101314 HTN Flashcards
if supine and standing NE concentrations are the same, what does this indicate?
arterial baroreceptors are dysfunctional
arterial pressure = ?
cardiac output x total peripheral resistance
what does short term regulation of BP consist of?
renin on peripheral resistance
increased HR
ADH and aldoesterone on increasing vascular volume, venous return, and CO to increase BP
nervous regulation plays a role in what with regards to the circulation?
redistribution of blood flow to different areas
affects HR and contractility
essential for the very RAPID control of arterial pres
where is the vasomotor center located?
reticular substance of medulla and lower third of pons
sympathetic innervation excludes which blood vessels?
capillaires and precapillary sphincters and some meta arterioles
parasympathetic nerv sys mainly controls what?
HR via vagus nerve
sympathetics are responsible for what tone?
vasomotor
baroreceptor signals from carotid sinus are transmitted to what nerve?
glossopharyngeal, to the nucleus tractus solitarii of medulla
baroreceptor signals from aorta are transmitted by which nerve?
vagus nerve
baroreceptor pressure control system
when arterial pressure goes up, baroreceptors sense and signals to CNS. get feedback to lower the pressure.
when common carotids are constricted so they can’t sense pres, the lowered pressure causes CNS to increase the arterial pressure
feedback gain
G represents strength of feedback
G is equal to correction of error signal over the error or abnormality that remains
as pressure increases in the carotid sinus, what happens to carotid sinus firing?
it increases
however, below 60 and over 180 mmHG, carotid sinus baroreceptors no longer respond
what do baroreceptors respond to?
rapid arterial pressure CHANGES
relationship btwn carotid distending pressure and muscle sympathetic nerve activity and cardiac R-R interval
as carotide distending pres increases, R-R interval increases, and muscle sympathetic nerve activity decreases
main role of baroreceptors
to stabilize changes in BP
if BP is higher for long period of time, what can happen with baroreceptor?
it can reset so that the new BP becomes baseline
what are AT1 receptor mediated effects?
vasoconstriction
fibrotic
inflammatory
antinatriuretic
HTN
what are AT2 receptor mediated effects
opposite of AT1
ROS plays a role in HTN: true or false
true
hypertension is more prevalent among what groups
elderly above 60 (largely systolic)
African Americans
what is considered pre-HTN
systolic: 120-139
or
diastolic: 80-89
stage 1 hypertension values
140-159 for systolic, or 90-99 for diastolic
how is HTN diagnosed?
if the average of at least 2 readings per visit obtained at 3 separate visits each 2-4 wks apart is 140 mmHg or greater for systolic and 90mmHg or greater for diastolic
age differences in terms of systolic vs diastolic HTN
if older, you see most cases of untreated HTN are isolated systolic HTN
if younger, many cases of untreated HTN are isolated diastolic HTN
essential HTN causes
polygenic and multifactorial (environment)
what are most cases of HTN caused by
essential HTN (90% of cases)
clinical clues include: onset at 20-50 yrs, family hx of HTN, normal serum K and urinalysis
forms of HTN can be divided into two forms-what are they?
primary genetic forms
secondary forms
comorbidites of HTN
atherosclerosis CAD MI stroke congestive heart failure peripheral vascular disease
chronic kidney disease obesity diabetes metabolic syndrome obstructive sleep apnea cognitive impairment
long term regulation of BP is controlled by
kidney-mass balance of sodium and water
what are general determinants of the pressure-natriuesis relationship
vascular resistance
GFR
tubular reabsorption
what happens in a salt sensitive model of HTN?
you require higher pressures to achieve similar Na/H2O excretion rates as control
in experiments, found that when angiotensin II levels are increased, the slope of the pressure-natriuresis relationship is reduced
what happens when you remove the kidney to pressure-natriuresis relationshiP?
the slope gets shifted down and to right
as age increases, what is the contribution of CO and TPR to essential HTN?
TPR contribution increases
CO contribution decreases
what happens to the pressure-natriuresis relationship in hereditary forms of HTN?
the slope is reduced
what is the possible mechanism of salt sensitive HTN?
too much Na reabsorption due to genetics
what are the main downstream effects of HTN?
increased afterload
arterial damage, leading to accelerated atherosclerosis or weakened vessel walls
