Renal: GFR Flashcards
of all cardiac out put how much goes through both kidneys? each kidney?
of 5L, 1L in both kidneys, 500 ml in each (per min)
where are the inter vs intra lobular arteries
inter sits on top of the lobe, intra sits between the lobes
where is the arcuate artery
lies parallel on top of the lobe
where is the glomerulus
the bulbs on the ends of the afferent arterioles
where is the nephron
sticking out of the lobe, its head connects with the glomerulus
the afferent and effernt arterioles lead into where
the glomerular capillary that sits inside bowmans space
where does the glomerular capillary lie
inside bowmans space
what is PGC and what does it do
glomerular capillary pressure: pushes fluid from caps into bowmans space
what is PT and what does it do
tubular hydrostatic pressure: pushes fluid from bowmans space back into cap
what is oncotic pressure and what does it do
pressure from albumin, keeps water in the capillary space
what is the ultrafiltration coefficient and what does it do
the area available for filtration to occur (the permeability)
what is plasma flow
the continuous flow of plasma; the most important factor in the gfr
what happens to pressure of filtration as the glomerular cap length increases
ultrafiltration pressure decreases, because the long the glom cap, the lower the plasma flow at the bottom, the higher the albumin, the higher the oncotic pressure, the lower the pressure out
how to calculate single nephron gfr
permeability (kf) x ultrafiltration rate (ultrafiltration is hydrostatic pressure gradient - oncotic pressure gradient)
how does kf impact gfr
kf inc, gfr inc
how does ultrafiltration pressure impact gfr
uf inc, gfr inc
how does oncotic pressure impact gfr
onc inc, grf dec
how does plasma flow impact gfr
plasma flow inc, gfr inc
what is the most important determinant of gfr
plasma flow
how much gets filter by the glomerulus per minute? per day
100 -120 ml/min, 150-170 L/day
what determines renal blood flow
blood pressure (arterial), renal vascular pressure
what happens to the afferent arteriole if bp falls vs rises? why?
falls, AA dilates: maintain renal blood flow
rises, AA constricts, to maintain normal renal blood flow
the myogenic reflex in afferent arteriole does what
vasoconstricts and dilates the afferent arteriole
what is tubuloglomerular feedback? is it myogenic?
its feedback from the tubules that alerts the afferent arterioles to constrict under cases where you have too much salt, and want to reduce the
GFR, it is not myogenic
describe the tubuloglomerular feedback pathway
high na, adenosine released, causes AA contraction, more AA resistance, less plamsma flow, less GFR
what happens when efferent arteriole has increased resistance
the macula densa cells can respond to sodium in the thick ascending limb and DCT. if there is too much, they’ll stimulate adenosine release.
adenosine causes muscular contractin in afferent arteriole
increased relasistance
less blood flow
less gfr
what does angiotension 2 do to efferent arteriole
causes increases resistance in efferent to increase hydrostatic pressure and gfr
qa gets impacted by the ____ arteriole. hydrostatic pressure gets impacted by the ____ arteriole
afferent, efferent
what is convection
movement of small solute with bulk flow of water
what solutes are freely filtered in the kidney ? why?
theyre small enough that they can go through, and provide the kidney with substrates to use
na, l, cl, glucose, bicarb, urea, creatinine
why does the kidney need to be perm selective
so it doesnt lose the big molecules it needs
is the glomerular cap more restrictive to neg or pos charged mols
negative
how much macromolecule does a healthy person excrete
less than 10mg/24h
why is gfr measured
to measure kidney fucntion
how (generally) is gfr measured
using a freely filtered solute, so that solute clearance = gfr
how does inulin measure gfr? what are the cons?
once inserted in, no resorption, but has to be given intravenously
how does creatinine measure the gfr
free filtration, collect urine for 24h
creat clearance = urine flow rate x [urine creat]/[plasma creat]
explain relationship between gfr and plasma creat
inversely prop
what are healthy total protein and albumin measurements in the urine
<0.15g/24h, <30mg/24h
describe what happens to protein in urine as diabetes develops. why?
too much protein in urine bc glom filtration doesnt work as well.
