Partial pressures of gases in the atmosphere, alveoli, and blood stream. What partial pressures mean, and how gases diffuse into and are carried by the blood stream.
Yes, thank you. The way I understand it- the partial pressure will be higher where the concentration of gas is higher, and it will be lower where the concentration is lower. So either way, the driving force for oxygen to move across the membrane can be referred to as the partial pressure difference or the concentration difference... Correct?
The diffusion coefficient (Krogh) of CO2 is 20 times that of water across this membrane. Solubility of CO2 in water is 24 times higher than oxygen, but the molecule of CO2 is a little larger than O2 so the diffusion factor works out to 20 times that, not 5.
Once again, another great video! I'm very grateful to you for putting these up here! One question- it seems as though the terms "concentration gradient" and "partial pressure" are being used interchangeably throughout the video... is this correct? O2 moves down its concentration gradient; or O2 moves to where the partial pressure is lower...? To phrase my question another way: is the driving force for O2 the difference in pressure across the membrane or the difference in concentration?
I am hoping you would clarify and correct something in your video. You show the CO2 diffusing into the blood.however, as I understand it the partial pressure of carbon dioxide is higher in the capillary bed and therefore should diffuse into the lungs to be expelled.
Yes, that should have been drawn the other way around. Obviously the CO2 from metabolism is breathed out, so the bicarbonate is high in the venous blood, and leaves the cell as CO2 and crosses the wall into the alveoles to be breathed out..
You imply that both CO2 and O2 coexist on Hgb molecules. In fact, they compete for sites on hemoglobin. Also, carboxyhemoglobin is a heme molecule carrying CO, not CO2. CO has a much higher affinity for Hgb than either CO2 or O2. I think the correct term for CO2 bound to heme is carbaminohemoglobin.
You are correct in all of this. CarbonMONOXIDE or CO (as in a poisining f.i.) has 240 times the affinity for Hb and binds the same sites as 02, but yields something called "CarboxyHb". CarbaminoHb is where CO2, or Carbondioxide, binds physiologically to Hb. Still find these talks very useful, but you gotta know a little already!
I am hoping you would clarify and correct something in your video. You show the CO2 diffusing into the blood.however, as I understand it the partial pressure of carbon dioxide is higher in the capillary bed and therefore should diffuse into the lungs to be expelled.
Great video! Mucho gracias.
Thank you for the feedback! Glad you found it helpful!
Yes, thank you. The way I understand it- the partial pressure will be higher where the concentration of gas is higher, and it will be lower where the concentration is lower. So either way, the driving force for oxygen to move across the membrane can be referred to as the partial pressure difference or the concentration difference... Correct?
The diffusion coefficient (Krogh) of CO2 is 20 times that of water across this membrane. Solubility of CO2 in water is 24 times higher than oxygen, but the molecule of CO2 is a little larger than O2 so the diffusion factor works out to 20 times that, not 5.
Thanks for watching Ronny and appreciate the comment.
Great job!
Thank you for the feedback! Glad you found it helpful!
according to Guyton the pco2 of atmospheric air is 0.3mmhg (0.04%) not 3mmhg. then total will be 760mmhg.....?
Once again, another great video! I'm very grateful to you for putting these up here! One question- it seems as though the terms "concentration gradient" and "partial pressure" are being used interchangeably throughout the video... is this correct? O2 moves down its concentration gradient; or O2 moves to where the partial pressure is lower...? To phrase my question another way: is the driving force for O2 the difference in pressure across the membrane or the difference in concentration?
I am hoping you would clarify and correct something in your video.
You show the CO2 diffusing into the blood.however, as I understand it the partial pressure of carbon dioxide is higher in the capillary bed and therefore should diffuse into the lungs to be expelled.
Yes, that should have been drawn the other way around. Obviously the CO2 from metabolism is breathed out, so the bicarbonate is high in the venous blood, and leaves the cell as CO2 and crosses the wall into the alveoles to be breathed out..
Thanks for the question Nathan. We've passed it along to the Health Ed Solutions medical review board.
Appreciate the input!
You imply that both CO2 and O2 coexist on Hgb molecules. In fact, they compete for sites on hemoglobin. Also, carboxyhemoglobin is a heme molecule carrying CO, not CO2. CO has a much higher affinity for Hgb than either CO2 or O2. I think the correct term for CO2 bound to heme is carbaminohemoglobin.
You are correct in all of this. CarbonMONOXIDE or CO (as in a poisining f.i.) has 240 times the affinity for Hb and binds the same sites as 02, but yields something called "CarboxyHb". CarbaminoHb is where CO2, or Carbondioxide, binds physiologically to Hb. Still find these talks very useful, but you gotta know a little already!
hello
Thank you for the feedback! Glad you found it helpful!
I am hoping you would clarify and correct something in your video.
You show the CO2 diffusing into the blood.however, as I understand it the partial pressure of carbon dioxide is higher in the capillary bed and therefore should diffuse into the lungs to be expelled.
Thanks for your feedback. We will ask Dr. Wolf and see what he says!