cardiovascular control Flashcards
what equation relates mean arterial pressure, cardiac output and total peripheral resistance
MAP=COxTPR
what is the MAP=COxTPR equation derived from?
the hemodynamic equation flow = pressure/resistance
or pressure=flow*resistance
how can cardiac output be calculated?
heart rate x stroke volume
what does diastolic pressure depend on?
the degree of dilation of constriction of the arteries
what does systolic pressure depend on?
peripheral resistance (diastolic pressure) AND cardiac output because it is the diastolic pressure plus the pressure derived from the cardiac output
how is pulse pressure calculated?
pulse pressure=systolic pressure-diastolic pressure
what is pulse pressure influenced by?
mainly cardiac output, but also elasticity of arteries and total peripheral resistance
what is minute to minute blood pressure mostly regulated by?
the autonomic nervous system
what does the sympathetic nervous system do to the cardiovascular system?
increases cardiac output, increases total peripheral resistance thus increasing blood pressure and blood flwo to skeletal muscle beds
what does the parasympathetic system do to the cardiovascular system?
decreases cardiac output, decreases total peripheral resistance, decreases blood flow to skeletal muscles; stimulates rest and digest response
what does acetylcholine bind to on the heart?
muscarinic receptors
what adrenergic receptors are present on the heart and what do they bind?
B1 receptors and they bind epinephrine and norepinephrine
what adrenergic receptors are present on most arterioles and what do they bind?
alpha1 receptors and they bind epinephrine and norepinephrine
what adrenergic receptors are present in skeletal muscle beds and what do they bind?
beta2 and they bind mostly epinephrine
what do mild stimulations of the sympathetic system cause?
release of mainly norepinephrine
what do major stimulations of the sympathetic nervous system cause?
release of norepinephrine and epinephrine
is there parasympathetic innervation to arterioles?
no
are the muscarinic receptors at the arterioles? what are the implications?
yes. even though there are receptors there is no innervation so physiological effects can be different than pharmacological effects
does the baroreceptor reflex function in conjunction or in opposition to drug injections?
the baroreceptor functions to control perturbations in blood pressure mainly by controlling heart function so if the heart is producing an opposite response than expected following drug injections it is likely due to baroreceptor action
what are the receptors in the ganglia?
nicotinic; respond to acetylcholine; stimulation of post-ganglionic nerves in both parasympathetic and sympathetic nervous systems; net effect of acetylcholine is increased blood pressure
what is the baroreceptor reflex?
in response to stretch detected in the baroreceptors in the carotids and aortic arch, baroreceptor primarily decreases cardiac output in order to lower blood pressure
what is the pathway of the baroreceptor reflex
neural signals from the baroreceptor are sent to the nucleus tracturs solaris in the brainstem via vagal afferents (and glossopharyngeal?) and cause vagal efferents to release acetylcholine on heart that decreases cardiac output; there is also a much smaller effect on sympathetic tone but this is minor
what occurs when there is decreased stretch detected in the baroreceptors?
vagal afferent firing slows and vagal tone on heart decreases and suppression of sympathetic firing decreases; sympathetic stimulation also raises blood pressure and cardiac output
where are the baroreceptors located?
in the aortic arch and in the carotid sinus
what is intra-arterial/direct blood pressure monitoring?
it is when a blood pressure catheter is inserted into the artery of an animal; generally the catheter tip is fluid filled and connected to a pressure transducer peripheral to the animal via fluid-filled tubing
another more expensive technology is a solid state pressure sensor inserted directly into the artery (millar catheter)
