glomerular function Flashcards
4 major functions of kidneys
- excrete nitorgenous waste
- regulate volume
- synthesize hormones (renin, EPO)
- excrete exogenous compounds
what is fucntional unit of kidney
nephron (glomerulus + tubule)
what is filtering unit of kidney
glomerulus
what is reabsorption unit of kidney
tubule
what is blood path through kidney
renal art>smaller art>afferent arterioles>glom>eff arterioles>peritubular caps>small veins>renal veins
what percent of CO is renal blood flow
20% of 5l/min = 1L per min
what is renal plasma flow
60% of blood so 0.6L/min
how much of renal plasma flow is filtered
20%
what is glomerular filtration rate
rate at which fluid is filtered from glom to bowman’s (120ml/min)
4 determinants of GFR
- cap surface area
- hydrostatic and oncitic pressures
- renal plasma flow (BP and afferent art resistance)
- efferent arteriolar resisitance
what is filtration fraction
GFR/RPF
what is general flitration fraction value
20% and constant, so if RPF rises, so does GFR
what is renal blood flow formula
art BP/vasular resistance
how do afferent arterioles regulate BP
as BP goes up, they constrict to reduce flow and keep constant
3 things that affect aff resistance
- autoregulation
- sympathetics - constrict
- prostaglandins - dilate
within what pressure does GFR remain constant
80-180mmHg
what are 4 effects of prostaglandin on kidneys
- vasodilation
- incr renin
- antagonize ADH
- excrete Na
what is effect of ASA and NSAIDs on prostaglandin
inhibit COX - not prostaglandins
what will overall effect of ASA and NSAIDs be
extra reduction in renal blood flow
what is effect of efferent arteriole resistance
increased pressure in GC and thus reduces filtration rate
what gets filtered and what doesn’t
does: water and small solutes
doesn’t: large proteins
what are 3 structural filtration barriers?
- endothelium
- glomerular basement membrane
- epoithelium
2 main classes of kidney disease
- acute
2. chronic
3 types of acute disease
- decreased perfusion
- blockage to urine flow
- acute damage to kidney tissue
4 types of chronic renal disease
- metabolic - DM scarring
- autoimmune - glomuerulonephritis
- vascular - BP
- genetic - polycyctic kidney
what are 3 options to measure Cr
- Calculate GFR using 24 hour collection
- compare plasma Cr to previous levels
- use equatiosn
what is Cr
waste product made from muscle
what is plasma [Cr] formula
muscle/kidneys
what % of delivers Cr is filtered
20%
how much filter Cr is excreted
100%
what does Cr excreted =
urine [Cr] x urine vol/day
what does Cr filtered =
plasma [Cr] x GFR
** what does GFR =
(urine[Cr] x vol or urine/day)/plasma[Cr]
what happens to plasma [Cr] if GFR goes down
will go up until hits stready state
what is GFR compared to plasma [Cr]
GFR = 1/plasma [Cr]
how do you know when steady state acheived
no changes in plasma [Cr] over 2 days
what happens to GFR is plasma has gone up 3x
1/3
