[Script Info]
Title: 
[Events]
Format: Layer, Start, End, Style, Name, MarginL, MarginR, MarginV, Effect, Text
Dialogue: 0,0:00:02.42,0:00:04.81,Default,,0000,0000,0000,,I want to talk a little bit\Nabout the idea of pressure
Dialogue: 0,0:00:04.81,0:00:05.63,Default,,0000,0000,0000,,and volume.
Dialogue: 0,0:00:05.63,0:00:07.56,Default,,0000,0000,0000,,And we're actually\Na clear up some
Dialogue: 0,0:00:07.56,0:00:10.66,Default,,0000,0000,0000,,misconceptions I think\NI may have caused.
Dialogue: 0,0:00:10.66,0:00:12.06,Default,,0000,0000,0000,,I apologize for them.
Dialogue: 0,0:00:12.06,0:00:13.73,Default,,0000,0000,0000,,But I think this is\Na good chance for us
Dialogue: 0,0:00:13.73,0:00:15.87,Default,,0000,0000,0000,,to reflect on the things\Nthat we've learned
Dialogue: 0,0:00:15.87,0:00:18.29,Default,,0000,0000,0000,,and also build up a\Ncouple of new ideas.
Dialogue: 0,0:00:18.29,0:00:22.98,Default,,0000,0000,0000,,So let's draw volume going\Nthat way and pressure going up.
Dialogue: 0,0:00:22.98,0:00:25.51,Default,,0000,0000,0000,,And one of things I\Nwant to start with
Dialogue: 0,0:00:25.51,0:00:30.19,Default,,0000,0000,0000,,was the end systolic\Npressure volume relationship.
Dialogue: 0,0:00:30.19,0:00:31.78,Default,,0000,0000,0000,,We drew it something like this.
Dialogue: 0,0:00:31.78,0:00:34.14,Default,,0000,0000,0000,,So we said this is\Nthe relationship
Dialogue: 0,0:00:34.14,0:00:36.74,Default,,0000,0000,0000,,at the end of systole\Nbetween the two,
Dialogue: 0,0:00:36.74,0:00:39.07,Default,,0000,0000,0000,,between pressure and volume.
Dialogue: 0,0:00:39.07,0:00:41.99,Default,,0000,0000,0000,,And one thing that I wanted\Nto bring up immediately
Dialogue: 0,0:00:41.99,0:00:44.78,Default,,0000,0000,0000,,was the idea of\Nincreasing volume.
Dialogue: 0,0:00:44.78,0:00:48.67,Default,,0000,0000,0000,,So as I go up to this yellow\Nline, I'm increasing volume.
Dialogue: 0,0:00:48.67,0:00:51.13,Default,,0000,0000,0000,,And sometimes the way I've\Ndrawn that-- actually maybe I'll
Dialogue: 0,0:00:51.13,0:00:54.06,Default,,0000,0000,0000,,make a little bit of\Nspace on this canvas.
Dialogue: 0,0:00:54.06,0:00:56.58,Default,,0000,0000,0000,,And sometimes the way I\Ndraw an increase in volume
Dialogue: 0,0:00:56.58,0:00:58.84,Default,,0000,0000,0000,,can be a little bit misleading.
Dialogue: 0,0:00:58.84,0:01:00.51,Default,,0000,0000,0000,,So I've drawn, for\Nexample, in the past,
Dialogue: 0,0:01:00.51,0:01:03.45,Default,,0000,0000,0000,,I've drawn a left\Nventricle like this.
Dialogue: 0,0:01:03.45,0:01:06.55,Default,,0000,0000,0000,,And I said well as blood\Ngoes into my left ventricle,
Dialogue: 0,0:01:06.55,0:01:08.09,Default,,0000,0000,0000,,it basically does this.
Dialogue: 0,0:01:08.09,0:01:10.80,Default,,0000,0000,0000,,You have more and more\Nblood filling up the heart.
Dialogue: 0,0:01:10.80,0:01:13.59,Default,,0000,0000,0000,,And I've drawn this\Nsort of a picture,
Dialogue: 0,0:01:13.59,0:01:16.21,Default,,0000,0000,0000,,and it really does tell\Nyou about a couple things.
Dialogue: 0,0:01:16.21,0:01:19.58,Default,,0000,0000,0000,,It tells you that you\Nhave filling happening.
Dialogue: 0,0:01:19.58,0:01:21.27,Default,,0000,0000,0000,,And that part, I'm OK with.
Dialogue: 0,0:01:21.27,0:01:22.72,Default,,0000,0000,0000,,But the part that\NI'm not OK with
Dialogue: 0,0:01:22.72,0:01:24.39,Default,,0000,0000,0000,,is the idea that\Nit basically seems
Dialogue: 0,0:01:24.39,0:01:26.71,Default,,0000,0000,0000,,like you have a fixed volume.
Dialogue: 0,0:01:26.71,0:01:30.82,Default,,0000,0000,0000,,It looks like a fixed\Nvolume on the heart,
Dialogue: 0,0:01:30.82,0:01:32.36,Default,,0000,0000,0000,,or the left ventricle anyway.
Dialogue: 0,0:01:32.36,0:01:34.13,Default,,0000,0000,0000,,And it almost makes\Nit look like you're
Dialogue: 0,0:01:34.13,0:01:36.15,Default,,0000,0000,0000,,filling up a glass of water.
Dialogue: 0,0:01:36.15,0:01:39.66,Default,,0000,0000,0000,,Basically, that's kind of\Nwhat it looks like a glass.
