Cardiac Output

Cardiac output (CO) =

stroke volume x cardiac rate

Stroke Volume

the volume of blood pumped by each ventricle per beat

what is stroke volume related to

the strength of ventricular contraction

cardiac rate

frequency of heartbeats within one minute

ways to regulate CO

cardiac rate via beats per min, stroke volume via strength of ventricular contraction

what sets the cardiac rate

the SA node

what happens if SA node activity increases

more pacemaker potentials, increased heart rate

the sympathetic and parasympathetic have ______ effects on the heart

anagonistic

the sympathetic affects __________ by

the atria and ventricles by modifying both pace and contraction strength

results of sympathetic

increased cardiac rate and stroke volume

the parasympathetic affects the pace of the

atria

the parasympathetic results in

decreased cardiac rate

what happens to ventricular contraction with the parasympathetic

stays the same

what does the parasympathetic system alter

SA and AV nodes in the atria

parasympathetic does what to the Sa node firing rate and AV node excitability

decreases

parasympathetic does what to the delay time between SA and AV

increases delay time

how does the parasympathetic weaken atrial contraction

by shortening the plateau phase during action potentials so the contractile cells hyperpolarize faster

what all does the sympathetic system affect

atria, ventricles, SA, AV

the sympathetic increases SA node firing rate, which does what

makes more pacemaker potentials

the sympathetic reduces AV node delay, which does what

shorter time between atrial/ventricular contractions and shorter conduction time throughout the heart

sympathetic increases/decreases contraction strength for both the atria and ventricle

increases

what is the main molecule that the sympathetic system increases in order to increase heart rate

cAMP

overview of what caffeine does

binds to adenine receptors, preventing adenine from binding, which blocks adenine from causing drowsiness

what molecule does caffeine inhibit

phosphodiesterase (PDE)

what senses does caffeine enhance

vision and smell

regulating stroke volume is dependent on the manipulation of

muscle tension

what is the intrinsic controller of stroke volume

venous return

what is the extrinsic controller of stroke volume

sympathetic involvement

what makes cardiac muscle different from skeletal muscle

cardiac muscle does not rest at an optimal length

does cardiac muscle follow the length-tension relationship

yes

EDV is based upon….

the amount of venous return

amount of blood pumped is related to

muscle fiber length

greater EDV means

greater amount of stretch

optimal range results in

maximum contraction stength

pathway of intrinsic control of stroke volume

more venous return → more stretching → longer fibers → optimal length → greater contraction force

Frank-Starling Law of the Heart

in systole, the heart ejects the volume of blood received during diastole (venous return matches stroke volume)

how do you enhance contractions at a given end diastolic volume

trigger more Ca release to allow more Cross Bridge Cycles which produces stronger contractions therefore increasing stroke volume