0:02 what guys let's take a look at the
0:05 structure of the heart so we'll think
0:08 about during this brief video we'll
0:09 think about the four chambers of the
0:11 heart will name them and just talk very
0:13 briefly about sort of their roles and
0:16 functions we'll talk then about the four
0:18 valves of the heart and then we'll
0:20 finish up talking about the vessels that
0:23 lead to and from the heart and just try
0:24 and work out what they're called and
0:28 what they do so let's get in so the
0:30 first thing we need to realize is that
0:32 when we're talking about the heart we
0:34 need to decide or define which side of
0:36 the heart we're talking about so imagine
0:37 the heart on the screen is the heart
0:39 that belongs to someone who is facing
0:42 you okay so you're looking at someone
0:46 else's heart facing you so your left is
0:49 their right and your right is their left
0:51 and we do the same with the heart which
0:53 so we define as we look at the heart
0:54 that's currently on the screen the left
0:57 our left is actually the right side of
1:00 the heart and our right is actually the
1:01 left side of the heart because we were
1:03 imagining it's somebody else's heart
1:07 who's facing us so on the right hand
1:08 side of the heart the blood that's
1:10 flowing through the right hand side of
1:12 the heart or the right side of the heart
1:15 is blood that is returning from the body
1:19 so this is blood that's been sent around
1:21 the body and as done what it's needed to
1:23 do is deliver this oxygen and so on and
1:25 picks up carbon dioxide and other things
1:28 and he's now returning from the body to
1:32 the heart and he arrives at the heart
1:35 through veins and we were the way that I
1:36 remember it at least is that the word
1:40 vein contains the word in so a vein is
1:44 any any vessel that is going in or back
1:48 towards in towards the heart so the
1:50 blood that is returning in through the
1:52 veins to the heart on the right side of
1:54 the heart is deoxygenated blood that
1:56 means it's had its oxygen content
2:00 removed not entirely but to a certain
2:02 percentage some of that oxygen has been
2:05 removed and used around in the tissues
2:09 for respiration and from the right side
2:11 of the heart and this will become
2:12 relevant in a moment when we talk about the
2:13 the
2:15 different vessels and the size of the
2:18 vessels and so on from the right side of
2:20 the heart that blood goes to the lungs
2:23 on the left side of the heart which
2:26 again is on our right as we look at
2:28 somebody else's heart the left side the
2:31 heart is receiving blood back from the
2:33 lungs so the right side sends the blood
2:36 to the lungs and then the lungs the
2:37 blood returns from the lungs and when it
2:39 returns from the lungs it arrives in the
2:43 left side of the heart and again because
2:46 it's been to the lungs it's picked up
2:48 oxygen so it's got a greater oxygen
2:50 content now than he did when it arrived
2:52 back from the body so we talked we
2:54 talked about this blood being oxygenated
2:57 blood and then from there it's pumped to
2:59 the body to the various tissues that
3:02 need oxygen to respire via arteries
3:04 arteries and I remember this artery
3:07 begins with an A and so does the word
3:10 away that may or may not help you but
3:15 arteries go away and veins go in and
3:16 what's important to know here just
3:19 briefly before we move on is that on the
3:22 left side the chamber walls of the left
3:24 side of the heart and particularly in
3:27 this lower chamber which we'll explain
3:30 more about in a moment the the chamber
3:33 walls are a lot of thicker a lot thicker
3:35 on the left side the heart and then the
3:37 whole heart is essentially divided into
3:39 two roughly along that black line that
3:41 you can see on the screen and they're
3:45 all there abouts by by part of the heart
3:47 which is known as the septum and that
3:50 the septum simply separates so septum
3:54 separates separates the right side from
3:57 the left side of the heart so let's look
3:59 at the Chamber's so there are four
4:03 chambers you'll recall in the heart and
4:05 the first two we're going to talk about
4:07 are the top two chambers the two
4:10 chambers at the top of the heart which
4:12 you can see labeled here the right
4:15 atrium and the left atrium now that's
4:18 the word atrium is singular you'll
4:20 notice the title of this slide is atria
4:23 that's just the plural okay so one
4:26 atrium two atria
4:28 so we have a left atrium and we have a
4:31 right atrium and you might have heard
4:34 the word atrium used in the context of
4:37 buildings you come into a hallway a
4:40 large entry chamber if you like and that
4:42 is often called the atrium of a building
4:45 so the atrium is the entry chamber and
4:47 that's the same with the heart so these
4:50 are what we might call receiving
4:52 chambers where when the Blood returns to
4:54 the heart the first place it goes
4:55 whether it's coming to the right or the
4:57 left side of the heart the first place
4:59 it goes is it enters into these
5:01 receiving chambers called atria they
5:05 fill with blood and once they're pretty
5:08 much full of blood there's a contraction
5:10 in the atria and the blood is then
5:12 pushed through the valves which we'll
