Taylor- CV response to exercise Flashcards
Locomotion/exercise exerts a global stress on the cardiovascular system by rapidly increasing _____
metabolic demand (O2 demand to skeletal m.)
what increases up to 5 times with exercise compared to resting level
cardiac output (CO)
___% of cardiac output may go to active muscle during exercise
> 80%
what 4 things happen in response to exercise
- anticipation (fight or flight)
- vasodilation
- baroreceptor reflex
- muscle pump
Immediately before activity begins, a “fight or flight” response is initiated – very brief spike in sympathetic outflow
anticipation
what overcomes sympathetic vasoconstriction during exercise
active hyperemia
what reduces SVR in active muscle
vasodilation
during exercise, there is a large-scale skeletal m. vasodilation and drop in SVR which reduces arterial pressure, how do baroreceptors respond and why
HR and contractility increase as does vasoconstriction—>to maintain bp (MAP)
what increases allowing for modest but sustained increase in arterial pressure during exercise
the “set point”
dynamic contraction of skeletal m. that enhances blood and lymph flow
muscle pump
dynamic contraction of skeletal m. that enhances venous return to heart
muscle pump
what needs to keep up with extra blood flow to the tissues
lymph flow
additional feature of exercise that is released and causes vasodilation enhanced blood and lymph flow
histamine
neurotransmitters released from adrenal medulla during exercise
Epi and NE
Stretch and chemical receptors in active muscle signal to medulla - potentiate sympathetic drive
muscle reflexes
Initially, skin vasculature constricted by ____
sympathetic outflow
With sustained or intense activity, heat stress and high sympathetic outflow increase _____ to sweat glands
sympathetic cholinergic outflow
effects of sympathetic cholinergic outflow
sweat and vasodilation
this increases w/ exercise allowing gas exchange to meet the O2 demand
ventilation
when you cross threshold from moderate to intense exercise, what happens
- blood pH decreases do to increase in lactate
- ventilation rate increases
______ slows O2 diffusion from alveoli to arterial circulation; seriously limits O2 loading of Hb during exercise
lung disease
major effect of exercise
CO (cardiac output) goes up and stays up
what decreases when exercise begins allowing for O2 delivery to muscles
vascular resistance
overall process of sustaining high level of sympathetic outflow and maintaining bp to perfuse organs
exercise
what actually causes CO to increase:
- increase in heart contractility
- increase venous tone (vasoconctriction)
- decrease arterial tone (vasodilation)
VO2
O2 consumption
key indicator of exercise performance
VO2
VO2=
CO (arterial O2-venous O2)
cardiac output where majorly increases with exercise
skeletal muscle
Main thing that drives sympathetic outflow for entire duration of exercise
decreased systemic vascular resistance
quick source of ATP for muscle that is depleted quickly
PCr (phosphocreatine)
uses glycolysis; lactate formed; limited ATP
anaerobic exercise
uses oxidative metabolism and a lot of ATP
aerobic exercise
used for prolonged exercise or very light exercise
FA’s
effects of exercise training
SV increases
resting HR lower
maximal CO increases
hormone produced by kidneys that increases production of RBC’s
EPO (erythropoietin)
used to treat anemia in people w/ severe renal disease
EPO
used for doping in endurance athletes to increase O2 carrying capacity during exercise
EPO
what can unmask coronary artery disease
exercise
arterioles already maximally dilated, so they steal flow from other arterioles and become ischemic during exercise
vascular “steal” phenomenon
to test for heart disease
stress test
patient’s on treadmill or stationary bike and have what monitored
ECG and BP
candidates for stress test
known/suspected CAD
heart failure, etc.
stress test measures this; compares metabolic rate during activity to rest
METs
3 additional stress tests
- echocardiogram
- nuclear stress test
- drugs
pathology indicated if something abnormal is found during stress test
positive stress test
strongest predictor of mortality from stress test
very low exercise capacity (<5 METs)
