WEBVTT 00:00:01.940 --> 00:00:05.190 So we've talked a little bit about the lungs and the tissue, 00:00:05.190 --> 00:00:08.430 and how there's an interesting relationship between the two 00:00:08.430 --> 00:00:12.490 where they're trying to send little molecules back 00:00:12.490 --> 00:00:13.010 and forth. 00:00:13.010 --> 00:00:16.079 The lungs are trying to send, of course, oxygen out 00:00:16.079 --> 00:00:17.800 to the tissues. 00:00:17.800 --> 00:00:19.780 And the tissues are trying to figure out 00:00:19.780 --> 00:00:23.200 a way to efficiently send back carbon dioxide. 00:00:23.200 --> 00:00:25.505 So these are the core things that 00:00:25.505 --> 00:00:27.080 are going on between the two. 00:00:27.080 --> 00:00:29.080 And remember, in terms of getting oxygen across, 00:00:29.080 --> 00:00:31.060 there are two major ways, we said. 00:00:31.060 --> 00:00:35.590 The first one, the easy one is just dissolved oxygen, 00:00:35.590 --> 00:00:38.240 dissolved oxygen in the blood itself. 00:00:38.240 --> 00:00:39.580 But that's not the major way. 00:00:39.580 --> 00:00:43.130 The major way is when oxygen actually binds hemoglobin. 00:00:43.130 --> 00:00:45.750 In fact, we call that HbO2. 00:00:45.750 --> 00:00:49.630 And the name of that molecule is oxyhemoglobin. 00:00:49.630 --> 00:00:52.400 So this is how the majority of the oxygen 00:00:52.400 --> 00:00:55.130 is going to get delivered to the tissues. 00:00:55.130 --> 00:00:57.730 And on the other side, coming back from the tissue 00:00:57.730 --> 00:01:00.597 to the lungs, you've got dissolved carbon dioxide. 00:01:00.597 --> 00:01:02.680 A little bit of carbon dioxide actually, literally 00:01:02.680 --> 00:01:05.430 comes just right in the plasma. 00:01:05.430 --> 00:01:08.650 But that's not the majority of how carbon dioxide gets back. 00:01:08.650 --> 00:01:12.260 The more effective ways of getting carbon dioxide back, 00:01:12.260 --> 00:01:15.760 remember, we have this protonated hemoglobin. 00:01:15.760 --> 00:01:17.490 And actually remember, when I say 00:01:17.490 --> 00:01:19.190 there's a proton on the hemoglobin, 00:01:19.190 --> 00:01:22.970 there's got to be some bicarb floating around in the plasma. 00:01:22.970 --> 00:01:25.640 And the reason that works is because when they get back 00:01:25.640 --> 00:01:29.640 to the lungs, the proton, that bicarb, actually meet up again. 00:01:29.640 --> 00:01:32.840 And they form CO2 and water. 00:01:32.840 --> 00:01:35.430 And this happens because there's an enzyme called 00:01:35.430 --> 00:01:38.530 carbonic anhydrase inside of the red blood cells. 00:01:38.530 --> 00:01:41.692 So this is where the carbon dioxide actually gets back. 00:01:41.692 --> 00:01:43.150 And of course, there's a third way. 00:01:43.150 --> 00:01:44.960 Remember, there's also some hemoglobin 00:01:44.960 --> 00:01:49.320 that actually binds directly to carbon dioxide. 00:01:49.320 --> 00:01:52.970 And in the process, it forms a little proton as well. 00:01:52.970 --> 00:01:56.190 And that proton can go do this business. 00:01:56.190 --> 00:01:58.400 It can bind to a hemoglobin as well. 00:01:58.400 --> 00:02:01.780 So there's a little interplay there. 00:02:01.780 --> 00:02:04.390 But the important ones I want you to really kind of focus in 00:02:04.390 --> 00:02:08.560 on are the fact that hemoglobin can bind to oxygen. 00:02:08.560 --> 00:02:11.390 And also on this side, that hemoglobin 00:02:11.390 --> 00:02:13.800 actually can bind to protons. 