Dialogue: 0,0:01:39.66,0:01:43.40,Default,,0000,0000,0000,,And really the correct way to\Nthink about left ventricular
Dialogue: 0,0:01:43.40,0:01:46.20,Default,,0000,0000,0000,,filling is a little\Nbit more like this.
Dialogue: 0,0:01:46.20,0:01:49.46,Default,,0000,0000,0000,,You should be thinking of\Nit more along the lines
Dialogue: 0,0:01:49.46,0:01:52.16,Default,,0000,0000,0000,,of a picture like this\Nwhere you basically
Dialogue: 0,0:01:52.16,0:01:56.94,Default,,0000,0000,0000,,have a smaller volumed the\Nleft ventricle filling up
Dialogue: 0,0:01:56.94,0:01:58.31,Default,,0000,0000,0000,,with blood.
Dialogue: 0,0:01:58.31,0:02:01.59,Default,,0000,0000,0000,,And over time it kind\Nof feels in completely.
Dialogue: 0,0:02:01.59,0:02:03.30,Default,,0000,0000,0000,,So it starts out like that.
Dialogue: 0,0:02:03.30,0:02:05.51,Default,,0000,0000,0000,,And then you add more blood\Nand it becomes like that.
Dialogue: 0,0:02:05.51,0:02:07.66,Default,,0000,0000,0000,,And then you finally\Nfill it up like that.
Dialogue: 0,0:02:07.66,0:02:09.99,Default,,0000,0000,0000,,So that would be the\Nmore accurate way
Dialogue: 0,0:02:09.99,0:02:12.13,Default,,0000,0000,0000,,of showing what's going\Non in the left ventricle.
Dialogue: 0,0:02:12.13,0:02:13.59,Default,,0000,0000,0000,,And, of course,\Nall three of these,
Dialogue: 0,0:02:13.59,0:02:17.00,Default,,0000,0000,0000,,then, are the left ventricle\Nat different points in time.
Dialogue: 0,0:02:17.00,0:02:21.32,Default,,0000,0000,0000,,So this second picture also\Ntells you about filling,
Dialogue: 0,0:02:21.32,0:02:23.93,Default,,0000,0000,0000,,so you get the idea that\Nblood is filling in the heart.
Dialogue: 0,0:02:23.93,0:02:26.24,Default,,0000,0000,0000,,But it does a better\Njob of showing you
Dialogue: 0,0:02:26.24,0:02:29.03,Default,,0000,0000,0000,,that the volume changes.
Dialogue: 0,0:02:29.03,0:02:33.90,Default,,0000,0000,0000,,The volume of the left ventricle\Nchanges, so it's not fixed.
Dialogue: 0,0:02:33.90,0:02:34.74,Default,,0000,0000,0000,,And that's correct.
Dialogue: 0,0:02:34.74,0:02:36.79,Default,,0000,0000,0000,,This is the better\Nway of looking at it.
Dialogue: 0,0:02:36.79,0:02:39.41,Default,,0000,0000,0000,,And kind of an analogy\Nmight be a balloon,
Dialogue: 0,0:02:39.41,0:02:43.42,Default,,0000,0000,0000,,you might think of a balloon\Nfor this filling process.
Dialogue: 0,0:02:43.42,0:02:47.56,Default,,0000,0000,0000,,So I want to be very clear\Nthat the left ventricle is not
Dialogue: 0,0:02:47.56,0:02:48.85,Default,,0000,0000,0000,,like a glass.
Dialogue: 0,0:02:48.85,0:02:50.34,Default,,0000,0000,0000,,It's like a balloon.
Dialogue: 0,0:02:50.34,0:02:52.61,Default,,0000,0000,0000,,And that it's not\Na fixed volume.
Dialogue: 0,0:02:52.61,0:02:54.25,Default,,0000,0000,0000,,It actually changes.
Dialogue: 0,0:02:54.25,0:02:56.75,Default,,0000,0000,0000,,So this is probably the more\Naccurate way of thinking about.
Dialogue: 0,0:02:56.75,0:03:00.28,Default,,0000,0000,0000,,And I apologize for doing\Nthis sort of a drawing.
Dialogue: 0,0:03:00.28,0:03:02.19,Default,,0000,0000,0000,,Truthfully, I didn't\Nmean to confuse anyone,
Dialogue: 0,0:03:02.19,0:03:04.79,Default,,0000,0000,0000,,but I just want to\Ndemonstrate filling.
Dialogue: 0,0:03:04.79,0:03:07.94,Default,,0000,0000,0000,,And I probably just do it\Nin a quick and hurried way.
Dialogue: 0,0:03:07.94,0:03:09.65,Default,,0000,0000,0000,,And so I want to\Nclarify that point now.
Dialogue: 0,0:03:09.65,0:03:11.44,Default,,0000,0000,0000,,So this is what it\Nwould look like.
Dialogue: 0,0:03:11.44,0:03:13.33,Default,,0000,0000,0000,,And actually I could\Ntake this a step further
Dialogue: 0,0:03:13.33,0:03:16.12,Default,,0000,0000,0000,,and say well what\Nif I was to do this?
Dialogue: 0,0:03:16.12,0:03:19.89,Default,,0000,0000,0000,,What if I was to take a\Ncross section like that,
Dialogue: 0,0:03:19.89,0:03:23.67,Default,,0000,0000,0000,,cut it with a blade at\Nthese three points in time?