5:13 talk about in a moment
5:16 push through the vowels downwards into
5:19 the larger chambers beneath and those
5:21 larger chambers beneath are called
5:24 ventricles and when the blood is pushed
5:27 through the atria contract initially
5:30 whilst the ventricles are relaxed and
5:32 the blood flows into the ventricles so
5:34 we've got two ventricles as well so you
5:36 can see where the atria are the
5:38 ventricles are underneath them and these
5:40 are the larger chambers underneath so
5:41 there we are on the diagram left
5:43 ventricle down there and the right
5:46 ventricle underneath the right atrium so
5:48 these are larger chambers and we
5:50 sometimes refer to these as discharging
5:52 chambers because they're the Chamber's
5:54 from which when they contract blood is
5:57 ejected the blood goes out from the heart
5:57 heart
5:59 via the ventricles it's kind of the last
6:02 port of call if you like as it as the
6:03 blood is leaving the heart whether it's
6:05 going to the lungs or to the body and
6:07 the ventricles contract and send blood
6:11 out of the heart so the left ventricle
6:16 sends blood to the body and the right
6:19 ventricle sends blood to the lungs and
6:21 you'll notice that there are different
6:24 in size and in particular different in
6:27 thickness so that the muscle wall so the
6:29 heart muscle the cardiac most of the
6:31 wall is much thicker on the left-hand
6:34 side of the heart and the reason for
6:36 that is the left side as it says on the
6:38 screen now the left side the left
6:39 ventricle is pumping blood
6:41 to the body which means it's got a far
6:44 greater distance to go than the right
6:46 side which only needs to pump to the
6:48 lungs and as you know from your a and P
6:51 the lungs are right there next to the
6:53 heart so there doesn't require as much
6:56 pressure doesn't require therefore the
6:58 muscle to be quite quite as thick or as
7:00 powerful on the right side because the
7:02 Bloods only got to get to the lungs and
7:04 back whereas on the left side of the
7:07 heart it's much more muscular because
7:09 there needs to be a much greater amount
7:11 of pressure in order to eject that blood
7:14 and get it to continue its circuit
7:16 around the entire body and return again
7:18 to the heart and back again to the right
7:24 atrium so there are four valves as well
7:28 four valves that separate these chambers
7:30 from one another and keep blood from
7:33 just flowing forwards backwards or
7:37 wherever at any given time so the four
7:39 vows of these the first valve is the
7:42 bicuspid valve and often it's called the
7:45 mitral valve and either of those names
7:50 is fine and that is there between the
7:53 left atrium and the left ventricle and
7:56 it simply stops blood from flowing from
7:58 the atrium into the ventricle before
8:01 it's ready to do so on the other side of
8:05 the heart between the the right atrium
8:07 and the right ventricle we've got the
8:10 tricuspid valve and there it is on the
8:13 diagram then between the ventricles and
8:16 the the vessels that lead out of the
8:19 heart we've got another pair or another
8:21 set of valves that stop the blood from
8:25 being ejected from the ventricles until
8:26 the pressure is great enough to actually
8:28 send the blood where it needs to go so
8:31 we've got two semilunar valves one is
8:34 the semilunar or aortic valve which is
8:37 circled they're not the greatest diagram
8:39 unfortunately to represent where the
8:42 aortic valve is but blood leaving the
8:44 the left ventricle goes through the
8:46 aortic valve and into that very large
8:49 red vessel that you can see at the top
8:50 there which is the aorta and we'll come
8:52 to that again in a second
8:54 then we've also got another semilunar
8:58 valve which is circled there and that is
9:01 the pulmonary or pulmonary valve and
9:03 Palmer is simply is a word that we use
9:06 that means to relate to the heart so
9:07 whenever you hear our pulmonary or
9:09 pulmonary we're talking about sorry not
9:12 the heart the lungs relates to the lungs
9:15 so when we talk about cardio pulmonary
9:19 respiration or cardiopulmonary
9:23 resuscitation CPR the pbut the pulmonary
9:26 bit means to do with the lungs the
9:29 semilunar or polo nary pulmonary valve
9:31 is the one that allows blood to flow
9:33 through it before it heads to the lungs
9:35 so the purpose of all these valves is
9:38 essentially the same the first thing
9:39 they do is they prevent blood from
9:42 flowing in the wrong direction so what
9:43 we don't want is when the atria are
9:46 contracted when the atria contract we
9:48 don't want the blood flowing back out of
9:50 the heart we wanted to flow through into
9:52 the right direction into the ventricles
9:54 but then in once the blood is in the
9:56 ventricles we also don't want it to flow
9:59 back into the atria so that the mitral
10:00 valve and the the bicuspid and the
10:04 tricuspid valves closed when the
10:06 ventricles contract and then blood flows
10:08 out the way we want it to flow so it
10:09 prevents blood flowing in the wrong
10:14 direction and these these valves
10:15 particularly the tricuspid and the
10:18 bicuspid valves are held in place by
10:21 what we call heart strings or cord cord
10:25 I tend in AI chordae tendineae through
