing arteries if you think about it let's see here I have the aorta let's say we go down you have the diaphragm here let's say here's the diaphragm so then we go down into the abdominal aorta, you know of the abdominal aorta, you have a bunch of different arteries, one can come up give way to the super renal artery one could be the renal artery and we could just keep going one could be the gonadal and you see superior mesenteric so on and so forthright so this one could go and supply the adrenal gland this one can go and supply the kidney but they're basically, arteries that are delivering blood to a specific organ right so these ones right here that are taking blood and delivering it to the tissues these ones are going to be called your muscular distributing arteries right so for example the renal artery the super renal artery if you think about another one there's the inferior phrenic artery and we could just keep going on and on and on all right, it supplies the diaphragm but the muscular distributing arteries again they're gonna be high pressure systems they're gonna have a stream Li thick tunica media very very thick tunica media and again these guys diameter because of the thick tunic immediate changes and it goes to about six millimeters okay arterioles arterioles.

let's say on 

the kidney and I blow that upright so if I look let's say here I have an arteriole right the arterioles are gonna be the ones that are feeding a capillary bed so let's imagine this is a capillary bed here and then let's say off of this obviously, you have your true capillaries right so let's say here are our true capillaries coming off of our vascular Shawn here so again these arterioles are the ones that are feeding it right they're the ones that are feeding this capillary bed right here where arterioles are very very small vessels again very very small vessels they pry range in diameter about 35 microns so about 35 micrometers in diameter so they're pretty small diameter right they're not very big and so with these guys what's really really important about arterioles.

One of the most important things about arterioles 

is that if you remember they have a nice little smooth muscle layer here wrapping around this actual med arteriole and it could be very very important and that can may actually be right around the bed is actually there more specifically right around the bed of the cat the capillaries the true capillaries these guys are called precapillary shrinkers and they're smooth muscle and basically whenever the sympathetic nervous system innervates them it causes them to constrict right so one of the biggest things about arterioles is that they are high resistance vessels they develop the most resistance to blood flow, okay so that's one of the big things to remember about our tiers is that they're extremely high resistant vessels, okay and then if you get into the last one here for the arterial side, it's going to be the capillaries. 

The capillaries are obviously extremely small they range 

in diameter probably right around eight to about 10 micrometers in diameter right so if you look at a capillary here 

that capillary 

I take a piece of this Kapler and I zoom out on that now so if I look at this capillary now you have three types of capillaries and I'm not going to mention too much about them right now like I said we'll talk about them more in microcirculation but the inner lining of the capillary has that Tunica intima or Tunica internal lining right with the simple squamous epithelial cells right and then it has a tiny little basement membrane here just a tiny little basement membrane right and then on top of that it obviously can have large intercellular kanessa my intercellular cleft sore some fenestration pores and it might even have tight junctions depending upon what type of capillary it is and another thing that has depending upon where it is is it can even have these little like types of smooth muscle cells called peri.

Sites all right like I said we'll go 

into more detail on this and then one thing wrapping all the way around that is a basal lamina okay it's a basal lamina which is like a connective tissue layer thin little connective tissue layer right that's called a basal lamina but basically, what capillaries are designed to do is they're designed for exchange gas exchange nutrient exchange hormone exchange waste exchange but they're basically exchange vessels so what's the significance of capillaries they're designed to be exchange vessels like I said we're gonna talk about exactly the mechanisms of exchange when we get into the bulk flow and microcirculation all right but for right now that's what I just wanted to focus on so again elastic conducting arteries about 1 to 1.5 centimeters extremely high-pressure systems they have to be able to be extremely elastic in recoil muscular distributing about 6 millimeters in diameter and these are gonna be the ones.

