a-VO2 Difference Flashcards
Fick equation
expresses the relationship between cardiac output, oxygen consumption during 1 minute (VO2), and average difference between the oxygen content of arterial and mixed venous blood (a-VO2) difference
cardiac output = VO2/a-VO2 difference
cardiac output and oxygen utilization during rest
arterial blood carries 200 mL oxygen per L blood
1000 mL oxygen per 5 L blood
nearly 75% of blood’s original oxygen load is unused at rest and remains bound to hemoglobin
leaves 750 mL of oxygen per 5 L of blood (15 mL O2 per 100 mL blood) to return unused to the heart
extra circulating oxygen bound to hemoglobin is a reserve
cardiac output and oxygen utilization during strenuous exercise
hemoglobin saturated with oxygen in arterial blood remains nearly complete during exercise by:
greater use of already existing large quantity of oxygen carried by the blood
explained by a-VO2 difference
increased total quantity of blood pumped by the heart
explained by cardiac output
oxygen consumption & a-VO2 difference
oxygen consumption increases during exercise by a greater use of already existing large quantity of oxygen carried by the blood
factors affecting a-VO2 difference during exercise
redistribution of blood flow
skeletal muscle microcirculation
capillary-to-fiber ratio
myoglobin concentration
size and number of skeletal muscle mitochondria
skeletal muscle aerobic enzyme activity
a-VO2 difference and training
endurance training increases the quantity of oxygen extracted from circulating blood
more effective cardiac output distribution to active muscle
enhanced capacity of trained muscle fibers to extract and utilize available oxygen
increase in skeletal muscle microcirculation
increase capillary-to-fiber ratio
increased myoglobin
increased size and number of skeletal muscle mitochondria
increased skeletal muscle aerobic enzyme activity
oxygen supply (blood flow), not oxygen use (extraction) limits the maximal respiratory rate of muscle tissue
