+
Related Flashcards
Related Topics
Cards In This Set
| Front | Back |
|
What is the reduction of PO2 from the alveolus to the aorta called?
|
A-a gradient
(remember: "a" stands for a systemic artery, not the pulmonary artery) |
|
What is the trend for PO2 from alveolus --> cell?
|
It decreasesPO2 alveolus > aorta > interstitium > intracellular
|
|
What is the reason for the reduction of PO2 from the artery to the cell?
|
Consumption of O2
|
|
Describe what happens to the partial pressure of O2 from the alveolus to the cells of the tissues.
|
The consumption of O2 makes the intracellular PO2 lower than the PO2 in the interstitium. The ongoing loss of O2 from the interstitium makes the PO2 lower in the interstitium than in the capillary. O2 will diffuse out of the capillary until the concentration of O2 in the capillary = concentration of O2 in the interstitium.
|
|
What are the PO2s in the cell, interstitium, and capillary?
|
PO2 in the cell = 23 mmHg (on average)PO2 in the interstitium = 40 mmHg PO2 on arteriolar end of capillary starts at about 100 mmHg, but as it moves through the capillary and diffuses out into the interstitium, it approaches equilibrium with the interstitium, so at the venular end it is also 40 mmHg
|
|
Bulk oxygen transport is done by dissolved O2/Hemoglobin
|
Hemoglobin
|
|
What is the driving force for oxygen movement into the cell?
|
PO2 (dissolved O2)(important to keep this in mind even though the bulk of transport is by Hb, PO2 moves the O2 into the cell)As the PO2 falls in the capillary during diffusion, O2 will dissociate from the Hb and keep the PO2 from dropping too rapidly (i.e. keep the gradient large so O2 can still diffuse)
|
|
Describe the effects of blood flow on interstitial PO2
|
Increased blood flow --> increased interstitial PO2Decreased blood flow --> decreased interstitial PO2
|
|
At any blood flow, an increase in cellular O2 consumption will increase/decrease interstitial PO2
|
Decrease
|
|
T/F. A decrease in interstitial PO2 will either increase or decrease the cellular PO2 depending on the cause of the decrease.
|
FALSE. It will decrease the cellular PO2, no matter what the cause.
|
|
Cellular enzymes continue to function normally at PO2 as low as ______
|
1-3 mmHg
|
|
What happens if PO2 < 1-3 mmHg?
|
Switch to anaerobic metabolism, and get production of lactic acid. This can happen if there is an increase in oxygen consumption without adequate supply (i.e. heavy exercise), or if there isn't sufficient circulatory flow.
|
|
T/F. Under usual conditions, the amount of O2 transferred in the dissolved state is far greater the the amount of O2 transferred by Hb.
|
FALSE. Amt of O2 transported by Hb >>> amt of O2 transported in dissolved state
|
|
What is the percentage of RBCs in the blood? What is this called?
|
45%Hematocrit
|
|
Which are more numerous in the blood- RBCs or WBCs?
|
RBCs outnumber WBCs 1000:1
|