Dialogue: 0,0:03:23.67,0:03:25.42,Default,,0000,0000,0000,,Wouldn't you agree\Nthat you would actually
Dialogue: 0,0:03:25.42,0:03:29.23,Default,,0000,0000,0000,,get an interesting cross\Nsection view of it,
Dialogue: 0,0:03:29.23,0:03:31.05,Default,,0000,0000,0000,,if I was to take\Nit like that and I
Dialogue: 0,0:03:31.05,0:03:33.53,Default,,0000,0000,0000,,was to erase these top bits out.
Dialogue: 0,0:03:33.53,0:03:35.84,Default,,0000,0000,0000,,And you were to now\Nlook down at the heart,
Dialogue: 0,0:03:35.84,0:03:40.12,Default,,0000,0000,0000,,you'd basically see kind\Nof an interesting view.
Dialogue: 0,0:03:40.12,0:03:42.66,Default,,0000,0000,0000,,And I'll actually try to\Ndraw that view out for you.
Dialogue: 0,0:03:42.66,0:03:45.16,Default,,0000,0000,0000,,And it's helpful actually\Nto do it that way.
Dialogue: 0,0:03:45.16,0:03:47.96,Default,,0000,0000,0000,,And I'll tell you why So\Nthis one would basically
Dialogue: 0,0:03:47.96,0:03:50.30,Default,,0000,0000,0000,,look like this.
Dialogue: 0,0:03:50.30,0:03:54.16,Default,,0000,0000,0000,,And this one would\Nlook like this.
Dialogue: 0,0:03:54.16,0:03:55.90,Default,,0000,0000,0000,,And this one might\Nlook much larger
Dialogue: 0,0:03:55.90,0:03:57.69,Default,,0000,0000,0000,,than the other two\Nsomething like this.
Dialogue: 0,0:03:57.69,0:03:59.99,Default,,0000,0000,0000,,And again this is just\Nlooking at a cross section,
Dialogue: 0,0:03:59.99,0:04:01.36,Default,,0000,0000,0000,,so it's nothing\Ndifferent at all.
Dialogue: 0,0:04:01.36,0:04:04.29,Default,,0000,0000,0000,,It's just looking at\Nthe cut surface of it.
Dialogue: 0,0:04:04.29,0:04:07.42,Default,,0000,0000,0000,,And all three you'd\Nexpect to be full.
Dialogue: 0,0:04:07.42,0:04:10.44,Default,,0000,0000,0000,,So this is how I'm going\Nto use our diagram.
Dialogue: 0,0:04:10.44,0:04:12.40,Default,,0000,0000,0000,,I'm actually going to\Nuse these kinds of images
Dialogue: 0,0:04:12.40,0:04:15.75,Default,,0000,0000,0000,,now to show what filling of\Nthe left ventricle looks like,
Dialogue: 0,0:04:15.75,0:04:19.16,Default,,0000,0000,0000,,so we can actually get\Na real sense for it.
Dialogue: 0,0:04:19.16,0:04:22.42,Default,,0000,0000,0000,,And you'll see an interesting\Nproblem that comes up.
Dialogue: 0,0:04:22.42,0:04:24.24,Default,,0000,0000,0000,,So let's do that.
Dialogue: 0,0:04:24.24,0:04:25.76,Default,,0000,0000,0000,,Let's draw a couple\Nof circles here.
Dialogue: 0,0:04:25.76,0:04:28.14,Default,,0000,0000,0000,,I'm going to draw, let's\Nsay, a big circle here
Dialogue: 0,0:04:28.14,0:04:30.05,Default,,0000,0000,0000,,where it's really large.
Dialogue: 0,0:04:30.05,0:04:32.60,Default,,0000,0000,0000,,And then let's say the volume\Nis little small at this point.
Dialogue: 0,0:04:32.60,0:04:34.19,Default,,0000,0000,0000,,So let's draw\Nsomething like that.
Dialogue: 0,0:04:34.19,0:04:36.44,Default,,0000,0000,0000,,And the volume is\Nreally, really tiny.
Dialogue: 0,0:04:36.44,0:04:38.26,Default,,0000,0000,0000,,Let's draw something\Nlike that over here.
Dialogue: 0,0:04:38.26,0:04:41.41,Default,,0000,0000,0000,,Now if you have these three\Nvolumes, you might say,
Dialogue: 0,0:04:41.41,0:04:44.34,Default,,0000,0000,0000,,well, OK you've colored them in.
Dialogue: 0,0:04:44.34,0:04:47.25,Default,,0000,0000,0000,,Well, one thing\Nyou'd have to admit
Dialogue: 0,0:04:47.25,0:04:50.99,Default,,0000,0000,0000,,and you'd realize pretty\Nsoon is that at the bottom
Dialogue: 0,0:04:50.99,0:04:53.81,Default,,0000,0000,0000,,of this curve, you\Nhave a small volume,
Dialogue: 0,0:04:53.81,0:04:57.23,Default,,0000,0000,0000,,but it does take a little bit\Nof blood to fill that volume in.
Dialogue: 0,0:04:57.23,0:04:58.85,Default,,0000,0000,0000,,When you have zero\Nvolume-- like right
Dialogue: 0,0:04:58.85,0:05:01.06,Default,,0000,0000,0000,,here there's zero\Nblood in there--
Dialogue: 0,0:05:01.06,0:05:03.78,Default,,0000,0000,0000,,it would be an empty\Nleft ventricle.
Dialogue: 0,0:05:03.78,0:05:06.11,Default,,0000,0000,0000,,And then you'd actually add\Na little bit of blood to it.
