13 Flashcards
whats the name of the tube that carries urine to bladder
ureter
whats the name of the tube that carries urine from bladder to outside world
urethra
which is above the order renal artery or renal vein
artery
what does the renal artery and veins branch to
interlobular arteries
interlobular veins
whats the final branch of renal arteries
glomeruli (many capillaries)
where are glomeruli found
cortex
what encloses glomerulus
bowman capsule (epithelium layer)
what type of capillaries are inside Romans capsule
fenestrated
whats the first stage of urine formation
filtering of plasma from the glomerular capillaries into the space of the capsule
where does the capsular space empty
proximal convoluted tubule
what percentage of the blood is filtered through glomerulus (filtration fraction)
20%
which arteriole has greater diameter afferent or efferent
afferent
is there a drop or an increase in pressure entre afferent and efferent
drop
what mechanism drives fluid through the capillaries endothelium to bowman space
filtration pressure caused by high pressure in afferent
function of podocytes and where re they found
control size of particles that can go out
glucose is filtered but protein are not
on festered capillaries of glomerulus
what can cause proteinuria
infection so podocytes inflamed so more space between them so proteins can get through
where in the kidney is the loop of hence
medulla
which is longer distal or proximal convoluted tubule
proximal
what makes up a nephron
bowman capsule proximal convoluted loop of H distal convol collecting duct
whats in urine but not filtered in bowman capsule how are they filtered
dyes nad antiobiotcs
secreted by peritubular capillaries near proximal convoluted tubules
whats the physical pressure in glomerular capillaries
55 mmHg
Net Filtration Pressure equation
NFP = (HP in capillaries - OP in capillaries) - (HP capsule- OP capsule)
physical pressure of fluid in capsule
15 mmHg
osmotic pressure in capsules
0 bc no proteins
Net Filtration Pressure in bowman capsule
10 mmHg
systemic cardiac output flows through the kidneys each minute
1.2 L/min
Glomerular filtration rate and normal value
The total amount of fluid filtered through ALL the glomeruli in BOTH kidneys in a fit adult is about
120-125 mL/min
Renal plasma flow and normal value
blood flow through kidney
680mL/min
normal urine flow for adult
1mL/min
how much of filtrated fluid appears in urine
1%
where does water reabsorption happen
proximal tubule mostly (2/3)
rest in loop of H and distal tubule
how does reabsorption happen
sodium is pumped out by NaK pumpkin BASAL SIDE
water follows
glucose follows
and goes to interstitial fluid d then to peritubular capillaries
which side of epithelial cells has the NAK pumps
basal
how to measure GFR
Clearence
measured in units of volume/time (litres/minute).
It is the effective volume of plasma completely ‘cleared’ of a substance per minute.
is mthg is not removed from plasma at all, whats the clearance
0
whats the clearance if smthg is Removed at same rate as water passes through glomeruli:
GFR
whats the clearance if smthg is Removed at same rate as water passes through glomeruli:
Completely removed from blood passing through kidney: Clearance = RPF
what happens to GFR if kidney is damaged
decreases
clearance measure equation
C= ( [Urine] / [Plasma] ) x [Volume of urine per minue]
clinically measure GFR
1) measure the concentration of the substance in the plasma,
2) collect urine for a fixed period to get the urine flow (ml/min), and
3) measure the concentration of the substance in the urine
gold standard of measuring GFR
clearance of creatinine BUT overestimates by 10 20% bc some is secreted.
why is creatine gold stsndard
bc steady state in blood
how can you get an approximation of kidney function
from blood creatinine concentration
how can you measure renal plasma flow
clearence using paraaminohipuric acid bc its completely secreted
*Normal creatinine clearance:
women 88-128 mL/min:
men 97 to 137 mL/min.
does GFR change with changes in BP
NO
its auto regulated
does Renal blood flow change with changes in BP
NP
kidney blood flow is controlled
by kidney itself (EPO)
Explain the auto regulation of the kidneys
The GFR is regulated by the balance of constriction in the smooth muscle of the afferent and efferent arterioles; this maintains GFR constant despite changes in systemic blood pressure
The constrictor tone in the efferent arterioles is higher than in the afferents, producing a filtration pressure in the glomerulus.
If the afferents constrict and the efferents relax, this lowers the the filtration pressure and thus GFR
if the afferents relax and the efferents contract, this raises filtration pressure and GFR
The balance between the constriction in afferent and efferent arteriolar smooth muscle is controlled by
the juxtaglomerular apparatus. This is a structure where the distal tubule folds back and contacts the glomerulus at the point where the afferent and efferent arterioles enter.
Cells in the macula densa functions
Detect the concentration of sodium in the distal tubular fluid. If sodium levels are low, this indicates that GFR is too low. The macula densa releases local chemical factors (adenosine & ATP) which relax the smooth muscle in the afferent arteriole, thus increasing the filtration pressure and increasing GFR. Conversely, if the GFR is too high, the macula densa releases chemical factors which constrict the the afferent arteriole, decrease filtration pressure and reduce GFR.
hypothetical gold standard
inulin
normal RPF both kidneys
600-700 mL/min
