This was a graph in the Kap's FL 4. Can someone help me understand what's going on? Also, does someone have any tips on deciphering a graph like this.
All it says is: Figure 1 shows that at 60 mmHg, the hemoglobin is still around 90% saturated.
Reading Physio Graphs
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This was a graph in the Kap's FL 4. Can someone help me understand what's going on? Also, does someone have any tips on deciphering a graph like this.
All it says is: Figure 1 shows that at 60 mmHg, the hemoglobin is still around 90% saturated.
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Kind of depends on what the question is about.
But basically, iirc, the curve of oxygen in hemoglobin is a sigmoidal one, meaning as O2 conc in the blood goes up, hemoglobin gets more and more saturated with O2. But it reaches a limit, and gets there slower and slower. Initially it's very fast, because Hb gobbles up O2 as its not bonded with any.
Doesnt Hb get better association with O2 after the first molecule of O is bonded to Hb?
But basically, iirc, the curve of oxygen in hemoglobin is a sigmoidal one, meaning as O2 conc in the blood goes up, hemoglobin gets more and more saturated with O2. But it reaches a limit, and gets there slower and slower. Initially it's very fast, because Hb gobbles up O2 as its not bonded with any.
Doesnt Hb get better association with O2 after the first molecule of O is bonded to Hb?
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I don't get what you mean. It shows how saturated hemoglobin molecules in your blood are with O2 vs. the partial pressure of O2 in your blood.
On the far left where there is 0 oxygen dissolved in your blood, none of the hemoglobins are holding O2 either. They give it up when free O2 is low and bind it when free O2 is high.
You can see from the middle section that the hemoglobins saturate quickly as you increase the pressure of O2 in the blood, and then in the last section (40mmHg and up) it tails off. That sigmoidal shape is due to allosteric effects and allows hemoglobin to dump off O2 when tissues need it.
EDIT looks like Khan has a vid on hemoglobin. My rule of thumb is if he has a video on something you need to know, I'm gonna watch it. Not sure if he goes over the graph though. I've never seen this one.
http://www.khanacademy.org/science/biology/v/hemoglobin
Doubledit- he does
On the far left where there is 0 oxygen dissolved in your blood, none of the hemoglobins are holding O2 either. They give it up when free O2 is low and bind it when free O2 is high.
You can see from the middle section that the hemoglobins saturate quickly as you increase the pressure of O2 in the blood, and then in the last section (40mmHg and up) it tails off. That sigmoidal shape is due to allosteric effects and allows hemoglobin to dump off O2 when tissues need it.
EDIT looks like Khan has a vid on hemoglobin. My rule of thumb is if he has a video on something you need to know, I'm gonna watch it. Not sure if he goes over the graph though. I've never seen this one.
http://www.khanacademy.org/science/biology/v/hemoglobin
Doubledit- he does
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You mean on the left? Volume of total oxygen in blood over total volume of blood I think. As in when every hemoglobin is carrying an oxygen (or I guess 4 since 4 subunits), there will by 20mL of oxygen in 100mL of blood. But obviously the volume isn't that great because it gets bound to hemoglobin, but it was in the air and will be when it turns to gas again.
According to the graph in Figure 1, under normal conditions, the body's tissues utilize approximately:
75% of the oxygen bound to Hb.
75% of the oxygen transported in the blood (in solution and bound to Hb).
50% of the oxygen transported in the blood (in solution and bound to Hb).
25% of the oxygen bound to Hb.
75% of the oxygen bound to Hb.
75% of the oxygen transported in the blood (in solution and bound to Hb).
50% of the oxygen transported in the blood (in solution and bound to Hb).
25% of the oxygen bound to Hb.
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Exchange happens in the capillaries, so it should be the % difference between arteries and veins. Is it 25%?
You're right! Can you please elaborate when you say "exchange happens". I TOTALLY missed that the amount of blood the tissues utilize is represented by the difference in Hb saturation between arterial and venous blood.
Would choice B (or C be correct) if it said:
3% of the oxygen transported in the blood (in solution and bound to Hb).
Would choice B (or C be correct) if it said:
3% of the oxygen transported in the blood (in solution and bound to Hb).
