00:00
Let's spend a little bit at a time with these
heart sounds. I'm going to make a noise for you,
the gallops and there were two sounds
that you head "lerup" with that first noise
and with the second sound, you also heard two
specific sounds and I am enunciating "lerup"
and "darup" on purpose. Now let us walk through
depolarization of the heart, shall we? We begin at the
base. We begin at the right atrium. It then
travels through the atria, then you arrive where?
AV node. From the AV node, what do you
do? You go to the bundle of His and then
you go through the bundle branches. How many
do you have? Through the entire ventricular
septum, you have two bundle branches, left
and right. Physiologically, which bundle branch
do you travel through first? Left bundle
branch, isn't it? If it is a left bundle branch
that you travel through first with depolarization,
what is that going to control? It controls
the mechanical activity of your valves on
your left side in order how would they then
close mitral S1, then aortic S2. Is that clear?
So you pay attention with the closure of the
valves on the left side due to depolarization
passing through your left bundle branch. Hope
that is clear. Now with that said, then you
move on to the right side. Then you have the
right bundle branch. So therefore subsequently,
remember that your nodes with atrial activity fall
through what type of action potential? Close
your eyes. What kind of action potential,
please? It would be 403. Remember those, 403. 4, funny, that's
your sodium channel. And 0, what is that? Calcium.
01:47
And then you have phase III, which is potassium,
403. But then, if you are dealing with mechanical
activity, what kind of action potential is
that? That is the one with the plateau, isn't it? 0, 1, 2, 3, 4.
02:00
Now with both of those in mind, all we are going
to do is keep repeating and if your physio
is not strong then you are having a hard time
following me. But this could also be a point
in which "Maybe I didn't understand my actual
potential as well and I need to go back and
review." And you want to make sure that you have that down
because later on in pharmocology those are
things that come into the play over and over
again. We will do a little bit of that. Now
we have actual closure and we have S1. We have
mitral and then tricuspid now as far as the
type of heart sound that you want to pay attention
to and know everything about would be S2.
02:39
But just to make sure they were clear. S1
will be mitral closure first, then followed
by tricuspid, is that clear? S1, S2. S1 and
then S2 would be A2, P2. We will come then
in a second. Now with S1, I need you to understand when these
atrial-ventricular valves are closing. Atrial-ventricular valve,
that's the other name for these mitral and tricuspid, aren't they?
Of course it is. When would they close? That is your next big
question. Do they close during systole or
diastole? Take your time. Systole, right? Think
what happens during systole. The left ventricle
is about to create all these pressures so that
it is then going to eject blood into the aorta
if the right ventricle is trying to eject
the blood into the pulmonary artery, isn't
it? And so, therefore, you have to open
up the aortic and pulmonic valves. Once again
the question to you, is are you going to create any
heart sounds with opening? Never. And during
systole what then happens to the mitral and
tricuspid? It closes. So from henceforth I
want you to think of S1 as being a systolic
heart sound with the closure of the mitral
and tricuspid. Is that clear? Good. Then we take a look at S2.
With S2, once again what side of the heart
are we dealing with first? Left side. And with
S2, it is the closure of the aortic followed
by the pulmonic. So now we have A2, P2. Clear?
Now your next question is that if there is closure of
these aortic and pulmonic valves,
A2, P2, then when does this occur? During
diastole. Is that clear? During diastole, what happens? My
blood has just been ejected from my left ventricle
and right ventricle and to the aorta and pulmonary
artery respectively. There goes the blood
what has to happen next so that you prevent
any blood regurgitating back into the respective
ventricles. You have to close them. Welcome
to A2, P2. Now as I said, we will walk through
the pathophys of S2 because that is where
the focus should be. Once you have understood
everything that we are going to refer to
in the next couple of slides, then you come
back and take a look at S1. You do that in
order, you are being in great shape.