Blood Pressure Flashcards
systolic BP
pressure in arteries during contraction
diastolic BP
pressure in arteries during relaxation
sphygmomanometer
measures BP by occluding an artery of extremity e.g arm with an inflatable cuff
korotkoff sounds
blood flow sounds
baroreceptors
mechanoreceptors that detect the degree of stretch in blood vessel walls
where are baroreceptors most abundant
in the aortic arch and carotid sinus
what nerve innervates the carotid sinus baroreceptors
sinus nerve of hering (branch of glossopharyngeal)
what nerve innervates aortic arch baroreceptors
aortic nerve
what baroreceptors have a higher threshold to pressure
aortic arch therefore they are less sensitive than carotid sinus baroreceptors to changes in stretch
how to baroreceptors influence a change in arterial pressure
1 - barorecpetors detect and increase /decrease in pressure resulting in an increase/ decrease in the APs they fire
2. - this info travels along afferent neurons to CV centre in medulla
3 - medulla then increasing stimulation of either the parasympathetic NS or the sympathetic NS
valsalva manoeuvre
attempt to expire against closed airways
raises BP and HR
why are baroreceptors regarded as only short term regulators of blood pressure
if there is a prolonged increase in BP the threshold of baroreceptor firing will also increase
what is a long term regulator of blood pressure
blood volume
an increase in blood volume sees an increase in blood pressure
however
an increase in blood pressure sees a decrease in blood volume via increased renal excretion of salt and water
(negative feedback loop)
how is local control of blood pressure achieved
by changing arteriole radius
to decrease radius - sympathetic nerves release noradrenaline thats bind to alpha 1 adrenoreceptors
to increase radius - sympathetic nerves release noradrenaline that binds to beta 2 adrenorecpetors
hypertension
high blood pressure characterised by 140/90 mmHg or higher
