CV PHYSIO Flashcards
what are the phases of the cardiac cycle?
phase 1: atrial contraction phase 2: isovolumetric contraction phase 3: rapid ejection phase 4: reduced ejection phase 5: isovolumetric relaxation phase 6: rapid filling phase 7: reduced filling
T/F, atrial contraction is responsible for total filling of the ventricles?
F, nope
what percent of blood flows through the atria before the atria contract?
80%
in certain conditions, like tachycardia, atrial contraction can contribute up to 40% of ventricular filing, this is called?
atrial kick
pacemaker cells have the property of?
automaticity
depolarization spreads to?
contractile myocytes
dominant pacemaker of the heart? located where? what are the intervals?
SA node, upper posterior wall of RA, 60-100 bpm
how does the impulse spread?
from the SA node throughout atria, through Bachman’s bundle to the LA, then through internodal pathways to the AV node
what is the effect of the cardiac muscle staying contracted longer than skeletal muscle?
when the refractory period is longer?
enhances ejection of blood
ensures muscle relaxation before next contraction
BP equals?
CO x SVR
CO equals?
SV x HR
stroke volume affected by?
ventricular preload
ventricular afterload
cardiac muscle contractility
resistance of the arteriolar vessels?
depends on the radius of the vessels
arterioles have basal tone (intrinsic tone)
they remain in a state of partial construction even when all external influences on them are removed
changes are affected by local, neural and hormonal mechanisms
autoregulation
local regulation of vascular tone?
hypoxia
hypercapnia
acidosis
opening of precapillary sphincter
mediators: NO, prostaglandins, histamine, bradykinin
afferent sensory information from the arterial baroreceptors enter the? then relayed where?
medullary nucleus tractus solitarius
medulla and hypothalamus
efferent information leaves medulla from?
rostral ventrolateral medulla
cell bodies of the preganglionic fibers are located where?
where do axons synapse on?
T1-T2 and exit the spinal cord in the ventral roots
paravertebral ganglia of sympathetic chain
prevertebral ganglia
chromaffin cells of the adrenal medulla
major effects of norepinephrine on the B1 receptors in the heart?
positive chronotropic effect
positive inotropic effect
positive dromotropic effect
positive lusitropic effect