Dialogue: 0,0:05:06.11,0:05:07.69,Default,,0000,0000,0000,,Let's say you fill it up.
Dialogue: 0,0:05:07.69,0:05:09.42,Default,,0000,0000,0000,,Let's say halfway.
Dialogue: 0,0:05:09.42,0:05:11.92,Default,,0000,0000,0000,,And now you've got a\Nhalf full ventricle.
Dialogue: 0,0:05:11.92,0:05:14.29,Default,,0000,0000,0000,,And then you keep doing it\Nand you have a full ventricle.
Dialogue: 0,0:05:14.29,0:05:18.67,Default,,0000,0000,0000,,So you basically are going\Nthis way along the curve.
Dialogue: 0,0:05:18.67,0:05:20.64,Default,,0000,0000,0000,,But until you have\Na full ventricle,
Dialogue: 0,0:05:20.64,0:05:23.02,Default,,0000,0000,0000,,and this is the point, until\Nyou have a full ventricle
Dialogue: 0,0:05:23.02,0:05:25.93,Default,,0000,0000,0000,,you actually don't have\Nany increase in pressure.
Dialogue: 0,0:05:25.93,0:05:28.99,Default,,0000,0000,0000,,So previously when I drew\Nout the end systolic pressure
Dialogue: 0,0:05:28.99,0:05:32.06,Default,,0000,0000,0000,,volume relationship\Nwith that yellow line,
Dialogue: 0,0:05:32.06,0:05:34.30,Default,,0000,0000,0000,,I drew it the way\Nyou see it now.
Dialogue: 0,0:05:34.30,0:05:37.58,Default,,0000,0000,0000,,But now I'm telling you that\Nthe truth is that it actually
Dialogue: 0,0:05:37.58,0:05:39.25,Default,,0000,0000,0000,,looks a little bit\Ndifferent, especially
Dialogue: 0,0:05:39.25,0:05:40.73,Default,,0000,0000,0000,,at the bottom end of this curve.
Dialogue: 0,0:05:40.73,0:05:43.76,Default,,0000,0000,0000,,So I'm going to erase this\Nand draw it in properly.
Dialogue: 0,0:05:43.76,0:05:46.05,Default,,0000,0000,0000,,And this is the more accurate\Nway of drawing it in.
Dialogue: 0,0:05:46.05,0:05:48.50,Default,,0000,0000,0000,,You basically have\Nalmost no-- or really no
Dialogue: 0,0:05:48.50,0:05:49.37,Default,,0000,0000,0000,,increase in pressure.
Dialogue: 0,0:05:49.37,0:05:51.52,Default,,0000,0000,0000,,I shouldn't say almost no.
Dialogue: 0,0:05:51.52,0:05:55.20,Default,,0000,0000,0000,,And then once you get\Nto a full ventricle,
Dialogue: 0,0:05:55.20,0:05:57.11,Default,,0000,0000,0000,,now you start seeing an\Nincrease in pressure.
Dialogue: 0,0:05:57.11,0:06:00.19,Default,,0000,0000,0000,,And really the way that an\Nincrease in pressure looks
Dialogue: 0,0:06:00.19,0:06:02.80,Default,,0000,0000,0000,,is that you have\Na larger volume.
Dialogue: 0,0:06:02.80,0:06:04.43,Default,,0000,0000,0000,,And that's what you're\Nstarting to see.
Dialogue: 0,0:06:04.43,0:06:06.69,Default,,0000,0000,0000,,You're start to see\Nthat larger volume.
Dialogue: 0,0:06:06.69,0:06:08.44,Default,,0000,0000,0000,,So even a tiny\Nbit of pressure is
Dialogue: 0,0:06:08.44,0:06:10.80,Default,,0000,0000,0000,,going to push out on\Nthe left ventricle.
Dialogue: 0,0:06:10.80,0:06:13.76,Default,,0000,0000,0000,,And you'd actually notice that\Nbecause now it gets larger.
Dialogue: 0,0:06:13.76,0:06:15.97,Default,,0000,0000,0000,,So the left ventricle actually\Ndoesn't change in size
Dialogue: 0,0:06:15.97,0:06:16.86,Default,,0000,0000,0000,,initially.
Dialogue: 0,0:06:16.86,0:06:19.32,Default,,0000,0000,0000,,And, finally, when the pressure\Nstarts actually mounting up
Dialogue: 0,0:06:19.32,0:06:21.22,Default,,0000,0000,0000,,it starts changing in size.
Dialogue: 0,0:06:21.22,0:06:23.05,Default,,0000,0000,0000,,So you can start\Nappreciating why
Dialogue: 0,0:06:23.05,0:06:26.57,Default,,0000,0000,0000,,I am saying that this first\Nyellow line is incorrect.
Dialogue: 0,0:06:26.57,0:06:29.50,Default,,0000,0000,0000,,Let me erase it completely\Nso it doesn't distract you.
Dialogue: 0,0:06:29.50,0:06:32.40,Default,,0000,0000,0000,,So I've drawn out the end\Nsystolic pressure volume
Dialogue: 0,0:06:32.40,0:06:35.38,Default,,0000,0000,0000,,relationship, but what I\Nwant to do is now add to it
Dialogue: 0,0:06:35.38,0:06:38.46,Default,,0000,0000,0000,,our end diastolic pressure\Nvolume relationship.
Dialogue: 0,0:06:38.46,0:06:40.43,Default,,0000,0000,0000,,We know it goes\Nsomething like that.
