Integration of Cardiac Function Flashcards
what receptors are used for sympathetic and parasympathetic effects upon the heart and what are their second messengers?
SNS- beta1 adrenergic receptors (increase cAMP)
PNS- M 2 muscarinic receptors (decrease cAMP)
what are the two intrinsic mechanisms or regulating cardiac output?
starlings law- increased volume=increased contractility
membrane potentials and therefore ionic concentrations
what are the extrinsic mechanisms of regulation of cardiac output?
neuronal and hormonal signaling
why is the cardiac output the same into the aorta and into the pulmonary artery?
because the two circuits are in series
graphically what is the difference between cardiac output and oxygen consumption?
linear
what eight factors increase cardiac output?
fever, exercise, anxiety, body weight, pregnancy, hyperthyroidism, chronic anemia and hypoxia
what five factors decrease cardiac output?
sleep, aging, severe anoxia, acute hemorrhage and heart disease
what is histotoxic hypoxia?
tissue poisoning that causes the tissues to be less able to use oxygen
why does cardiac output have varying responses to hypoxia and severe anoxia?
because severe anoxial causes oxygen deprivation in the heart and decreases cardiac output
what is the effect of hypertension on cardiac output?
it is unaltered
what are the only two ways to produce a different steady state match of CO?
changing the cardiac function curve or the vascular function curve
during exercise what happens to the body’s vasculature and what is the overall effect?
there is arteriolar and venous vasoconstriction. the overall effect is functionally increasing venous return by the venous constriction
how does muscle contraction promote venous return?
by pumping venous blood past valves towards the heart
why is there an overall decrease in peripheral resistance to blood flow during exercise?
because local hypoxia, hypercapnea and acidemia promote vasodilation and prevent MAP from increasing too much
what happens to the mean systemic filling pressure during an increase and a decrease in sympathetic stimulation?
increase- increase in MSFP and decrease with a decrease in sympathetic stimulation
what happens to cardiac output and venous return during exercise? does a difference in central venous pressure cause this?
both increase, however here is not an increase in CVP