00:02:13.800 --> 00:02:15.380 Now, the fun part about all this is 00:02:15.380 --> 00:02:16.796 that there's a little competition, 00:02:16.796 --> 00:02:18.800 a little game going on here. 00:02:18.800 --> 00:02:20.710 Because you've got, on the one side, 00:02:20.710 --> 00:02:24.320 you've got hemoglobin binding oxygen. 00:02:24.320 --> 00:02:26.900 And let me draw it twice. 00:02:26.900 --> 00:02:29.800 And let's say this top one interacts with a proton. 00:02:29.800 --> 00:02:34.540 Well, that protons going to want to snatch away the hemoglobin. 00:02:34.540 --> 00:02:36.830 And so there's a little competition for hemoglobin. 00:02:36.830 --> 00:02:40.100 And here, the oxygen gets left out in the cold. 00:02:40.100 --> 00:02:43.300 And the carbon dioxide does the same thing, we said. 00:02:43.300 --> 00:02:46.630 Now, we have little hemoglobin bound to carbon dioxide. 00:02:46.630 --> 00:02:49.240 And it makes a proton in the process. 00:02:49.240 --> 00:02:52.330 But again, it leave oxygen out in the cold. 00:02:52.330 --> 00:02:54.700 So depending on whether you have a lot of oxygen 00:02:54.700 --> 00:02:58.010 around, if that's the kind of key thing going on, 00:02:58.010 --> 00:03:01.210 or whether you have a lot of these kinds of products 00:03:01.210 --> 00:03:03.760 the proton or the carbon dioxide. 00:03:03.760 --> 00:03:07.050 Depending on which one you have more of floating around 00:03:07.050 --> 00:03:10.200 in the tissue in the cell, will determine 00:03:10.200 --> 00:03:11.776 which way that reaction goes. 00:03:11.776 --> 00:03:13.400 So keeping this concept in mind, then I 00:03:13.400 --> 00:03:15.380 could actually step back and say, well, 00:03:15.380 --> 00:03:20.045 I think that oxygen is affected by carbon dioxide and protons. 00:03:20.045 --> 00:03:22.420 I could say, well, these two, carbon dioxide and protons, 00:03:22.420 --> 00:03:25.440 are actually affecting, let's say, 00:03:25.440 --> 00:03:36.180 are affecting the, let's say, the affinity or the willingness 00:03:36.180 --> 00:03:41.620 of hemoglobin to bind, of hemoglobin for oxygen. 00:03:41.620 --> 00:03:43.880 That's one kind of statement you could 00:03:43.880 --> 00:03:46.430 make by looking at that kind of competition. 00:03:46.430 --> 00:03:48.250 And another person come along and they say, 00:03:48.250 --> 00:03:52.420 well, I think oxygen actually is affecting, 00:03:52.420 --> 00:03:54.880 depending on which one, which perspective you take. 00:03:54.880 --> 00:03:57.450 You could say, oxygen is affecting maybe the affinity 00:03:57.450 --> 00:04:03.530 of hemoglobin for the carbon dioxide and proton 00:04:03.530 --> 00:04:09.700 of hemoglobin for CO2 and protons. 00:04:09.700 --> 00:04:13.110 So you could say it from either perspective. 00:04:13.110 --> 00:04:15.230 And what I want to point out is that actually, 00:04:15.230 --> 00:04:17.426 in a sense, both of these are true. 00:04:17.426 --> 00:04:19.300 And a lot of times we think, well, maybe it's 00:04:19.300 --> 00:04:21.350 just saying the same thing twice. 00:04:21.350 --> 00:04:23.730 But actually, these are two separate effects. 00:04:23.730 --> 00:04:25.130 And they have two separate names. 00:04:25.130 --> 00:04:29.650 So the first one, talking about carbon dioxide and protons, 00:04:29.650 --> 00:04:32.840 their effect is called the Bohr effect. 00:04:32.840 --> 00:04:36.230 So you might see that word or this description. 00:04:36.230 --> 00:04:38.020 This is the Bohr effect. 00:04:38.020 --> 00:04:41.170 And the other one, looking at it from the other prospective, 00:04:41.170 --> 00:04:43.210 looking at it from oxygen's perspective, 00:04:43.210 --> 00:04:45.430 this would be the Haldane effect. 00:04:45.430 --> 00:04:48.480 That's just the name of it, Haldane effect. 