Dialogue: 0,0:06:40.43,0:06:42.79,Default,,0000,0000,0000,,And let me just label\Nit in a yellow color
Dialogue: 0,0:06:42.79,0:06:45.00,Default,,0000,0000,0000,,just to be parallel.
Dialogue: 0,0:06:45.00,0:06:49.57,Default,,0000,0000,0000,,So this is our end diastolic\Npressure volume relationship.
Dialogue: 0,0:06:49.57,0:06:53.68,Default,,0000,0000,0000,,Now if I was to say, well, what\Nwould the cross section look
Dialogue: 0,0:06:53.68,0:06:54.18,Default,,0000,0000,0000,,like?
Dialogue: 0,0:06:54.18,0:06:56.45,Default,,0000,0000,0000,,Now let's just kind of\Nchoose a couple points
Dialogue: 0,0:06:56.45,0:06:57.57,Default,,0000,0000,0000,,to say this is this point.
Dialogue: 0,0:06:57.57,0:07:00.96,Default,,0000,0000,0000,,This is this point like that.
Dialogue: 0,0:07:00.96,0:07:05.03,Default,,0000,0000,0000,,And if I said what would\Nthe same volume look like
Dialogue: 0,0:07:05.03,0:07:07.01,Default,,0000,0000,0000,,on the other curve, I\Nwould have to actually
Dialogue: 0,0:07:07.01,0:07:09.50,Default,,0000,0000,0000,,just draw a line\Ndown and say, OK.
Dialogue: 0,0:07:09.50,0:07:12.17,Default,,0000,0000,0000,,This is this volume right here.
Dialogue: 0,0:07:12.17,0:07:17.09,Default,,0000,0000,0000,,And this is this\Nvolume down here.
Dialogue: 0,0:07:17.09,0:07:19.95,Default,,0000,0000,0000,,And along those\Npoints-- let me ask
Dialogue: 0,0:07:19.95,0:07:23.32,Default,,0000,0000,0000,,you just mark it\Non my other curve.
Dialogue: 0,0:07:23.32,0:07:25.39,Default,,0000,0000,0000,,Those points would\Nbe right there.
Dialogue: 0,0:07:25.39,0:07:27.87,Default,,0000,0000,0000,,And I actually could just\Nsimilarly draw them out.
Dialogue: 0,0:07:27.87,0:07:32.05,Default,,0000,0000,0000,,I could say well\Nthis is about that.
Dialogue: 0,0:07:32.05,0:07:35.12,Default,,0000,0000,0000,,And then the other one looks\Nmaybe a little bit larger.
Dialogue: 0,0:07:35.12,0:07:37.33,Default,,0000,0000,0000,,It would be something like that.
Dialogue: 0,0:07:37.33,0:07:38.80,Default,,0000,0000,0000,,So these are my two curves.
Dialogue: 0,0:07:38.80,0:07:39.30,Default,,0000,0000,0000,,Right?
Dialogue: 0,0:07:39.30,0:07:41.59,Default,,0000,0000,0000,,Now I'm trying to make them\Nlook as similar as possible
Dialogue: 0,0:07:41.59,0:07:42.46,Default,,0000,0000,0000,,to the other ones.
Dialogue: 0,0:07:42.46,0:07:43.97,Default,,0000,0000,0000,,And I'll fill them in.
Dialogue: 0,0:07:43.97,0:07:47.26,Default,,0000,0000,0000,,So that's what the volumes\Nwould look like at these points.
Dialogue: 0,0:07:47.26,0:07:52.21,Default,,0000,0000,0000,,So really when you\Nlook at the volumes,
Dialogue: 0,0:07:52.21,0:07:53.41,Default,,0000,0000,0000,,they look about the same.
Dialogue: 0,0:07:53.41,0:07:55.05,Default,,0000,0000,0000,,They don't look any\Ndifferent at all.
Dialogue: 0,0:07:55.05,0:07:57.59,Default,,0000,0000,0000,,And so you're left wondering\Nwell how in the world is it--
Dialogue: 0,0:07:57.59,0:07:59.68,Default,,0000,0000,0000,,and this is actually very,\Nvery confusing to think
Dialogue: 0,0:07:59.68,0:08:01.83,Default,,0000,0000,0000,,about for folks-- how\Nin the world is it
Dialogue: 0,0:08:01.83,0:08:06.39,Default,,0000,0000,0000,,that the pressure is so darn\Nhigh on the end systolic curve
Dialogue: 0,0:08:06.39,0:08:09.65,Default,,0000,0000,0000,,whereas it's low on the end\Ndiastolic curve, when they look
Dialogue: 0,0:08:09.65,0:08:10.31,Default,,0000,0000,0000,,the same?
Dialogue: 0,0:08:10.31,0:08:12.33,Default,,0000,0000,0000,,They don't look any different.
Dialogue: 0,0:08:12.33,0:08:16.73,Default,,0000,0000,0000,,And to figure this out-- I think\None easy trick I've been using
Dialogue: 0,0:08:16.73,0:08:21.46,Default,,0000,0000,0000,,is to just imagine what's\Nhappening at the muscle level.
Dialogue: 0,0:08:21.46,0:08:24.96,Default,,0000,0000,0000,,So the muscle cells are kind\Nof contracting and pulling
Dialogue: 0,0:08:24.96,0:08:26.96,Default,,0000,0000,0000,,in those z-disks.
