cardiac output

venous return: veins have thinner, less muscular walls than do arteries and thus

have a higher compliance; veins can hold more blood

venous return: mean venous pressure is

only 2 mm Hg

venous return

sympathetic nervous system, skeletal muscle pump, one-way venous valves, pressure difference between thoracic and abdominal cavities

edema is

excessive accumulation of tissue fluid

edema is normally prevented by

proper balance between filtration and absorption

edema can be cause by

high arterial pressure → excessive filtration; venous obstruction; leakage of plasma proteins into the interstitial space; decreased plasma proteins production (liver disease)

baroreceptors are

stretch receptors in the aortic arch & carotid sinuses

baroreceptors: increased stretch →

increase in action potentials

baroreceptors: decreased stretch →

decrease in action potentials

sensory information from baroreceptors is

integrated in the brain stem

intrinsic control: frank-starling law

the length of ventricular contraction varies directly with the end-diastolic volume

stroke volume is

regulated by three variables

stroke volume: end diastolic volume

amount of blood in the ventricles just prior to contraction

stroke volume: total peripheral resistance

a decrease in resistance makes it easier for the heart to pump blood → increases circulation

stroke volume: contractility

an increased force of contraction increases the amount of blood pumped