00:04:48.480 --> 00:04:50.770 So what is the Bohr effect and the Haldane effect? 00:04:50.770 --> 00:04:53.660 Other than simply saying that the things compete 00:04:53.660 --> 00:04:54.744 for hemoglobin. 00:04:54.744 --> 00:04:57.160 Well, let me actually bring up a little bit of the canvas. 00:04:57.160 --> 00:04:59.460 And let's see if I can't diagram this out. 00:04:59.460 --> 00:05:01.770 Because sometimes I think a little diagram would really 00:05:01.770 --> 00:05:03.530 go a long way in explaining these things. 00:05:03.530 --> 00:05:05.770 So let's see if I can do that. 00:05:05.770 --> 00:05:09.150 Let's use a little graph and see if we can illustrate the Bohr 00:05:09.150 --> 00:05:10.710 effect on this graph. 00:05:10.710 --> 00:05:13.010 So this is the partial pressure of oxygen, 00:05:13.010 --> 00:05:15.710 how much is dissolved in the plasma. 00:05:15.710 --> 00:05:18.610 And this is oxygen content, which is to say, 00:05:18.610 --> 00:05:21.076 how much total oxygen is there in the blood. 00:05:21.076 --> 00:05:22.700 And this, of course, takes into account 00:05:22.700 --> 00:05:26.950 mostly the amount of oxygen that's bound to hemoglobin. 00:05:26.950 --> 00:05:30.690 So as I slowly increase the partial pressure of oxygen, 00:05:30.690 --> 00:05:33.750 see how initially, not too much is 00:05:33.750 --> 00:05:36.630 going to be binding to the hemoglobin. 00:05:36.630 --> 00:05:39.170 But eventually as a few of the molecules bind, 00:05:39.170 --> 00:05:40.830 you get cooperativity. 00:05:40.830 --> 00:05:44.170 And so then, slowly the slope starts to rise. 00:05:44.170 --> 00:05:45.840 And it becomes more steep. 00:05:45.840 --> 00:05:47.680 And this is all because of cooperativity. 00:05:47.680 --> 00:05:51.550 Oxygen likes to bind where other oxygens have already bound. 00:05:51.550 --> 00:05:54.490 , And then it's going to level off. 00:05:54.490 --> 00:05:56.460 And the leveling off is because hemoglobin 00:05:56.460 --> 00:05:58.170 is starting to get saturated. 00:05:58.170 --> 00:06:00.280 So there aren't too many extra spots available. 00:06:00.280 --> 00:06:03.500 So you need lots and lots of oxygen dissolved in the plasma 00:06:03.500 --> 00:06:06.910 to be able to seek out and find those extra remaining 00:06:06.910 --> 00:06:09.040 spots on hemoglobin. 00:06:09.040 --> 00:06:10.590 So let's say we choose two spots. 00:06:10.590 --> 00:06:12.680 One spot, let's say, is a high amount 00:06:12.680 --> 00:06:16.150 of oxygen dissolved in the blood. 00:06:16.150 --> 00:06:17.735 And this, let's say, is a low amount 00:06:17.735 --> 00:06:19.110 of oxygen dissolved in the blood. 00:06:19.110 --> 00:06:20.901 I'm just kind of choosing them arbitrarily. 00:06:20.901 --> 00:06:23.300 And don't worry about the units. 00:06:23.300 --> 00:06:25.300 And if you were to think of where in the body 00:06:25.300 --> 00:06:27.055 would be a high location, that could 00:06:27.055 --> 00:06:28.430 be something like the lungs where 00:06:28.430 --> 00:06:31.260 you have a lot of oxygen dissolved in blood. 00:06:31.260 --> 00:06:35.290 And low would be, let's say, the thigh muscle where there's 00:06:35.290 --> 00:06:39.080 a lot of CO2 but not so much oxygen dissolved in the blood. 00:06:39.080 --> 00:06:41.240 So this could be two parts of our body. 00:06:41.240 --> 00:06:42.570 And you can see that. 00:06:42.570 --> 00:06:45.340 Now, if I want to figure out, looking at this curve 00:06:45.340 --> 00:06:49.166 how much oxygen is being delivered to the thigh, 00:06:49.166 --> 00:06:50.540 then that's actually pretty easy. 00:06:50.540 --> 00:06:54.870 I could just say, well, how much oxygen was there in the lungs, 00:06:54.870 --> 00:06:57.420 or in the blood vessels that are leaving the lungs. 