O2 content of blood

[ctizzle13498]

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Ok so in the respiratory section of first aid, i was a little confused:

It says O2 content= (O2 binding capacity * % saturation) + dissolved O2.

Then it says: O2 content of arterial blood decreases as Hb falls, but O2 saturation and arterial PO2 do not.

I don't really get this. Where is the arterial P02 in the first equation?

 

[ctizzle13498]

Also, on the section of Response to exercise: I don't get why there is no change in Pa02 and PaC02.

Thanks again!

 

[Phlame217]

Ok so in the respiratory section of first aid, i was a little confused:

It says O2 content= (O2 binding capacity * % saturation) + dissolved O2.

Then it says: O2 content of arterial blood decreases as Hb falls, but O2 saturation and arterial PO2 do not.

I don't really get this. Where is the arterial P02 in the first equation?

Alrighty...

Hb as 4 binding sites for oxygen. %sat is the percent of those 4 binding sites that are bound to oxygen. So, if 4/4 are bound, you get 100% Saturation. If 3/4 are bound 75%, etc.

Therefore if you reduce the amount (quantity) of Hb in the blood, you reduce the bloods oxygen carrying capacity (less workers to carry oxygen) BUT %saturation stays HIGH because the workers still there are carrying their typical load of oxygen. (So as you reduce O2 binding capacity)

Now as far as Arterial PO2, its partial pressure is between 100mmHg and 60mmHg. This does NOT change in anemia. The partial pressures remain the same, however, you do reduce the VOLUME of oxygen being delivered due to less workers.

 

[turkeyjerky]

Also, on the section of Response to exercise: I don't get why there is no change in Pa02 and PaC02.

Thanks again!

People are able to increase their respiration several fold during exercise, which will keep the PaCO2 and PaO2 steady.

 

[jfgavina]

that's not enough, cardiac output must increase in order to deliever proper oxygen to tissues and remove oxygenate blood at lung.

 

[naseeha]

Ok so in the respiratory section of first aid, i was a little confused:

It says O2 content= (O2 binding capacity * % saturation) + dissolved O2.

Then it says: O2 content of arterial blood decreases as Hb falls, but O2 saturation and arterial PO2 do not.

I don't really get this. Where is the arterial P02 in the first equation?

I believe the arterial PO2 in the first equation is the dissolved O2.

 

[ctizzle13498]

I believe the arterial PO2 in the first equation is the dissolved O2.

that makes A LOT of sense....so that means basically that out of the 3 things....only 1 thing is changed....i get it now! Thanks guys!!!

 

[lord_jeebus]

that makes A LOT of sense....so that means basically that out of the 3 things....only 1 thing is changed....i get it now! Thanks guys!!!

Don't forget that there is a relationship between PO2 and saturation, ie. the oxyhemoglobin dissociation curve.