exam 3 part 2 Flashcards
contraction
systole
atrial systole
SL close, AV open
-blood to ventricles
ventricular systole
-blood to pulm. trunk and a.a.
phases of ventricular systole
-isovolumetric contraction (all valves are closed)
-ventricular ejection (SL open AV close)
when do chambers fill with blood
diastole
early ventricular diastole
isovolumetric relaxation (all valves are closed)
late ventricular diastole
atria and ventri8cles fill passively
-av open SL closed
what affects output?
preload and afterload
what determines prelaod
-stretching when ventricle diastole, venous return, blood in ventricle post systole
what is aferload?
pressure the heart has to generate to pump blood out of heart, main source of afterload is the systemic arterial pressure
what does hr control
the frequency at which blood is ejected from the heart
what affects hr
-medulla ob, sympathetic and parasypathetic activation at the vardiovascular vasomotor control center, neural reflexes (low bp increases hr bc the arterioles constrict), hormones (epi, ne, thyroid)
friction btwn blood and vessel wall is?
vascular resistance
decrease vessel radius
increase friction and resistance
what regulates CO in the body
cardia centers (parasym and sympathetic nervous systems) and the vasomotor center that regulates vessel diameter `
what responds to bp changes
baroreceptor reflexes