00:06:57.420 --> 00:06:59.130 And there's this much oxygen in the blood 00:06:59.130 --> 00:07:01.120 vessels leaving the lungs. 00:07:01.120 --> 00:07:03.830 And there's this much oxygen in the blood 00:07:03.830 --> 00:07:05.950 vessels leaving the thigh. 00:07:05.950 --> 00:07:11.710 So the difference, whenever oxygen is between these two 00:07:11.710 --> 00:07:14.754 points, that's the amount of oxygen that got delivered. 00:07:14.754 --> 00:07:17.170 So if you want to figure out how much oxygen got delivered 00:07:17.170 --> 00:07:22.050 to any tissue you can simply subtract these two values. 00:07:22.050 --> 00:07:23.590 So that's the oxygen delivery. 00:07:23.590 --> 00:07:26.400 But looking at this, you can see an interesting point 00:07:26.400 --> 00:07:29.220 which is that if you wanted to increase the oxygen delivery. 00:07:29.220 --> 00:07:31.320 Let's say, you wanted for some reason 00:07:31.320 --> 00:07:35.600 to increase it, become more efficient, then really, 00:07:35.600 --> 00:07:37.590 the only way to do that is to have 00:07:37.590 --> 00:07:41.510 the thigh become more hypoxic. 00:07:41.510 --> 00:07:43.580 As you move to the left on here, that's 00:07:43.580 --> 00:07:47.600 really becoming hypoxic, or having less oxygen. 00:07:47.600 --> 00:07:52.010 So if you become more hypoxic, then, yes, you'll 00:07:52.010 --> 00:07:56.700 have maybe a lower point here, maybe a point like this. 00:07:56.700 --> 00:07:59.650 And that would mean a larger oxygen delivery. 00:07:59.650 --> 00:08:00.820 But that's not ideal. 00:08:00.820 --> 00:08:03.410 You don't want your thighs to become hypoxic. 00:08:03.410 --> 00:08:05.980 That could start aching and hurting. 00:08:05.980 --> 00:08:09.760 So is there another way to have a large oxygen delivery 00:08:09.760 --> 00:08:13.050 without having any hypoxic tissue, 00:08:13.050 --> 00:08:15.560 or tissue that has a low amount of oxygen in it. 00:08:15.560 --> 00:08:17.650 And this is where the Bohr effect comes into play. 00:08:17.650 --> 00:08:19.200 So remember, the Bohr effect said 00:08:19.200 --> 00:08:23.500 that, CO2 and protons affect the hemoglobin's 00:08:23.500 --> 00:08:25.470 affinity for oxygen. 00:08:25.470 --> 00:08:28.640 So let's think of a situation. 00:08:28.640 --> 00:08:30.049 I'll do it in green. 00:08:30.049 --> 00:08:32.590 And in this situation, where you have a lot of carbon dioxide 00:08:32.590 --> 00:08:34.590 and protons, the Bohr effect tells us 00:08:34.590 --> 00:08:37.620 that it's going to be harder for oxygen to bind hemoglobin. 00:08:37.620 --> 00:08:40.220 So if I was to sketch out another curve, 00:08:40.220 --> 00:08:43.940 initially, it's going to be even less impressive, 00:08:43.940 --> 00:08:46.590 with less oxygen bound to hemoglobin. 00:08:46.590 --> 00:08:49.760 And eventually, once the concentration of oxygen 00:08:49.760 --> 00:08:53.070 rises enough, it will start going up, up, up. 00:08:53.070 --> 00:08:55.040 And it does bind hemoglobin eventually. 00:08:55.040 --> 00:08:57.000 So it's not like it'll never bind hemoglobin 00:08:57.000 --> 00:08:59.710 in the presence of carbon dioxide and protons. 00:08:59.710 --> 00:09:01.770 But it takes longer. 00:09:01.770 --> 00:09:05.355 And so the entire curve looks shifted over. 00:09:05.355 --> 00:09:09.340 These conditions of high CO2 and high protons, 00:09:09.340 --> 00:09:11.620 that's not really relevant to the lungs. 00:09:11.620 --> 00:09:14.540 The lungs are thinking, well, for us, who cares. 00:09:14.540 --> 00:09:16.450 We don't really have these conditions. 