Cardiovascular Regulation Flashcards
which receptors are involved in MAP regulation
baroreceptors
cardiopulmonary stretch receptors
chemoreceptors
what do baroreceptors detect
increase in bp
where are the baroreceptors found
outer layer of the arterial walls in the carotid sinu and aortic arch
which factors increase MAP
increase in CO
increase in SVR
what does SVR stand for
systemic vascular resistance
which factors increase SVR
length of blood vessels
viscous blood
vasoconstriction
what is the effect of baroreceptors being stimulated at high bp
high MAP= baroreceptors detect stretch, stimulate the afferent nerves project in cranial nerves 9/10 going to the medulla oblongata= increase in efferent parasympathetic stimulation of heart= bradycardia (slow HR)
what is the effect of baroreceptors being stimulated at low bp
low MAP= baroreceptors detect no stretch= increase in sympathetic stimulation of heart (increase CO) increase in adrenaline (vasoconstriction)
what hormones causes vasoconstriction
adrenaline
what hormones causes vasodilation
noradrenaline
nitric acid
why is the baroreceptor a rapid acute buffer in homeostasis of MAP
- the latency of vagal bradycardia is short
- quick stimulation to sympathetic vasomotor nerve
what is the biggest challenge to the CV system
orthostasis
what is orthostasis
the effect of gravity on the distribution of VENOUS BLOOD
postural changes- bp drops all of a sudden
what is cerebral perfusion
the pressure in brain
hypo-perfusion= low bp in brain
how do the baroreceptors maintain normal cerebral perfusion
barorecptors in the carotid sinus detect the low bp= reduce the vagal outflow to the heart, and increase the outflow in sympathetic cardiac and vasomotor nerves
what is cerebral ischemia
low blood flow to brain
how do the chemoreceptors prevent cerebral ischamia thus maintain normal cerebral perfusion
low blood flow to brain= co2 accumulates and pH decreases= detected by chemoreceptors= increase in sympathetic outflow and more vasoconstriction= blood directed to brain
what is Cushing’s reaction
when the chemoreceptors detect the cerebral ischemia and respond
what do chemoreceptors detect
the changes in chemical composition of arterial blood: H+, CO2, h20
where are the chemoreceptors located
close to baroreceptors (carotid sinus, aortic arch)
effects of chemoreceptors
- cushings reaction (cerebral perfusion)
- sympathetic fibres= vasconstriction
- respiratory centre= increase rate/ depth of breathing= lung inflation reflex = increase HR
what do chemoreceptors respond to
hypoxia
hypercamia
acidosis
what do cardio-pulmonary stretch receptors detect
low(er) bp than baroreceptors
what is the effect of cardio-pulmonary stretch receptors at low bp
to increase the blood volume and reduce fluid loss via..
- release of anti-diuretic hormone, ADH
- constriction of renal arterioles (kidney/gut)= decrease rate of glomerular filtration
what does the release of ADH do
ADH= increases reabsorption of fluid from renal tubules
= produces concentrated urine
both increase blood volume
how does the kidney maintain arterial pressure
controls blood volume via reinin- angiotensin-alodosterone system
NB. aldosterone is a hormone which increases blood volume
