Exercise physiology

Question 1

what is the effect of SNS on BP?

Answer 1

vasoconstriction - alpha adrenergic
increase HR - beta adrenergic
increase contractility - beta adrenergic (myocardium)
EPI release from adrenal medulla

Question 2

what is responsible for an increased BP set point?

Answer 2

greater motor output going to muscle compared to central command, resulting in increased sympathetic nerve activity

Question 3

what two processes are responsible for regulating BP?

Answer 3

exercise pressor reflex (feed back)

central command baroreceptor set point (feed forward)

Question 4

what is the role of the exercise pressor reflex?

Answer 4

corrects mismatch between muscle BF and muscle metabolism during exercise

Question 5

if SNA increase during exercise, how does blood flow increase to muscle?

Answer 5

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

Question 6

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).

Answer 6

greater HR response 
greater pulmonary ventilation 
higher perceived exertion 
augmented pressor response 
redistribution of flow to arms (from legs)

Question 7

Define the determinants of maximal oxygen consumption (VO2max)

Answer 7

VO2 = HR x SV x avO2diff

Question 8

Explain how heart rate can increase at the beginning of exercise, even when a high dose of beta blockers are administered.

Answer 8

NE binding to beta adrenergic receptors on the SA node

baroreflex resetting to establish new set point

Question 9

why does SV increase during exercise?

Answer 9

increased venous return
increased SNA on cardiac muscle
decreased TPR

Question 10

what happens to arterial and venous oxygen content as vO2 increases?

Answer 10

arterial oxygen content rises slightly

venous oxygen content decreases

Question 11

why does avO2diff increase during exercise?

Answer 11

1. redistribution of flow to active tissues during exercise

2. rightward shift of the oxyHb dissociation curve

Question 12

is the core temperature set point changed during exercise?

Answer 12

no

Question 13

what is the compensatory thermoregulation response during exercise?

Answer 13

1. evaporative heat loss - primary method of heat removal

2. cutaneous vasodilation (dependent sympathetic cholinergic activation)