control of blood pressure Flashcards
what must arterial BP be maintained at?
120/80
what are the 4 main control systems involved in controlling BP?
. arterial BP
. CO
. local circulation & blood
. extracellular fluid volume
what are baroreceptors?
sensors located in blood vessels that sense BP and relay the info to the brain to maintain proper BP
clusters of arterial baroreceptors are found in 2 locations, what are these?
aortic arch and carotid sinus
which nerve carries information from the carotid sinus baroreceptor?
hering branch of glossopharyngeal
which nerve carries information from the aortic arch baroreceptor?
vagus
what do baroreceptors respond to?
stretching (pressure change)
which baroreceptor is more sensitive and therefore more important?
carotid sinus
which part of the brain receives inputs from baroreceptors?
nucleus tractus solitari
when are baroreceptors active?
when blood pressure rises
describe the series of events that follow a drop in BP?
. NTS activates B1 receptors which inhibit vagal nucleus and stimulate bulbar circulatory centre
. inhibition of vagal nucleus leads to reduced ACh acting on M2 receptors, increasing CO
. activation of bulbar circulator centres increases NA which activates a1 receptors on arteries increasing peripheral resistance
. Increase in NA also acts on b1 in heart, increasing CO
describe the series of events that follow a rise in BP?
NTS activates a2 receptors which activate vagal nucleus and inhibit bulbar circulatory centre
. activation of vagal nucleus leads to increased ACh acting on M2 receptors, decreasing CO
. inhibition of bulbar circulator centres decreases NA which reduces activation of a1 receptors on arteries decreasing peripheral resistance
. decrease in NA also acts on b1 in heart, decreasing CO
what does a clonidine a2 agonist do and what is a problem associated with it?
reduce BP but causes rebound hypertension
what does a-methylopa do?
reduce hypertension in pregnant women
what does nicorandil do?
treat angina
how does the sympathetic NS constrict arteriolar radius?
produces NA which acts on a1 to constrict
how do sympathetic cholinergic nerve dilate arteries?
produce ACH which acts on muscarinic receptors
how does adrenaline dilate arteries?
acts on b2 receptors
what is capillary shift?
the movement of fluid across the capillary membrane between the blood and the interstitial fluid compartment.
at which point of the day is BP greatest?
waking
at which point of the day is BP lowest?
sleeping
give an example of something that increases BP?
exercise
what effect does ageing have on BP?
increases
what is hypertension?
hight BP
give examples of secondary hypertension causes
. renal hypertension
. phaeochromocytoma
. aortic coarctation
. drug induced
give examples of secondary hypertension causes
. salt intake
. cigarettes
. genetic predisposition
. stress
what damage may hypertension cause to the CVS?
. thickening of arteries
. deterioration in atherosclerosis
. aneurysms in central arteries
. left ventricular hypertrophy
what CVS diseases can hypertension lead to?
. malignant hypertension . stroke . renal disease . cardiac hypertrophy . cardiac ischaemia and angina
what treatments are used to treat hypertension?
beta-adrenoreceptor antagonists, Ca channel blockers, alpha blockers, ACE inhibitors, diuretics, clonidine, methyl-dopa