10:27 heartstrings that they're basically sort
10:29 of tendons
10:33 that keep the vowels from inverting from
10:35 from turning inside out and going the
10:35 wrong way
10:37 they sort of hold them in place to make
10:38 sure that blood can only flow one way
10:41 and any pressure that's pressed back on
10:43 them they don't invert they stay in
10:45 place so the blood can't flow the wrong
10:48 way and the phrases you'll notice
10:51 semilunar semilunar tricuspid bicuspid
10:54 the cuspid and the lunar parts of those
10:56 words just describe the shape of them so
11:00 the cuspid means that they form a sort
11:02 of a peak so you may have heard people
11:04 talking about being on the cusp of a wave
11:05 wave
11:08 example so when a wave forms and he
11:10 rises up and just before the moment the
11:13 wave breaks it rises into a peak that
11:15 peak is known as the cusp that peak is
11:19 known as the cusp and Luna means moon
11:23 shaped moon shaped so the tricuspid and
11:26 bicuspid valves peak and they're held in
11:29 that shape by the chordae tendineae eye
11:32 and the semilunar valves are sort of
11:35 half semi lunar half moon shaped and
11:37 that's what keeps them in place and it
11:38 allows blood to flow in one direction
11:42 but not in the other direction so what
11:44 about finally the major arteries and
11:48 veins that that allow blood to flow to
11:52 and from the heart so initially we've
11:54 got the aorta which I've already
11:56 mentioned that so that very large vessel
11:59 at the top of the heart there that's
12:01 labeled on the screen that is the aorta
12:04 and the aorta is the largest artery in
12:06 the body in terms of diameter it's the
12:10 largest artery in the body and because
12:13 the blood is being squeezed from the
12:15 left ventricle at great pressure really
12:16 high pressure and again that's because
12:18 it's got to go a long way it's gonna get
12:19 around the entire body
12:22 they oughta experience these really high
12:24 blood pressure fact the highest blood
12:26 pressure anywhere in the entire
12:29 cardiovascular system is found in the
12:31 aorta and so therefore the aorta needs
12:34 to be really elastic has to be quite
12:36 stretchy in order to account for the
12:38 changes in blood pressure especially
12:40 during exercise where blood pressure
12:45 really shoots up very high CoA otto's
12:47 you can sort of see from the diagram it
12:51 loops up and it heads off towards the
12:54 top part of the body but also it loops
12:57 down back behind the heart and splits
13:00 again below the diagram that we've got
13:02 on the screen splits down around the
13:04 level of the diaphragm and then splits
13:08 off and heads off down to the legs the
13:12 vena cava or vena cava is this blue
13:15 colored vessel on the on the right side
13:16 of the heart as the left as we look at it
13:17 it
13:20 and there we have the two parts of it
13:24 it's one vessel really but we we call
13:28 the superior part of the vessel or the
13:30 vena cava at the top is the superior
13:31 vena cava superior meaning at the top
13:34 and inferior vena cava the vena cava at
13:37 the bottom so both join together just
13:41 before just as they returned into or
13:44 returned blood into the right atrium so
13:46 the superior vena cava brings blood from
13:48 above the heart is pretty obvious and
13:50 the inferior vena cava brings blood from
13:55 below the heart so finally last thing to
13:59 note is some more some more arteries and
14:02 veins so here we've got the pulmonary
14:04 vein so I've already said that pulmonary
14:07 relates to the lungs and so the vein is
14:11 the vessel going in vein contains the
14:13 word in the vessel going into the heart
14:16 from the lungs and it's that purple one
14:18 there there's one on either side you can
14:20 see the other one poking out the side of
14:23 the superior vena cava there and the
14:25 role of the pulmonary vein is to simply
14:27 bring the blood back from the lungs so
14:29 not very far back from the lungs back to
14:29 the heart
14:32 so obviously that that blood that's
14:33 returning from the lungs has been
14:35 oxygenated and this is interesting
14:38 because the pulmonary vein is the only
14:42 vein that carries oxygenated blood it's
14:44 a vein because it's going into the heart
14:46 that's what a vein is that's how we
14:49 classify it but the pulmonary vein has
14:51 already picked up oxygen from the lungs
14:53 and is bringing it to the heart ready to
14:55 be sent around the body so therefore
14:56 it's the only vein that carries
15:00 oxygenated blood the pulmonary artery on
15:02 the other hand is this one so the
15:05 pulmonary artery a four away artery this
15:08 is where blood from the right side of
15:10 the heart or that's come back from the
15:12 body it's already deoxygenated it's
15:15 heading towards the lungs to pick up a
15:17 load more oxygen and to drop off the
15:19 carbon dioxide so it's because it's
15:21 going away from the heart it's an artery
15:22 it's a pulmonary artery which is going
15:26 away to the lungs as we've said here it
15:27 goes from the heart to the lungs and
15:31 again interestingly this is the only art
15:37 that carries deoxygenated blood I hope
15:38 that's been helpful and to get us
15:40 started on understanding the structure
