Blood Gas Transport Flashcards
In the pulmonary capillary, the blood PO2 rises close to that in the alveolar air by the time the blood has moved _____ the distance through the capillary.
1/3
What factors allow the diffusion capacity of oxygen to increase during exercise?
Increased surface area of capillaries participating in diffusion.
Ideal Va/Q ratio in the upper parts of the lungs
What factors determine tissue PO2?
Rate of oxygen transport to the tissues
Rate of oxygen consumption by the tissues
Describe the effects of blood flow and metabolic rate on peripheral tissue PCO2.
As blood flow increases, interstitial fluid PCO2 decreases.
As metabolism increases, interstitial fluid PCO2 increases.
What is the oxygen saturation in venous blood and arterial blood?
Venous blood = 75%
Arterial Blood = 97%
How much oxygen is bound to heme groups in venous blood?
Oxygen is bound to approximately 3/4 (75%) of heme groups in blood.
How much oxygen is bound to heme groups in arterial blood?
Almost all of it (97%)
How is the oxygen utilization coefficient calculated?
It is the percentage of blood that gives up its oxygen.
5/19.4 ml O2 = 25% at rest
Strenous exercise = 75 to 85%
How can hemoglobin be viewed as a tissue oxygen buffer system?
Tissue PO2 does not rise above 40 mm Hg, and PO2 must fall to about 40 mm Hg to release 5 mL of blood.
When PO2 is high (pulmonary capillaries), oxygen binds with hemoglobin.
When PO2 is low (tissue capillaries), oxygen is released from hemoglobin.
Relate PO2 and oxygen saturation to the oxygen-hemoglobin dissociation curve.
As pressure oxygen in blood increases, hemoglobin saturation increases.
At 95 mm Hg, oxygenated blood leaves the lungs.
At 40 mm Hg, reduced blood returns from tissues.
Relate PO2 to quantity of bound oxygen per unit of blood.
As PO2 increases, there is a higher amount of of bound oxygen per unit of blood.
Relate pH to oxygen-hemoglobin dissociation curve
Decreased pH shifts the curve to the right.
This enchnces release of oxygen from the blood in the tissues and enhances oxygenation of blood in the lungs.
Increased pH shifts the curve to the left. This occurs in the lungs.
What is the Bohr effect, and what effect does it have on the oxygen-dissociation curve?
It shows the effect of pH on oxygen-hemoglobin curve. As pH decreases, the curve shifts to the right. As pH increases, the curve shifts to the right.
What occurs when blood pH decreases?
The oxygen-hemoglobin curve shifts to the right
Oxygen is released more readily from blood in the tissues.
Oxygenation of blood in the lungs occurs.
What occurs as pH increases?
The oxygen-hemoglobin curve shifts to the left.
This occurs in the lungs.
What effect does ADP have on oxygen usage?
As ADP increases, the rate of oxygen usage increases.
When cellular pH is more than ____, ADP becomes the limiting factor in the rates of chemical reactions.
1 mm Hg
What are the three ways carbon dioxide is transported in the blood?
Dissolved in the blood (7%)
Transported as carbonic acid (70%)
Transported as carbamino hemoglobin
In order to transport carbon dioxide into the blood as carbonic acid, what enzyme is needed?
carbonic anhydrase.
A bicarbonate/chloride transporter is also needed.
What is the Bohr effect?
An increase in blood carbon dioxide causes oxygen to be displaced from hemoglobin.
This shifts the oxygen hemoglobin dissociation curve to the right (decreased pH).
What is the Haldane effect?
Binding of oxygen with hemoglobin displaces carbon dioxide from blood.
The binding of oxygen to hemoglobin causes hemoglobin to become a _____
stronger acid.
The more acidic hemoglobin is (due to oxygen binding), the ____ of a tendency it has to bind with carbon dioxide.
less
Increased ____ of hemoglobin causes it to release hydrogne ions.
acidity
Why may blood be red in carbon monoxide poisoning?
THe oxygen content of blood is greatly reduced, but PO2 of the blood may be normal.
Describe the pressure differences that cause oxygen to diffuse into the pulmonary capillary.
104 mm Hg (PO2 in alveolus) - 40 (PCO2 in venous blood) = 64 mm Hg.
