control of cardiac output Flashcards
How is cardiac output (CO) calculated?
Heart rate (BPM) x stroke volume (L)
what is stroke volume?
volume of blood ejected by each ventricle per beat
what’s the units of CO?
L/min
do athletes have higher or lower resting CO?
higher
do athletes have higher or lower resting CO?
higher
why do athletes have higher COs?
reduced heart rate and increased stroke volume
do athletes have a heavier or lighter heart mass?
heavier
what factors affect Heart Rate (HR)?
autonomic innervation
hormones
how is stroke volume calculated?
End diastolic volume (EDV) - end systolic volume (ESV)
what’s EDV/ end diastolic volume?
volume of blood in a ventricle at the end of loading or filling (after atria emptying)
what’s ESV/ end systolic volume?
volume of blood that remains in the heart after systole
define contractility
contractile ability of cardiac muscle at given preload
increasing contractility affects stroke volume how?
increases it
what’s a positive intropic affect?
when a molecule increases the contractility of the heart
what exerts a positive intropic effect on heart?
SNS and adrenaline
as well as having a positive intropic effect on the heart, how else does the SNS affect the heart?
increases conduction of cardiac impulse
what type of intropic influence does the PNS have on the heart?
negative
where does the PNS have a negative intropic influence on the heart?
the vagal nerves only innervate the atria, not the ventricles
what is a chronotropic effect?
something that effects heart rate
what affects afterload?
vasoconstriction and dilation
what’s afterload?
the pressure against the heart must work to eject blood during systole
what is blood pressure?
the pressure placed on the walls of vessels by blood
what is hypotension?
blood pressure too low
what is hypertension?
blood pressure too high
