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31 Cards in this Set

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  • Back
How does oxygen move in the blood
O2 travels down a partial pressure gradient at each interface when moving from lungs to tissue
What two compartments in the blood hold O2
1. dissolved in plasma
2. bound to hemoglobin
How should one think of Hemoglobin in regards to O2
As a buffer, in equilibrium with dissolved O2
Is O2 soluble in water
No, it is poorly soluble in water
How is the avidity in which O2 binds to Hb influenced
the way O2 binds to Hb is strongly influenced by the tertiary structure of the Hb molecule
If all hemoglobin sites are saturated what is the vol % of O2 in the blood
20 vol% per 100ml OR
2 vol% per 10ml
what does 1 vol% coorelate to
1 ml O2 contained in 100 ml of blood
How is most O2 found in the blood
Very little O2 is dissolved in plasma, the vast majority is carried bound to hemoglobin
How does O2 move in and out of compartments
Through the dissolved form, ex: when O2 is delivered to a tissue, it is the dissolved gas that moves out.
What happens when O2 is delivered to a compartment
The dissolved gas moves out, this lowers PO2 in plasma and causes Hb to release O2--b/c Hb is a buffer.
How do gases dissolve and move
Gases move down partial pressure gradients. O2 dissociates from Hb and goes into solution in plasma, the dissolved gas then diffuses down a partial pressure gradient into interstitial space
How does O2 move in alveolar spaces
PO2 in alveolus is held at 100 by respiratory pumping. O2 diffuses down partial pressure gradient into plasma, raising PO2 in plasma. O2 associates with Hb for transport. (PO2 alveoli=40)
what determines the concentration of O2
determined by PO2 (partial pressure of O2), which determines the number of O2 molecules that are dissolved in the plasma
Is CO2 transported in the blood the same way as O2
No, transported differently. CO2 is transported in 3 ways:
dissolved in plasma (H2CO3)
as bicarbonate (HCO3)
bound to Hb (HbCO2)
What is a carbamino
What is the solubility of O2 in water
.003 vol%
what is the solubility of CO2 in water
.06 vol%
what is the PCO2
40 torr
What does it mean in the physiological sense that CO2 is 20X's more soluble in blood than O2
20 X's more CO2 is carried in the dissolved form than O2
What catalyzes the reaction of CO2 and H2O in the RBC
carbonic anhydrase
what buffers the H+
how does the bicarbonate ion leave the RBC
it diffuses down its concentration gradient out of the RBC. It is replaced by an inward flux of Cl- ions.
About how much CO2 is transported as bicarbonate
Why does the enzymatic reaction of CO2 and water take place in systemic capillaries
b/c Hb is deoxygenated and therefore available to buffer H+ ions
How does the enzymatic exchange of CO2 occur in the lungs
in the lungs, the process is repeated in reverse. Hb gains O2, which displaces H+. This drives the reaction of H+ and HCO3- back to the H2O & CO2 direction. The CO2 leaves the RBC's and capillaries by diffusion
How can CO2 enter RBC readily
it is lipid soluble
where is carbonic anhydrase found and where are H+ ions generated
inside the RBC (both).
H+ ions being generated in the RBC is a good place because it is buffered by Hb which is also found in the RBC...buffering by Hb minimizes the resulting change in H+ion concentration
How are carbaminos formed and does Hb have a high affinity for CO2
CO2 reacts with deoxygenated Hb to form carbamino compounds. It is a fast reaction. Hb has a low affinity for CO2
How much CO2 is transported as carbamino compounds
What is the relationship between PCO2 and CO2 content of blood
it is a linear curve and does not show any saturation
What are some things that effect Hb's affinity for O2
H+ ion concentration-increasing H+ ions concentration lowers Hb affinity for O2

Temp-increasing temp lowers affinity for O2

PCO2-at high PCO2, HBCO2 is higher thus reducing # of Hb sites available for O2 binding

certain diseases- carbon monoxide poisoning. CO binding to Hb dramatically increases teh affinity of Hb for O2