Dialogue: 0,0:08:26.96,0:08:30.76,Default,,0000,0000,0000,,At the end of systole, we've got\Ntons of contraction happening.
Dialogue: 0,0:08:30.76,0:08:33.08,Default,,0000,0000,0000,,And it's happening here too.
Dialogue: 0,0:08:33.08,0:08:38.42,Default,,0000,0000,0000,,In fact, it's happening at\Nevery part of this curve.
Dialogue: 0,0:08:38.42,0:08:40.90,Default,,0000,0000,0000,,And if I was to try to simplify\Nthis, instead of drawing
Dialogue: 0,0:08:40.90,0:08:42.80,Default,,0000,0000,0000,,hundreds of arrows\Nlike this, I could
Dialogue: 0,0:08:42.80,0:08:44.17,Default,,0000,0000,0000,,do this for every single point.
Dialogue: 0,0:08:44.17,0:08:45.88,Default,,0000,0000,0000,,So instead of drawing\Nhundreds of arrows,
Dialogue: 0,0:08:45.88,0:08:47.42,Default,,0000,0000,0000,,you could imagine\Nthat I can actually
Dialogue: 0,0:08:47.42,0:08:50.06,Default,,0000,0000,0000,,connect all these\Narrows like this
Dialogue: 0,0:08:50.06,0:08:52.48,Default,,0000,0000,0000,,and that I would have a\Nsimilar effect if I just
Dialogue: 0,0:08:52.48,0:08:53.91,Default,,0000,0000,0000,,drew it like this.
Dialogue: 0,0:08:53.91,0:08:57.04,Default,,0000,0000,0000,,I could simply draw almost\Nlike a rope or a band--
Dialogue: 0,0:08:57.04,0:09:01.29,Default,,0000,0000,0000,,imagine a band or rope\Nthat's pulling and tugging
Dialogue: 0,0:09:01.29,0:09:03.90,Default,,0000,0000,0000,,this way and this way.
Dialogue: 0,0:09:03.90,0:09:06.13,Default,,0000,0000,0000,,If I was actually to\Ndraw the band like that,
Dialogue: 0,0:09:06.13,0:09:08.28,Default,,0000,0000,0000,,you could imagine then, it\Nwould be the same effect
Dialogue: 0,0:09:08.28,0:09:11.59,Default,,0000,0000,0000,,as the hundreds of little\Nmuscles that are contracting.
Dialogue: 0,0:09:11.59,0:09:13.43,Default,,0000,0000,0000,,And to take it a\Nstep further, you
Dialogue: 0,0:09:13.43,0:09:16.44,Default,,0000,0000,0000,,could actually even imagine\Npeople yanking on that band.
Dialogue: 0,0:09:16.44,0:09:18.84,Default,,0000,0000,0000,,So this is how I\Npicture it, just
Dialogue: 0,0:09:18.84,0:09:21.30,Default,,0000,0000,0000,,people yanking on that band.
Dialogue: 0,0:09:21.30,0:09:22.72,Default,,0000,0000,0000,,These are like two\Nlittle workers,
Dialogue: 0,0:09:22.72,0:09:26.18,Default,,0000,0000,0000,,let's say, yanking on\Nthe band and pulling it
Dialogue: 0,0:09:26.18,0:09:27.52,Default,,0000,0000,0000,,in opposite directions.
Dialogue: 0,0:09:27.52,0:09:29.64,Default,,0000,0000,0000,,And if they were pulling\Nit in opposite directions,
Dialogue: 0,0:09:29.64,0:09:32.15,Default,,0000,0000,0000,,you basically have what we\Nthink of as contraction.
Dialogue: 0,0:09:32.15,0:09:33.86,Default,,0000,0000,0000,,You could have\Nlittle workers that
Dialogue: 0,0:09:33.86,0:09:37.80,Default,,0000,0000,0000,,are basically yanking on all\Nthese things, yanking away.
Dialogue: 0,0:09:37.80,0:09:40.40,Default,,0000,0000,0000,,And by yanking away, what\Nyou basically end up with
Dialogue: 0,0:09:40.40,0:09:43.38,Default,,0000,0000,0000,,is a force of contraction.
Dialogue: 0,0:09:43.38,0:09:46.10,Default,,0000,0000,0000,,So this is basically how\NI imagine contraction,
Dialogue: 0,0:09:46.10,0:09:48.62,Default,,0000,0000,0000,,having workers yanking in\Ntwo different directions.
Dialogue: 0,0:09:48.62,0:09:51.12,Default,,0000,0000,0000,,And if you had them going\Nall around the heart
Dialogue: 0,0:09:51.12,0:09:53.30,Default,,0000,0000,0000,,in every direction you\Ncould possibly imagine,
Dialogue: 0,0:09:53.30,0:09:56.27,Default,,0000,0000,0000,,that is what a contracted\Nventricle is like.
Dialogue: 0,0:09:56.27,0:09:59.23,Default,,0000,0000,0000,,And because they're\Nyanking so darn hard,
Dialogue: 0,0:09:59.23,0:10:02.11,Default,,0000,0000,0000,,because they're pulling\Nso hard on this thing,
Dialogue: 0,0:10:02.11,0:10:03.93,Default,,0000,0000,0000,,you basically have\Na lot of increase
Dialogue: 0,0:10:03.93,0:10:07.97,Default,,0000,0000,0000,,in pressure building up on the\Ninside of these ventricles.
