physiology 4 - long/short term control of BP Flashcards
what happens if MAP is too high
hypertension
what happens if MAP is too low
Syncope
what are two types of arterial baroreflex
aortic arch baroreceptors
carotid sinus baroreceptors
where to the baroreceptors go to
the brain
what signals do arterial baroreceptors send to the brain - why is this important
there is a normal firing rate any slower (less) = lower BP any faster (more) = elevated
what nerve passes information from the carotid sinus baroreceptors
the glossopharyngeal nerve
what are the inputs to the medullary cardiovascular centres
Cardiopulmonary baroreceptors
Central
chemoreceptors
Chemoreceptors in muscle
Joint receptors
Higher centres
what does Regulation of blood pressure
in the long term revolve around
Revolves around blood volume
what controls long term blood pressure - what effects
the main sensors are the cardio-pulmonary baroreceptors
effects tend to be hormonal
what does the long term regulation of blood pressure act on
the blood vessels and kidneys
what are the two types of posture effecting blood pressure
effect of standing
the reflex tone
what does the vasopressin do
increase water permeability of the collecting duct - increasing plasma volume
also increase TPR
what is the Valsalva maneuverer
forced expiration against a closed glottis
what happens during the Valsalva maneuverer
thoracic pressure increases - causing a decrease in venous return
what does the wave of the Valsalva maneuverer work
sharp up, slowly down, sharp down, then up
what does a decrease in Venous return lead to
decrease in EDV leading to decreased stroke volume, decreased Co and then in turn a decrease in MAP
what dose the decrease in MAP lead to
detected by baroreceptors - increase CO and TPR
what happens after the thoracic pressure is reduced
its transmitted through the aorta - and drops the BP
what happens after the BP drops after reduced thoracic pressure
venous return is restored - stroke volume is restored, there’s a bit of a hump as the reflex effects hadn’t worn off
what does angiotensin 2 do
cause arterial constriction -
what does aldosterone do
increase Na+ reabsorption
therefore increase plasma volume - and increase BP
what are the 3 hormonal long term controls
renin-angiogenesis-aldosterone system
antidiuretic factor (ADH, vasopressin)
atrial natriuretic peptide
how do the kidneys regulates plasma volume
controlling the Na+ gradient
control over the permeability of the collecting ducts
determines how much water is retained
what happens of the collecting duct is very permeable
it will result in conservation of water and in turn plasma volume
what happens if the collecting duct was very impermeable
water will result in little reabsorption, lots of urine (= diuresis)
how does the water move in and out
depending on the Na+ permeability creating hyper/hypo osmotic
where is renin produced
the juxtaglomerular = granule cells of the kidney
what triggers renin production
decreased distension of afferent arterioles
decreased delivery of Na+ through tubule
all signs of low MAP
what does renin do
converts inactive angiotensinogen to angiotensin 1
what does angiotensin 1 become
what facilitates it
angiotensin 2
angiotensin converting enzyme
what does angiotensin 2 do - what is it
stimulates released of aldosterone from the adrenal cortex
increase release of ADH from pituitary
is a vasoconstrictor
negative feedback system in response to decreased MAP
what is ADH
antidiuretic hormone
where is ADH made/released from
synthesised in the hypothalamus
released from the posterior pituitary
what does ADH do
increase water permeability of the collecting duct to H2O
reduces diuresis and increases plasma volume
what is ADH alternative name
vasopressin
causing vasoconstriction - increasing MAP
what triggers ADH release
a decrease in blood volume
circulating angiotensin 2
what does aldosterone do
increases Na reabsorption in the loop of henle
reduces diuresis
where is aldosterone produced
from the adrenal cortex
where is ANP produced
Produced in, and released from myocardial cells in the atria
what does ANP stand for
Atrial natriuretic peptide
what triggers atrial natriuretic peptide - what is this a sing of
increased distension of the atrium - a sing of increased MAP
what does ANP do
increases excretion of Na+
inhibits the release of the renin
reduces MAP
what is ANP
a negative feedback system
reduces MAP
how many cases of hypertension are there
5-10%
what are the treatments for hypertension
Ca2+ channel antagonists
beta adrenoceptor antagonists
thiazide diuretics
angiotensin converting enzyme inhibitors
