Diuretics lecture Flashcards
arterial BP=
cardiac output and peripheral vascular resistance
cardiac output depends on:
myocardial contractility & ventricular filling pressure
ventricular filling pressure depends on:
blood volume and venous tone
vascular resistance depends on:
state of SMC (contracted/relaxed) and activity of systems that control the diameter
blood volume is the primary target of
diuretics- by decreasing blood volume
main function of the kidneys:
maintain normal body fluid volume & electrolyte balance
filtration rate under normal conditions
~120ml/min
how much of the filtered fluid & electrolytes are reabsorbed?
~99%
urine output rate:
1ml/min
what is the basic urine-forming unit?
the nephron
what part of the nephron deals with filtration?
glomerulus
what part of the nephron deals with reabsorption & conditioning?
tubule
what supplies blood to the nephron
afferent arteriol
what removes blood from the nephron
efferent arteriole
where is reabsorption the greatest?
proxima; tubule & declines distally toward collecting duct
how much Na is reabsorbed in the proximal tubule?
65%
how much Na is reabsorbed in the loop of Henle?
25%
how much Na is reabsorbed in the early distale tubule & distal convoluted tubule?
5%
what is a major determinant of extracellular fluid volume?
NaCl
diuretics increase the rate of urine flow and:
NaCl excretion (& water)
diuretics initial effects
incr. NaCl excretion-> decr. extracellular fluid volume-> decr. venous return-> decr. cardiac output-> decr. BP