Cardiac Events: Cardiac Output

stroke volume * heart rate

how do we calculate cardiac output?

contractibility and end diastolic volume

what factors affect stroke volume?

increase ICF Ca2+ availability and venous return

how can contractibility be increased?

constricting vein via sympathetic system, skeletal muscle pump, respiratory pump

how can venous return be increased?

both parasympathetic and sympathetic

what system(s) are involved in affecting heart rate?

ACh

what is the efferent for parasympathetic involvement in heart rate?

muscarinic receptors

what is the effector for parasympathetic involvement in heart rate?

decreases Ca2+ influx, increases K+ output, hyperpolarizing the cell and decreasing heart rate

what is the response for parasympathetic involvement in heart rate?

norepinephrine

what is the efferent for sympathetic involvement in heart rate?

beta 1 receptors

what is the effector for sympathetic involvement in heart rate?

increase in influx of Na+ and Ca2+, depolarizing the cell and increasing heart rate

what is the response for sympathetic involvement in heart rate?

sympathetic

what system(s) are involved in contractibility?

adrenal medulla

what is the control center for sympathetic involvement in contractibility?

epi and norepi

what is the efferent for sympathetic involvement in contractibility?

beta 1 receptors that activate cAMP

what is the target cell for sympathetic involvement in contractibility?

voltage gated Ca2+ channels and phospholambam

what is phosphorylated for contraction?

more calcium comes into ICF, more calcium is pumped into the SR, releasing more calcium to create a STRONGER contraction

explain phosphorylation of 1st calcium

more calcium is pumped and more calcium can be stored and removed, shortening binding time and create SHORTER CONTRACTIONS

explain phosphorylation of phospholambam

phospholambam

protein on SR that directly works on calcium pump (2nd calcium) from the cytosol

preload

blood volume entering ventricles (end diastolic volume) at the end of diastole (just before contraction)

afterload

resistance or pressure from aorta that ventricles must overcome in order to circulate blood during systole (ejection phase)

preload, contractibility, afterload

what factors affect stroke volume?