That is delivering blood specifically 

to that organ, for example, the renal artery or the super renal artery or the inferior phrenic artery is okay and they're gonna be extremely thick tunica media then we can get into the arterioles which are about 35 micrometers in diameter and again they have these pre capillary fingers these smooth muscle layers right that can control the resistance and they are the resistance vessels they're the highest amount of resistance is and then again these true capillaries their exchange vessels and again they consist of a Tunica Interna a tiny little layer of a subendothelial layer and then after that it has these tiny little parasites depending upon the capillaries and then basal lamina routes on that right venules I'm not gonna spend too much time about vanishes again we're gonna go over that whenever you're into microcirculation but if you look here for right now this is an arteriole it's called your terminal arteriole this is your meta arteriole this is your your capillary bed right here and then this part right here at the end of the capillary but it's called the postcapillary van

That drains into this 

eventually, this terminal goes into this vein you'll hear this post-capillary manual so we go post-capillary manual and then eventually it'll form large veins so I'm not going to talk too much about venules just for right now know that they're basically going to be the part that the initial parts after the capillary bed and their diameter is about 20 micrometers in diameter right all right pains means is the ones that I really want to spend some time on in this what's important about veins 

they have a pretty 

big diameter also they're about five millimeters in diameter on average and what's important about being so here's

What I want to spend some time on with 

veins because veins are extremely interesting right we knew that arteries are high-pressure systems right they're designed to be able to distribute blood to various parts of the body for your systemic circuits right and so in depending upon your coronary circuit you're pulmonary circuit but they're extremely high pressure systems venous blood is not high pressure systems they're designed to be lower pressure systems these pressures usually only get to about five to ten millimeters of mercury so on average so that's pretty low pressure system it's an extremely low pressure system what's so important about veins that I want to mention is if you look at veins some of the characteristics of veins right veins they have a very thin tunica media and I'm going to get into these these tunics here in a second very thin tunica media all right so they have a huge lumen they have a larger lumen okay larger lumen and they're described to be capacitance vessels or reservoirs of blood so they're kind of designed to be what's called capacitance vessels in other words veins account for about seventy percent of our total blood volume.

volume and anyone instant so at anyone the 

instant they account for about seventy percent of your total blood volume so they hold a decent amount of blood here's the problem though if you think about it let's say I draw here I draw the right side of the heart so let's say here's our superior vena cava the right atrium and then let's say here's your inferior vena cava and then there's your I ventricle and the pulmonary sorry or the pulmonary arteries right so if you think about this what's important to know is is that veins or again are not very high-pressure systems so how do we get the blood to get back up against gravity without having a not having that much muscle if you don't have that much muscle with inside the vessel you're gonna have to cut develop a couple different types of adaptations right so that's what the veins do so now what I'm going to do is I'm going to zoom in on a vein I'm going to show a couple specialties of a vein so again you have your Tunica Interna right such as these endothelial cell lining so what's important is these Tunica interna.

they kind of fold inwards and form these 

little valves all right so let's say here's again another folding of the Tunica Interna I'm gonna develop these valves here and they're basically just again internal folds of the Tunica Interna now look at what can happen here if the blood is pushed up this way I'll explain how you can push it right if the blood is pushed up this way, it's gotten into this part here and then basically what can happen and some of it can circulate back down right and when it goes and circulates back down what is it gonna do it's gonna push the valves closed to prevent the blood from back flowing into the inferior portion of that vein and that's important rice because that's what keeps them with them basically the blood pooling up and leading to a condition we'll call later varicose veins so that's one important thing for veins to be able to get the blood back up to the a heart so again one thing is valves the second thing that's our extremely important if you remember your veins again are not very high-pressure systems right so if you know usually what your veins are near is they're usually near some muscle so let's say we take.

For example the vein the veins inside of 

your legs are right so let's say here's some skeletal muscles like you're maybe the gastrocnemius soleus muscles right and let's say that they're on both sides actually so let's say here we have another one alright and here's another one and let's say that these muscles contract and when they contract they start squeezing on the blood vessel they start squeezing on to the actual blood vessel and whenever they squeeze onto the blood vessel whenever they shorten they push the blood upwards alright so whenever they push the blood upwards it's called like a muscular milking because it's not very fast it's a slow process but it just keeps contracting and pushing the blood upwards so this right here is called and the second thing here which we described is called a muscular milking all right and it's basically again the muscles are the actual somatic muscles right the skeletal muscles are going to be contracting and pushing the blood upwards that's one another one is called a respiratory pump and a respiratory pump is basically whenever you ant you're breathing you're increasing the thoracic cavity volume right and what it does do.