00:09:16.450 --> 00:09:18.890 But for the thigh, it is relevant 00:09:18.890 --> 00:09:20.960 because the thigh has a lot of CO2. 00:09:20.960 --> 00:09:23.050 And the thigh has a lot of protons. 00:09:23.050 --> 00:09:26.170 Again, remember, high protons means low pH. 00:09:26.170 --> 00:09:29.420 So you can think of it either way. 00:09:29.420 --> 00:09:33.190 So in the thigh, you're going to get, then, a different point. 00:09:33.190 --> 00:09:36.720 It's going to be on the green curve not the blue curve. 00:09:36.720 --> 00:09:40.310 So we can draw it at the same O2 level, 00:09:40.310 --> 00:09:42.230 actually being down here. 00:09:42.230 --> 00:09:45.750 So what is the O2 content in the blood that's leaving the thigh? 00:09:45.750 --> 00:09:47.960 Well, then to do it properly, I would say, well, 00:09:47.960 --> 00:09:50.530 it would actually be over here. 00:09:50.530 --> 00:09:52.420 This is the actual amount. 00:09:52.420 --> 00:09:56.290 And so O2 deliver is actually much more impressive. 00:09:56.290 --> 00:09:57.360 Look at that. 00:09:57.360 --> 00:10:01.127 So O2 delivery is increased because of the Bohr effect. 00:10:01.127 --> 00:10:03.460 And if you want to know exactly how much it's increased, 00:10:03.460 --> 00:10:04.410 I could even show you. 00:10:04.410 --> 00:10:08.830 I could say, well, this amount from here down to here. 00:10:08.830 --> 00:10:11.820 Literally the vertical distance between the green 00:10:11.820 --> 00:10:13.040 and the blue lines. 00:10:13.040 --> 00:10:17.650 So this is the extra oxygen delivered because of the Bohr 00:10:17.650 --> 00:10:19.050 effect. 00:10:19.050 --> 00:10:22.670 So this is how the Bohr effect is so important at actually 00:10:22.670 --> 00:10:25.710 helping us deliver oxygen to our tissues. 00:10:25.710 --> 00:10:28.710 So let's do the same thing, now, but for the Haldane effect. 00:10:28.710 --> 00:10:31.120 And to do this, we actually have to switch things around. 00:10:31.120 --> 00:10:34.050 So our units and our axes are going to be different. 00:10:34.050 --> 00:10:37.770 So we're going to have the amount of carbon dioxide there. 00:10:37.770 --> 00:10:41.490 And here, we'll do carbon dioxide content in the blood. 00:10:41.490 --> 00:10:43.880 So let's think through this carefully. 00:10:43.880 --> 00:10:45.930 Let's first start out with increasing 00:10:45.930 --> 00:10:48.670 the amount of carbon dioxide slowly but surely. 00:10:48.670 --> 00:10:50.830 And see how the content goes up. 00:10:50.830 --> 00:10:53.600 And here, as you increase the amount of carbon dioxide, 00:10:53.600 --> 00:10:56.529 the content is kind of goes up as a straight line. 00:10:56.529 --> 00:10:58.070 And the reason it doesn't take that S 00:10:58.070 --> 00:10:59.960 shape that we had with the oxygen 00:10:59.960 --> 00:11:03.220 is that there's no cooperativity in binding the hemoglobin. 00:11:03.220 --> 00:11:05.710 It just goes up straight. 00:11:05.710 --> 00:11:07.400 So that's easy enough. 00:11:07.400 --> 00:11:10.010 Now, let's take two points like we did before. 00:11:10.010 --> 00:11:11.840 Let's take a point, let's say up here. 00:11:11.840 --> 00:11:15.040 This will be a high amount of CO2 in the blood. 00:11:15.040 --> 00:11:18.220 And this will be a low amount of CO2 in the blood. 00:11:18.220 --> 00:11:20.540 So you'd have a low amount, let's say right here, 00:11:20.540 --> 00:11:22.630 in what part of the tissue? 00:11:22.630 --> 00:11:25.780 Well, low CO2, that sounds like the lungs 00:11:25.780 --> 00:11:28.500 because there's not too much CO2 there. 