Structure of the Heart Valves (Nursing)

00:01 If we were to look at the valves all together in a single view with the atria removed, we can see just how similar right and left valves look to each other.

00:10 The pulmonary valve that's sitting just anterior to the aortic valve looks so similar.

00:16 And that's actually because they came from the same artery long time ago during development, and just divided into two almost mirror images of each other.

00:25 We call these semilunar valves because they're basically little halfmoon shapes.

00:30 And they don't have any chordae tendineae or papillary muscles.

00:33 They kind of closed by passive closure.

00:36 But the mitral valve and the tricuspid valve, were quite a bit larger.

00:40 Again, very similar except for the number of leaflets that they had.

00:44 And these are called atrioventricular valves, because they're between the atria and the ventricles.

00:51 So those atrioventricular valves have a bit more going on.

00:55 And it makes sense because they're valves that are going to prevent backflow coming from the ventricle and the ventricles are pumping really hard.

01:03 And so in order to prevent blood from getting shot back into the atria, you're going to need a lot stronger structure than you will from passive flow from a pulmonary artery or aorta.

01:16 So here we see the cusps of those atrial ventricular valves.

01:19 Again, attached to papillary muscles via chordae tendineae.

01:24 And you can see as the heart's beating, how they go into action? So the pulmonary and aortic valve structures have really nothing attached to them.

01:34 They don't really need to, they're shaped as everything you need.

01:37 They're convex, or sort of curved on the ventricle side, so blood can just push them through.

01:43 And then they're cupped on the other side are concave, so that when blood tries to come back, they fill these cusp, and it closes them off, and you don't get any backflow leaking backwards back into the ventricles.

01:56 So let's look at the valves during ventricular contraction, also known as systole.

02:02 So when the myocardium, or heart muscle is contracted, we see that blood is being pushed through the aortic valve.

02:09 It's open, we say.

02:11 But we don't want blood going backwards into the atrium, so the mitral valve is closed.

02:16 You can see where these chordae tendineae and papillary muscles are holding tight to make sure it doesn't get forced backwards into the atrium.

02:27 During ventricular relaxation, also known as diastole, we have the opposite, the myocardium is relaxed.

02:34 and it's going to fill now with blood coming from the atrium.

02:39 But we only want blood coming from the atrium, meaning blood trying to come backwards from the aorta gets closed off by the aortic valve, passively.

02:49 And then the mitral valve is opened, so that that atrial blood can go through and fill the ventricle and start the cycle over again.

02:59 And this all assumes that the valves are working as they're supposed to.

03:03 Meaning the valves are thin, they're compliant, they move out of the way when they're supposed to, and they close when they're supposed to.

03:10 Unfortunately, because valves are opening, closing under pressure, all the time, they accumulate a lot of wear and tear.

03:18 And eventually they can become calcified, and very rigid.

03:22 And when that happens, it can't open very well.

03:26 And when anything along the circulatory system can't open very well, we say it's stenotic.

03:31 So this is a very common condition called aortic stenosis, that's going to make it really hard to open during systole or ventricular contraction, the aortic valve.

03:44 So under normal conditions, the left ventricle is going to contract just enough to make sure that the systemic circulation is going to receive enough pressure to perfuse all the arteries that our body needs.

03:57 But if the aortic valve becomes stenotic, that's going to put a lot more stress and strain on the left ventricle, because it's trying to force its blood through a tinier opening.

04:08 And over time, just like any muscle that's doing more work than it's supposed to, it's going to become hypertrophied.

04:15 And unfortunately, if that goes for too long, it can't compensate anymore, and it can actually start to fail.

04:23 If we look in a bit greater detail around the area of the aortic valve, we notice some interesting features.

04:29 So here's the very beginning of our ascending aorta.

04:33 But before we even get to that we see are these little holes just above the leaflets of the valve.

04:39 We see one on the right called the right coronary ostium.

04:43 Ostium is just another word for hole.

04:45 And that's going to be the opening for our right coronary artery.

04:49 That is the artery that supplies the right side of the heart.

04:52 Similarly, we have a hole on the left called the left coronary ostium.

04:57 That's going to be opening for our left coronary artery.

05:01 The cusp in the middle is actually our posterior cusp, but it's also known as the non-coronary cusp for this reason, it doesn't supply any coronary arteries.