Urinary System Flashcards
what is the primary function of the kidneys
blood filtration
what medication is used for high BP?
ACE inhibitor
which kidney is more susceptible damage?
the right kidney
where in the kidneys is urine produced?
in the cortex and medulla
what is the major unit in the kidney that produces urine?
nephron
what makes up the renal corpuscle?
glomerulus and glomerular capsule
flow through renal tubule
renal corpuscle–> proximal convoluted tubule–> nephron loop (descending and ascending limb)–> distal convoluted tubule–> collecting duct
what are the 2 classes of nephrons?
cortical and juxtamedullary
what are cortical nephrons?
85% of nephrons
almost entirely in the cortex
short loop
barely crosses into the medulla
what are juxtamedullary nephrons?
long nephron loops deeply invading the medulla
ascending limb-thick and thin
concentrated urine
glomerulus is closer to junction
vasa recta
pressure in the glomerulus
high BP
fed and drained by arterioles
pressure in the peritubular capillaries
low pressure
empty into venules
porous for absorption
arise from efferent arterioles
what is the juxtaglomerular complex?
each nephron has one
distal ascending limb of the nephron loop and afferent arteriole
important in regulating the rate of filtration formation and BP
urine formation
glomerular filtration: produces cell and protein free filtrate
tubular reabsorption: selectively returns 99% of substances of filtrate to blood in renal tubules and collecting ducts
tubular secretion: selectively moves substances from blood to filtrate in renal tubules and collecting ducts
glomerular filtration
produces cell and protein free filtrate
passive, high pressure to low pressure or volume
hydrostatic pressure forces fluids into glomerular capsule
fenestrated filtration b/w blood and capsule
outward pressure
promotes filtration
hydrostatic pressure in glomerular capillaries (HPgc) is about 55 mmHg
inward pressure
inhibits filtrate formation
hydrostatic pressure in capsular space (HPcs) is about 15 mmHg
colloid osmotic pressure in capillaries (OPc) is about 30 mmHg
what is net filtration pressure?
sum of all forces
main controllable factor determining glomerular filtration rate (GFR)
ex: 55 - (15+30)= net outflow of 10 mmHg
pressure from afferent to glomerular
passive
pressure from capillaries to proximal convoluted tubule
HP in glomerular becomes high and pushes fluid into tubules
what is glomerular filtration rate?
volume of filtrate formed per minute by both kidneys
indicates health of kidneys (glomerulus and corpuscle)
intrinsic controls of GFR
myogenic mechanism
tubuloglomerular feedback mechanism
what is the myogenic mechanism?
smooth muscle contracts when stretched
increased BP=stretch=restricts flow to glomerulus
decreased BP=dilation
what is the tubuloglomerular feedback mechanism?
increased GFR+increased filtrate flow=decreased reabsorption time=increased NaCl in filtrate
feedback=constrict afferent arteriole=decreased NFP, decreased GFR=more time for NaCl reabsorption
what are the extrinsic controls of GFR?
SNS and RAAS
what is the SNS control in GFR?
NE released by SNS and E released by nervous and endocrine functions
vasoconstriction, increased BP, increased BV
constrict afferent arterioles=decreased GFR
what is the RAAS control in GFR?
main mechanism for increasing BP
renin released by granular cells
drop in BV will cause the DCT to ___ fluid
reabsorb
increased in BV will cause the DCT to ___ fluid
empty
low BP/Bv leads to…
DCT will reabsorb more water with the help of aldosterone and ADH
reabsorption of more sodium (water follows sodium)
high BP/BV leads to…
stretch in atria which triggers release of ANP
ANP inhibits the release of ADH and aldosterone (helps lower BP)
