week 13 Flashcards
factors that influence EDV/preload
venous return
skeletal muscle pump
filling time
venous tone
venous BP
blood volume
factors that influence afterload
arterial BP
vasodilation/constriction
vascular resistance
factors that influence contraction force
preload
contractility
during extended heavy exercise, cardiac output remains stable but…
HR increases and SV decreases
how does decreased blood volume lead to decreased stroke volume?
- decreased blood volume leads to decreased venous return
- decreased prelaod/decreased EDV
- decreased SV beause less blood in the heart before contraction
- decreased contraction force
- lower SV bc less of the blood that is in the ventricle gets squeezed out
- decreased prelaod/decreased EDV
- decreased blood volume leads to lower mean arterial pressure
- lower afterload
- increased SV bc the heart needs to overcome less force to eject blood
- lower afterload
overall: the effect of lower venous return outweighs the effect of lower MAP and SV drops
if lower blood volume leads to decreased SV, what would happen to HR?
HR increases in order to keep Q constant
copy down second slide on page 5 of CVII
review first slide on page 6 of CVII
how do we mitigate cardiovascular drift and its functional consequences?
stay hydrated and cool
write down page 7 of CVII
what happens in acute exercise?
- numerous changes (increased mvmt, emotions, body temp, local metabolites, etc…) are detected by receptors throughout the body and are communicated to the cardiovascular control center in the medulla
- the cardiovascular control center integrates the inputs and responds by reducing in PSNS outflow to the SA node via the vagus nerve. if needed, SNS outflow to the SA node via the accelerator nerve will also be increased
- the result is an increase in HR up to HRmax at max SNS stimulation
what are some cardiovascular challenges of exercise?
- we need to pump a lot more blood per minute
- we need to direct blood flow to the right places
copy down second slide on page 9 of CVII
will MAP always be closer to or further from DBP than SBP
MAP will always be closer to DBP than to SBP
diastolic vs systolic BP
diastolic BP: intra-arterial pressure during ventricular relaxation
systolic BP: intra-arterial pressure during ventricular contraction
what do SBP and HR influence?
SBP (force of contractions) and HR (how many contractions) influence myocardial work and myocardial VO2
what is the formula for rate pressure product (RPP)
RPP provides an estimate of myocardial work aka “strain on heart”
rate pressure product (RPP) = SBP x HR / 100
how do we selectively vasodilate/vasoconstrict different vessels?
smooth muscle in arterioles is regulated via:
- autonomic nervous system control (dilation/constriction in response to SNS/PSNS innervation)
- hormonal control (constriction in response to epinephrine/norepinephrine)
- intrinsic metabolic control (dilation/constriction in response to local metabolic activity)
copy down page 12 of CVII
how do patterns of blood flow distribution change during exercise?
- increased O2 delivery to skeletal muscle, heart and brain
- decreased O2 delivery to viscera
- increased blood flow to skin at lower intensities (to help thermoregulate) but skeletal muscle takes priority at max exercise so blood flow to skin decreases
review page 14 of CVII
acute vs. chronic responses to exercise
acute responses: how the body responds to a single bout of exercise
chronic: how the body changes in response to chronic (repeated) exposure to exercise - training adaptations
what are the 5 training principles
- overload
- progression
- individual differences
- reversibility
- specificity
aerobic exercise imposes a high ___ on the heart and resistance exercise imposes a high ___ on the heart
volume load
pressure load
why do endurance athletes have bradycardia (low HR) at rest?
- cardiac adaptations + increased blood volume = increased SV
- can achieve the same Q with lower HR