Dialogue: 0,0:10:07.97,0:10:10.39,Default,,0000,0000,0000,,And you really don't have that\Nhappening on the other side
Dialogue: 0,0:10:10.39,0:10:13.73,Default,,0000,0000,0000,,because on the end\Ndiastolic curve--
Dialogue: 0,0:10:13.73,0:10:15.98,Default,,0000,0000,0000,,I guess the question is\Ndo we have any workers?
Dialogue: 0,0:10:15.98,0:10:16.78,Default,,0000,0000,0000,,Are they yanking?
Dialogue: 0,0:10:16.78,0:10:18.35,Default,,0000,0000,0000,,And the answer is no.
Dialogue: 0,0:10:18.35,0:10:20.86,Default,,0000,0000,0000,,The muscle cells are\Ncompletely relaxed.
Dialogue: 0,0:10:20.86,0:10:21.94,Default,,0000,0000,0000,,They're relaxed.
Dialogue: 0,0:10:21.94,0:10:25.39,Default,,0000,0000,0000,,They're just hanging\Nout and taking a nap.
Dialogue: 0,0:10:25.39,0:10:29.09,Default,,0000,0000,0000,,You can imagine your workers\Nare really not yanking at all.
Dialogue: 0,0:10:29.09,0:10:31.37,Default,,0000,0000,0000,,And as a result,\Nyou don't have any
Dialogue: 0,0:10:31.37,0:10:32.58,Default,,0000,0000,0000,,of that increase in pressure.
Dialogue: 0,0:10:32.58,0:10:35.94,Default,,0000,0000,0000,,You have just a very,\Nvery low pressure.
Dialogue: 0,0:10:35.94,0:10:37.79,Default,,0000,0000,0000,,And so that's the\Nreason you can imagine
Dialogue: 0,0:10:37.79,0:10:39.83,Default,,0000,0000,0000,,there's a difference, even\Nthough the volumes are
Dialogue: 0,0:10:39.83,0:10:42.45,Default,,0000,0000,0000,,the same, that there's a\Ndifference in pressure.
Dialogue: 0,0:10:42.45,0:10:45.01,Default,,0000,0000,0000,,So final question that plagues\Na lot of people-- and I'm
Dialogue: 0,0:10:45.01,0:10:46.84,Default,,0000,0000,0000,,actually going to make\Na little bit of space
Dialogue: 0,0:10:46.84,0:10:51.22,Default,,0000,0000,0000,,to answer it-- is so why is\Ntheir blood in the ventricles
Dialogue: 0,0:10:51.22,0:10:52.14,Default,,0000,0000,0000,,at the end of systole?
Dialogue: 0,0:10:52.14,0:10:54.91,Default,,0000,0000,0000,,I mean isn't that the point\Nwhere all of the blood
Dialogue: 0,0:10:54.91,0:10:57.60,Default,,0000,0000,0000,,has exited the ventricles\Nand gone into the aorta?
Dialogue: 0,0:10:57.60,0:10:59.22,Default,,0000,0000,0000,,Why is there any\Nblood in there anyway?
Dialogue: 0,0:10:59.22,0:11:00.99,Default,,0000,0000,0000,,Shouldn't it be empty?
Dialogue: 0,0:11:00.99,0:11:03.39,Default,,0000,0000,0000,,And to answer this--\Nto think about this,
Dialogue: 0,0:11:03.39,0:11:05.56,Default,,0000,0000,0000,,we can actually draw a\Npressure volume loop.
Dialogue: 0,0:11:05.56,0:11:07.31,Default,,0000,0000,0000,,I'm just going to\Ndraw it in purple just
Dialogue: 0,0:11:07.31,0:11:09.57,Default,,0000,0000,0000,,to create a little\Ndifference in color.
Dialogue: 0,0:11:09.57,0:11:12.26,Default,,0000,0000,0000,,And let's say that\NI have contraction
Dialogue: 0,0:11:12.26,0:11:14.23,Default,,0000,0000,0000,,right here where I\Nhave a big purple dot.
Dialogue: 0,0:11:14.23,0:11:15.97,Default,,0000,0000,0000,,That's where I begin\Nmy contraction.
Dialogue: 0,0:11:15.97,0:11:19.74,Default,,0000,0000,0000,,So I'm going to draw going\Nup from there like that.
Dialogue: 0,0:11:19.74,0:11:24.09,Default,,0000,0000,0000,,And let's say now my\Nejection is happening.
Dialogue: 0,0:11:24.09,0:11:27.86,Default,,0000,0000,0000,,And let's say, just rides\Nover my picture of the worker
Dialogue: 0,0:11:27.86,0:11:28.56,Default,,0000,0000,0000,,like that.
Dialogue: 0,0:11:28.56,0:11:32.50,Default,,0000,0000,0000,,Let me actually draw\None final volume piece,
Dialogue: 0,0:11:32.50,0:11:34.71,Default,,0000,0000,0000,,and that would be what\Nis the volume here.
Dialogue: 0,0:11:34.71,0:11:37.02,Default,,0000,0000,0000,,Because we know that the\Nvolume is not changing there,
Dialogue: 0,0:11:37.02,0:11:38.54,Default,,0000,0000,0000,,it's constant volume.
Dialogue: 0,0:11:38.54,0:11:41.49,Default,,0000,0000,0000,,And at this point,\Nyou begin ejections.
Dialogue: 0,0:11:41.49,0:11:44.24,Default,,0000,0000,0000,,So this is all ejection.
Dialogue: 0,0:11:44.24,0:11:48.37,Default,,0000,0000,0000,,I'm going to write ejection on\Nthe curvy part of the curve.