00:11:28.500 --> 00:11:31.750 But high CO2, it probably is the thighs 00:11:31.750 --> 00:11:35.080 because the thighs like little CO2 factories. 00:11:35.080 --> 00:11:38.330 So the thigh has a high amount and the lungs 00:11:38.330 --> 00:11:39.080 have a low amount. 00:11:39.080 --> 00:11:42.850 So if I want to look at the amount of CO2 delivered, 00:11:42.850 --> 00:11:43.850 we'd do it the same way. 00:11:43.850 --> 00:11:47.340 We say, OK, well, the thighs had a high amount. 00:11:47.340 --> 00:11:50.990 And this is the amount of CO2 in the blood, remember. 00:11:50.990 --> 00:11:53.120 And this is the amount of CO2 in the blood when 00:11:53.120 --> 00:11:54.780 it gets to the lungs. 00:11:54.780 --> 00:11:59.270 So the amount of CO2 that was delivered from the thigh 00:11:59.270 --> 00:12:01.860 to the lungs is the difference. 00:12:01.860 --> 00:12:04.250 And so this is how much CO2 delivery 00:12:04.250 --> 00:12:05.670 we're actually getting. 00:12:05.670 --> 00:12:10.560 So just like we had O2 delivery, we have this much CO2 delivery. 00:12:10.560 --> 00:12:12.640 Now, read over the Haldane effect. 00:12:12.640 --> 00:12:16.390 And let's see if we can actually sketch out another line. 00:12:16.390 --> 00:12:20.670 In the presence of high oxygen, what's going to happen? 00:12:20.670 --> 00:12:23.270 Well, if there's a lot of oxygen around, 00:12:23.270 --> 00:12:26.650 then it's going to change the affinity of hemoglobin 00:12:26.650 --> 00:12:28.960 for carbon dioxide and protons. 00:12:28.960 --> 00:12:34.500 So it's going to allow less binding of protons and carbon 00:12:34.500 --> 00:12:36.809 dioxide directly to the hemoglobin. 00:12:36.809 --> 00:12:38.850 And that means that you're going to have less CO2 00:12:38.850 --> 00:12:44.410 content for any given amount of dissolved CO2 in the blood. 00:12:44.410 --> 00:12:47.180 So the line still is a straight line, but it's actually, 00:12:47.180 --> 00:12:50.240 you notice, it's kind of slope downwards. 00:12:50.240 --> 00:12:52.820 So where is this relevant? 00:12:52.820 --> 00:12:54.250 Where do you have a lot of oxygen? 00:12:54.250 --> 00:12:56.900 Well, it's not really relevant for the thighs 00:12:56.900 --> 00:12:59.370 because the thighs don't have a lot of oxygen. 00:12:59.370 --> 00:13:01.990 But it is relevant for the lungs. 00:13:01.990 --> 00:13:03.950 It is very relevant there. 00:13:03.950 --> 00:13:07.640 So now you can actually say, well, let's see what happens. 00:13:07.640 --> 00:13:10.970 Now that you have high O2, how much CO2 delivery 00:13:10.970 --> 00:13:12.140 are you getting? 00:13:12.140 --> 00:13:14.160 And you can already see it. 00:13:14.160 --> 00:13:17.260 It's going to be more because now you've got this much. 00:13:17.260 --> 00:13:21.290 You've got going all the way over here. 00:13:21.290 --> 00:13:23.650 So this is the new amount of CO2 delivery. 00:13:23.650 --> 00:13:24.770 And it's gone up. 00:13:24.770 --> 00:13:27.400 And in fact, you can even show exactly how much 00:13:27.400 --> 00:13:30.010 it's gone up by, by simply taking this difference. 00:13:30.010 --> 00:13:33.470 So this difference right here between the two, 00:13:33.470 --> 00:13:36.280 this is the Haldane effect. 00:13:36.280 --> 00:13:38.900 This is the visual way that you can actually 00:13:38.900 --> 00:13:40.880 see that Haldane effect. 00:13:40.880 --> 00:13:42.880 So the Bohr effect and the Haldane effect, these 00:13:42.880 --> 00:13:45.940 are two important strategies our body 00:13:45.940 --> 00:13:49.720 has for increasing the amount of O2 delivery and CO2 00:13:49.720 --> 00:13:51.770 delivery going back and forth between the lungs 00:13:51.770 --> 00:13:53.460 and the tissues.