hypertension Flashcards
what is hyper tension?
elevated blood pressue
stage 1 is 140-159/90-99
stage 2 is above that
What can hypertension lead to
heart disease
kidney disease
strokes
what is primary hypertension
HTN with no identifiable cause
diagnosis made by ruling out possible other causes
chronic and progressive
92% of cases of HTN are primary
what is secondary hypertension
elevation in bp brought on by identifiable cause.
ex renal diesease, oral contraception
may be pausible to treat cause instead of using meds
What are the two ways to reduce BP
implement healthy lifestyle choices
use antihypertensive meds
what are the primary factors affecting bp
blood volume - fluid loss due to dehydra stion or fluid retention due to aldosteron and ADH
peripheral resistance/diameter of atrioles
what systems regulates blood pressure?
sympathetic nervous system
RAAS or renin-angiotensin-aldosterone system
the kidney
how does the sympathetic nervous system regulate bp
using sympathetic baroreceptor reflex
baroreceptors in specific blood vessels send info to cns
when bp is low, brain sends impulse through sympathetic nerves to stimulate heart and blood vessels
bp is elevated by beta-1 receptors in heart
activation of vascular alpha 1 receptors leads to vasoconstriction
this mechanism often opposes drug therapy because of “set point” used to make judgement of what’s high or low this set point is reset to “new normal” after time
how does renin-angiotensin-aldosteron system regulate bp
elevates bp
kidney tissue releases renin in response to: reduced blood flow, volume or pressure
beta 1 receptors on cell surface activated
renin catalyzes angiotensinogen to angiotensin 1, which is a weak vasoconstrictor
then angiotensin converting enzyme (ACE) acts on angiotensin 1 to make angiotensin 2 and further constrict blood vessesl
note angiotensin 2 causes retention of sodium and water
how does the kidney regulate bp
when bp falls, glomerular filtration rate or GFR aslo falls
this promotes retention of sodium, chloride and water as well as increases blood volume
increased blood volume increases venous return, increasing cardiac output then arteriol pressure
this is counteracted with diuretics
drug therapy to lower bp works by
reducing heart rate myocardial contractility blood volume venous return tone of arteriolar smooth muscle
prinicple site where antihpertensives act is?
brainstem
decreasing sympathetic outflow to heart and blood vessels resulting in decreased heart rate, decreased myocardial contraction, and vasodialation
whats up with sympathetic ganglia
rarely used are ganglionic blockade because it works so well at reducing sympathetic stimulation of the heart it sometimes stops
what are the three classes of beta blockers
first generation or nonselective beta blockers
second generation or cardioselective beta blockers
third generation or vasodialating beta blockers
what kind of beta receptors are there and where are they located where?
beta 1 on cardiac and some on renal tissue
beta 2 on lungs