Dialogue: 0,0:11:48.37,0:11:51.95,Default,,0000,0000,0000,,So this is ejection\Nhappening right here
Dialogue: 0,0:11:51.95,0:11:53.50,Default,,0000,0000,0000,,over the hump like that.
Dialogue: 0,0:11:53.50,0:11:56.50,Default,,0000,0000,0000,,So ejection is happening\Nbetween my two white lines.
Dialogue: 0,0:11:56.50,0:12:01.50,Default,,0000,0000,0000,,And here in the vertical part, I\Ncould draw a picture like this.
Dialogue: 0,0:12:01.50,0:12:04.33,Default,,0000,0000,0000,,I could say, well, my\Nheart will be really full.
Dialogue: 0,0:12:04.33,0:12:06.68,Default,,0000,0000,0000,,So it'll look-- in fact,\Nlet me make it bigger.
Dialogue: 0,0:12:06.68,0:12:08.51,Default,,0000,0000,0000,,My heart is going to\Nbe really, really full.
Dialogue: 0,0:12:08.51,0:12:10.97,Default,,0000,0000,0000,,Let me try to\Nillustrate that nicely.
Dialogue: 0,0:12:10.97,0:12:13.08,Default,,0000,0000,0000,,So I could have\Nsomething like this.
Dialogue: 0,0:12:13.08,0:12:15.78,Default,,0000,0000,0000,,I could have\Nsomething like that.
Dialogue: 0,0:12:15.78,0:12:19.74,Default,,0000,0000,0000,,And if my ventricle is that\Nbig, if it's that large-- let
Dialogue: 0,0:12:19.74,0:12:21.78,Default,,0000,0000,0000,,me actually just\Ncolor it in now.
Dialogue: 0,0:12:21.78,0:12:25.36,Default,,0000,0000,0000,,Then what's actually happening\Nwhen I have ejection?
Dialogue: 0,0:12:25.36,0:12:29.25,Default,,0000,0000,0000,,Well, I'm going to cut\Nand paste this little guy,
Dialogue: 0,0:12:29.25,0:12:33.58,Default,,0000,0000,0000,,and show you on the top\Nwhat it would look like.
Dialogue: 0,0:12:33.58,0:12:36.41,Default,,0000,0000,0000,,So let me just drag this\Nlittle fella over here.
Dialogue: 0,0:12:36.41,0:12:41.11,Default,,0000,0000,0000,,And now this, if this\Nis how I start out,
Dialogue: 0,0:12:41.11,0:12:43.71,Default,,0000,0000,0000,,then when I eject\Nblood, you're basically
Dialogue: 0,0:12:43.71,0:12:45.13,Default,,0000,0000,0000,,going to have\Nsomething like this.
Dialogue: 0,0:12:45.13,0:12:49.21,Default,,0000,0000,0000,,You're going to have an\Namount that goes away,
Dialogue: 0,0:12:49.21,0:12:50.82,Default,,0000,0000,0000,,and an amount\Nthat's left behind.
Dialogue: 0,0:12:50.82,0:12:54.03,Default,,0000,0000,0000,,So the amount that's left\Nbehind is, of course, the amount
Dialogue: 0,0:12:54.03,0:12:57.58,Default,,0000,0000,0000,,that I showed you on the side.
Dialogue: 0,0:12:57.58,0:12:58.88,Default,,0000,0000,0000,,And I'm cutting it out.
Dialogue: 0,0:12:58.88,0:13:01.08,Default,,0000,0000,0000,,And this doughnut hole\Nshape that's left,
Dialogue: 0,0:13:01.08,0:13:03.62,Default,,0000,0000,0000,,this is actually\Nour stroke volume.
Dialogue: 0,0:13:03.62,0:13:05.81,Default,,0000,0000,0000,,This is our stroke volume.
Dialogue: 0,0:13:05.81,0:13:08.93,Default,,0000,0000,0000,,So you actually do have a lot of\Nblood that goes into the aorta.
Dialogue: 0,0:13:08.93,0:13:11.34,Default,,0000,0000,0000,,Of course, that's important.
Dialogue: 0,0:13:11.34,0:13:13.69,Default,,0000,0000,0000,,And you have a little\Nchunk that's left.
Dialogue: 0,0:13:13.69,0:13:18.22,Default,,0000,0000,0000,,So now you can see that at\Nthe beginning of contraction,
Dialogue: 0,0:13:18.22,0:13:21.45,Default,,0000,0000,0000,,you end up with having\Na lot of blood here.
Dialogue: 0,0:13:21.45,0:13:23.22,Default,,0000,0000,0000,,This is where you start.
Dialogue: 0,0:13:23.22,0:13:25.21,Default,,0000,0000,0000,,And then you lose\Na lot of blood.
Dialogue: 0,0:13:25.21,0:13:27.07,Default,,0000,0000,0000,,This is our stroke\Nvolume that you lose.
Dialogue: 0,0:13:27.07,0:13:29.66,Default,,0000,0000,0000,,And then you are left with\Na little bit of blood here.
Dialogue: 0,0:13:29.66,0:13:32.54,Default,,0000,0000,0000,,And that's at the end of\Nsystole So at the end of systole
Dialogue: 0,0:13:32.54,0:13:35.51,Default,,0000,0000,0000,,you do have some blood left, but\Nyou don't have nearly as much
Dialogue: 0,0:13:35.51,0:13:38.52,Default,,0000,0000,0000,,as you had when\Nyou began systole.