physiology of blood pressure Flashcards
formula for mean systemic arterial (MAP)
MAP=COxTPR
what does autonomic control influence (BP related)
cardiac output and vascular resistance
what does long term response in kidney influence BP related
vascular resistance
what is the fundamental role of the kidney
- filtration
- reabsorption
- excretion
what is glomerular filtration rate
a test that estimates how much blood passes through the glomeruli each minute (how well the kidneys work)
what are the three basic renal processes
- glomerular filtration
- tubular reabsorption
- tubular secretion
is GFR usually high or low
very high, around 180L/day
means there’s lots of opportunity to regulate EFC composition and get rid of unwanted substances
is it the EFC that is regulated or the urine
the EFC
do kidneys have good or bad blood supply
really good
0.5% total body weight but 20% of CO
what does GFR regulate
hormonal release
what does the macula densa do
senses GFR by Na+
what does the juxtaglomerular (JG) apparatus include
JG cells that secrete renin
what are the most important hormones involved in the control of BP
- ADH (vasopressin)
- angiotensin II
- aldosterone
- atrial natriuretic peptide (ANP)
what is the principal facto controlling Ang II levels
renin release
how does decreased circulating Ang II volume stimulate renin release
through
- decreased BP
- decreased NaCl at macula densa
- decreased renal perfusion pressure
important actions of angiotensin II
- stimulation of aldosterone release from adrenal cortex
- vasoconstriction of renal and other systemic vessels
- enhanced tubuloglomerular feedback (makes macula densa more sensitive)
- enhance Na-H exchanger and Na channel to promote Na reabsorption
- renal hypertrophy
- stimulates thirst and ADH release by acting upon hypothalamus
what does aldosterone stimulate
Na reabsorption and K excretion by the renal tube
what does aldosterone exert
indirect negative feedback on RAAS by increasing ECV and by lowering plasma (K)
what is aldosterone really important for
conserving Na and water
preventing massive swings in K levels
what is the primary importance in blood pressure (kidneys)
RAAS
what activates RAAS
reduced blood flow
what causes loss of control of blood pressure (kidneys)
- renal and renovascular disease
- decrease in kidney blood flow (GFR)
- inappropriate activation of RAAS
what does angiotensin II cause
- direct constriction of renal arterioles
- aldosterone synthesis
what does deceased pressure in renal arterioles and sympathetic activity cause
renin production which causes angiotensin II production
what does reduction in renal pressure cause
intrarenal redistribution of pressure and increased absorption of salt and water