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In the systematic circulation, your heart gets oxygenated blood from the lungs and then it pumps it out through the arteries, then it goes through the arterioles, then the capllaries, which are only a cell thick. In the capillaries, the blood is moving really slowly and ions, gases, etc can diffuse (or get carried) through the blood cells, through the walls and into the cells of your body that need to dump off wastes and get stuff like sugar and oxygen.
Then it leaves the capillaries carrying less oxygen, less sugar, all that kind of crap, and more carbon dioxide (as carbonic acid), urea, etc. so when it gets to the veins it has that difference in what it's carrying.
As for your question, I think you're slightly off in what the 3% represents (it looks like 5% to me- from 14% to 19%). That scale is saying, if I'm reading it correctly that blood in the veins is 14% oxygen by volume and in the arteries it's 19% oxygen by volume. That's not the same thing 14% or 19% of the oxygen transported by the blood. The percent transported by the blood is 19-14/20 = 25%- the same answer as if you're going by % Hb saturation. Remember that more or less all the oxygen in your blood is carried by hemoglobin. The amount that's just diffused in the plasma is negligible.
Make sure you are reading through an MCAT bio book on these physio topics. There is a lot of stuff you need to know. It's manageable and usually the principles will make sense and make it easy to remember, but you need to know reproduction, respiratory, circulatory, etc for the MCAT.
Then it leaves the capillaries carrying less oxygen, less sugar, all that kind of crap, and more carbon dioxide (as carbonic acid), urea, etc. so when it gets to the veins it has that difference in what it's carrying.
As for your question, I think you're slightly off in what the 3% represents (it looks like 5% to me- from 14% to 19%). That scale is saying, if I'm reading it correctly that blood in the veins is 14% oxygen by volume and in the arteries it's 19% oxygen by volume. That's not the same thing 14% or 19% of the oxygen transported by the blood. The percent transported by the blood is 19-14/20 = 25%- the same answer as if you're going by % Hb saturation. Remember that more or less all the oxygen in your blood is carried by hemoglobin. The amount that's just diffused in the plasma is negligible.
Make sure you are reading through an MCAT bio book on these physio topics. There is a lot of stuff you need to know. It's manageable and usually the principles will make sense and make it easy to remember, but you need to know reproduction, respiratory, circulatory, etc for the MCAT.
Capillaries serve as the exchange for tissues, so yeah. Arterioles and arteries are too thick, with their smooth muscle, to facilitate exchange of CO2 and nutrients across the simple squamous endothelial layer of the capillaries.
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aw shucks I got to brush up on my physio: circ, nervous, endo, repro, GI, basically everything...😱
oh lawd i just sent in my TBR order👍
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If you still have Vander's or something like that from college, it wouldn't hurt to read through it. Khan has decent videos to watch on a bunch of physio topics as well, although obviously not enough to use as a main source for the MCAT.
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The good news is there is a good amount of overlap between physio and molecular bio/biochem in terms of the 3 and 400 level courses. Physio is more rote memorization, unfortunately.
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This was a graph in the Kap's FL 4. Can someone help me understand what's going on? Also, does someone have any tips on deciphering a graph like this.
All it says is: Figure 1 shows that at 60 mmHg, the hemoglobin is still around 90% saturated.
The figure is a saturation curve for hb occuring at 5 points: 1%, 9%, 50%, 90% and 99%. The 50% is the KD (rate of disassociation) , where 50% of hb is now bound to O2, which is at P02 of 40mmHg. Where as at 99% is where when 99% of hb has bound O2 and cannot bind anymore O2. The saturation can be graphed in either binding affinity, or # of binding site of ligand (Oxy). In this case, it is in terms of # of binding sites. Hope this helps!!!
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Also the khan guy for the hemo vid says there are 20-30 TRILLION rbcs in our body?
I was told that our body has about 20-30 trillion CELLS, and that rbc's are only about 2-5 trillion depending on body size?
Or can you have 20-30 trillion rbcs in our blood that don't get counted in the body cell count?
This is not MCAT related..
I was told that our body has about 20-30 trillion CELLS, and that rbc's are only about 2-5 trillion depending on body size?
Or can you have 20-30 trillion rbcs in our blood that don't get counted in the body cell count?
This is not MCAT related..