It does is it actually as you increase 

that thoracic cavity volume it actually can push on some of those actual lower vessels like the inferior vena cava and it can help to push that blood upwards also it can help with the blood coming back from the pulmonary circuit too so it helps to be able to increase the blood flow back to the actual heart and helps to get the blood flow up from the actual lower systemic circuit sorry the systemic veins so that's one so again respiratory pump helps to get more blood from the lungs back to the heart and it helps to get some of the systemic blood back up to the heart right that's called the respiratory pump one more thing that's also important there is tunica media in the blood vessel it's just not that thick right so let's say here I get rid of this part here and I say I draw here a tunica media just a couple smooth muscle cells okay this is important because the tunica media remember to let's say I draw here central nervous system right.

You know that you have your sympathetic 

nerves right and let's say that these sympathetic nerves they come over here and they innervate right the interview there's tunica media and what can that do that can cause Vino constriction so it can also cause a Vino constriction of that smooth muscle and that can also help to be able to push some of the blood is also up there right so the fourth thing that we could also say down here is going to be sympathetic tone now you're probably wondering why I'm mentioning all this like what's so important about it alright so what these valves are 

extremely important the reason why it is 

that some people may be the pseudo BC maybe it's due to standing for long periods of time you know depending upon what it might be these valves can become incompetent and leaky and so what happens is let's say it due to whatever reason is these these these blood vessels start expanding right because of people standing for a long time and the blood is pooling up in that area what starts expanding and then what happens is it pulls so imagine here as I try to pull this blood vessel away from one another I'm pulling these two edges away so then what starts happening to the space between the vet the valves, it starts increasing and then blood starts moving back down as the blood starts moving back down it starts pooling up in one area so imagine all this blood is pooling up in this area.

Here and as the 

blood starts spooling up in this area it starts becoming torturous are twisting right so it starts pulling up and dilating and then it starts becoming torturous is twisted that is called varicose veins they're very common within the calf right so that's one of the common areas another one that they're common in is in the testes there it's actually called varicose eel and what happens is sometimes it's actually more common in the left tested because the gonadal vein the left gonadal vein.

let's say you have your inferior 

vena cava here and then what happens is you have your left gonadal vein it comes up over here with the renal artery right so what happens is it comes up here and it makes this crazy turn to put the blood into the inferior vena cava whereas the right gonadal goes straight to the inferior vena cava so what happens is the blood can actually kind of lead to this backflow into the testes and whenever it backflows into the testes again it can lead to this tour traceur dilating or accumulation of these blood vessels within the testes and that can lead so it's called a varicose seal and that can lead to infertility.

It can lead to dilation it 

can lead to a pretty big scrotum so again if this is the left testes and it starts actually causing this dilation and this torturous formation of these vessels it's called a vertical seal and again this could be a problem because it could lead to inflammation could lead to expansion swelling of the left testicle and on top of that, it could actually lead to infertility okay all right so we talked about varicose seal okay and again what was this problem here call whenever the blood starts pulling up within this area and starts becoming twisting and it becomes torturous and the blood vessel start dilating and it forms these ugly little veins on the back of the leg right that's going again it's called varicose veins okay all right and then another area that's gonna occur it doesn't just have to happen in it within the blood vessels and it doesn't just have to happen here within the testes it can also occur in another part which is the anus right so one of the common areas are the veins inside the anus they're actually called the hemorrhoidal veins sometimes due to high pressure straining forcing to go to the bathroom doing the valves office maneuver and so on and so forth the pressure can accumulate and again that can happen to it so another form of varicose veins is hemorrhoids all right and so that's another example varicose veins.