Flashcards in Exercise physiology Deck (13)
what is the effect of SNS on BP?
vasoconstriction - alpha adrenergic
increase HR - beta adrenergic
increase contractility - beta adrenergic (myocardium)
EPI release from adrenal medulla
what is responsible for an increased BP set point?
greater motor output going to muscle compared to central command, resulting in increased sympathetic nerve activity
what two processes are responsible for regulating BP?
exercise pressor reflex (feed back)
central command baroreceptor set point (feed forward)
what is the role of the exercise pressor reflex?
corrects mismatch between muscle BF and muscle metabolism during exercise
if SNA increase during exercise, how does blood flow increase to muscle?
functional sympatholysis - metabolic autoregulation overtakes the sympathetic nervous system in controlling blood flow to muscle
increased accumulation of VD metabolites as metabolism increases during exercise - muscle vasodilation
increased sympathetic nerve activity to muscle - muscle vasoconstriction
Explain why upper body exercise (snow shoveling, arm wrestling) increases blood pressure much more than a using large muscle groups during dynamic exercise (running, cycling, swimming).
greater HR response
greater pulmonary ventilation
higher perceived exertion
augmented pressor response
redistribution of flow to arms (from legs)
Define the determinants of maximal oxygen consumption (VO2max)
VO2 = HR x SV x avO2diff
Explain how heart rate can increase at the beginning of exercise, even when a high dose of beta blockers are administered.
NE binding to beta adrenergic receptors on the SA node
baroreflex resetting to establish new set point
why does SV increase during exercise?
increased venous return
increased SNA on cardiac muscle
what happens to arterial and venous oxygen content as vO2 increases?
arterial oxygen content rises slightly
venous oxygen content decreases
why does avO2diff increase during exercise?
1. redistribution of flow to active tissues during exercise
2. rightward shift of the oxyHb dissociation curve
is the core temperature set point changed during exercise?