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primary functions of the cardiovascular system during aerobic exercise?
to deliver oxygen and other nutrients to the working muscles and remove metabolites and waste products
cardiac output
the amount of blood pumped by the heart in liters per minute and is determined the quanitity of blood ejected with each beat (stroke volume) and the heart's rate of pumping (heart rate); Q=stroke volume x heart rate
stroke volume
quantity of blood ejected with each beat; measured in milliliters of blood per beat; begins to increase at the onset of exercise and continues to rise until the individual's oxygen consumption is at approximately 40%-50% of maximal oxygen uptake, at this point SV begins to plateau
heart rate
heart's rate of pumping; measured in beats (contractions) per minute
end-diastolic volume
the volume of blood available to be pumped by the left ventricle at the end of the filling phase or diastole
two physiological mechanisms responsible for the regulation of stroke volume
2. the action of the catecholamines including epinephrine and norephinephrine, which are hormones of the sympathetic nervous system that produce a more forceful ventricular contraction and greater systolic emptying of the heart
venous return
the amount of blood returning to the heart; increased during aerobic exercise due to a combination of venoconstriction (induced via increased sympathetic nervous system activation), the skeletal pump, and the respiratory pump (increased respiratory frequency and tidal volume)
frank-starling mechanism
with an increased end-diastolic volume, the myocardial fibers become more stretched than at rest, resulting in more forceful contraction and an increase in force of systolic ejection and greater cardiac emptying; the concept that the force of contraction is a function of the length of the fibers of the muscle wall
ejection fraction
a measurement of the percentage of blood that leaves the heart everytime it contracts
oxygen uptake
the amount of oxygen consumed by the body's tissues
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