Long-term Control BP Hypertension - IN Flashcards
what is the set point for BP (generally)
hypotension would be systolic under 90, and hypertension would be systolic over 140, but everyone has their own normal set point
what can make BP vary
age, time of day, stress, fever, exertion
what is the equation for BP
CO x PVR
what are the main factors influencing BP
cardiac output, peripheral resistance and blood volume
what is the fast factor that controls BP
baroreceptor reflex
what is the intermediate factor that controls BP
renal actions, causing changes in PVR
what is the slow factor that controls BP
renal salt and water excretion, mainly handled by Angiotensin II
whats the primary purpose of the juxtaglomerular apparatus
to help control BP
what does the macula densa do
senses changes in osmolarity, Cl-
what do juxtaglomerular granular cells do
produce renin
what does a decline in BP cause
release of renin, which leads to release of AII, which stimulates ADH, which increases water reabsorption
what does aldosterone do
stimulates proximal Na-H exchange, increasing Na/water reabsorption, and kicking out K. Decreases urine volume and increases BP/volume.
what causes an increase in Na reabsorption
cortisol, estrogen, GH, TH and insulin
how do primary hyperaldosteronism patients present
very low potassium and hypertension
what are the determinants of renin secretion
neural baroreceptors signal via renal sympathetics to granular cells
stretch receptors within afferent arterioles, which can function without innervation
NaCl delivery to macula densa, osmotic swelling releases transmitter to inhibit renin secretion
what does tubuloglomerular feedback accomplish
afferent arteriole constricts when confronted with too high GFR, putting break on the process.
lets talk about CHF v COPD
those with CHF will have high BNP b/c their blood volume is increased (BNP is a naturetic peptide involved with inhibited renin and relaxing afferent arteriole; leads to diuresis). In pt with GI bleeds, antidiuretic hormones can be given to increase water resorption and inc blood pressure (since it will vasoconstrict blood vessels).
what controls water excretion, and where
ADH in the distal nephron
what does the proximal nephron regulate
ECF
how does the proximal nepron regulate ECF
BP - if it falls, ADH increases to increase water resorption, increasing total body water and blood volume
what happens when you eat too much salt
osmolarity increases, fluid is expanded, therefore you decrease ADH to decrease water resorption and urinate more to try and balance it, reducing volume, TBW
