B5-040 Renal Physiology III Flashcards
plasma minus protein
ultrafiltrate
functional unit of kidney
nephron
triple layer of glomerulus
- endothelial cell
- basement membrane
- podocytes
factors involved in filtration
3
- size/charge of molecules
- properties of membrane (surface area, permeability)
- forces (GHP, COP, CHP)
how is GFR regulated?
2 mechanisms
- autoregulation
- extrinsic
main function is reabsorption
all is Na+ dependent
proximal tubule
2nd reabsorptive phase
works to concentrate or dilute urine
loop of Henle
which part of the tubule is aldosterone regulated?
distal tubule
which part of the tubule is ADH regulated?
collecting tubule
product of protein metabolism in liver
urea
why is BUN more a marker of tubule function?
depends on urea transporters
regulation of urea is closely linked with
ADH
where can uric acid accumulate?
joints –> gout
heart valves –> valve disease
kidneys –> kidney stone
urine output < 50 ml
anuria
urine output of 300-500 ml/day
oligouria
urine output > 3L/day
polyuria
ECF osmolarity depends on
Na+ concentration
main regulator of water reabsorption/secretion
hormone
ADH
ECF volume depends on
total body Na+ content
what part of the pituitary secretes ADH
posterior
ADH targets the
collecting duct
water reabsorption
ADH effect on urine
increased osmolarity
decreased volume
describe the regulation of ECF osmolarity through the hypothalmus
high ECF osmolarity
- ECF osmolarity increases
- triggers osmoreceptors in thirst center of hypothalmus
- triggers ADH release from posterior pituitary
- ADH acts on collecting tubule to increase water reabsorption
- more water enters plasma, decreases osmolarity
- promotes water reabsorption
- causes vasoconstriction
ADH
the circulating concentration of ADH is directly linked to
serum osmolality
slight changes in osmolality effect ADH concentration
[…] changes in pressure are needed to ellicit change in ADH
small or big
big
10%
ADH binds to […] receptors in the kidney
V2
V2 –> cAMP –> PKA –> AQ2
ADH stimulates phosphorylation of […] to apical membrane
AQ2
water enters cell –> more water in plasma
AQ2 allows water into the cells, increasing the concentration of water in the
serum or urine
serum
Anti-diuresis requires what two factors?
- ADH to increase renal tubular permeability
- a gradient that will favor water reabsorption
creates the gradient needed for ADH action later
loop of Henle
transporter that is always basolateral
NaKATPase
transporters in ascending loop of Henle
basolateral: NaKATPase
apical: NKCC
bring salt from tubule into interstitium
salt from the ascending loop of Henle will accumulate in the interstitium and then move into
descending loop of Henle
salt is slowly added to fluid as it moves through descending loop, water
water out
salt is slowly added to fluid as it moves through the […] loop of Henle
descending
salt in, water out
what part of the loop of Henle is impermeable to water?
ascending
osmolarity […] in the descending loop of Henle
increases
salt coming in, water going out
osmolarity […] in the ascending loop of Henle
decreases
salt out, water stays same
reduces the osmolarity of fluid in the tubule
what part of tubule
loop of Henle
creates gradient for reabsorption in collecting duct
unless ADH is present, the walls of the collecting duct are […] to water
impermeable
diluting segment of the loop of Henle
ascending
ADH […] the osmolarity of fluid in the collecting tubule
increases
water reabsorbed
how would the absence of ADH affect urine concentration?
low osmolarity
high volume
what part of the kidney has the highest salt concentration?
medulla
what structure protects the countercurrent mechansim and supplies nutrients to the cell?
vasa recta
the juxtaglomerular nephrons have longer loops of Henle and participate in
concentrating the urine
the nephrons in the cortex with very short loop of Henles are mainly for
filtration
why does blood flow through the vasa recta have to be slow?
when increased, more salt is reabsorbed from the interstitium which decreases the countercurrent effects
low protein diets decrease urea. How would that effect the countercurrent mechanism?
decreases countercurrent mechanism
high urea concentrations favor the countercurrent mech.
furosemide inhibits
NKCC
inhibit Na+ reabsorption, more urine production
acute ECF volume expansion trigger the release of
atrial natriuretic peptide
decreases renal tubular sodium and fluid reabsorption
atrial natriuretic peptide
released due to distension of the atria
atrial natriuretic peptide
after a prolonged period without water intake, ECF decreases and the […] is activated
sympathetic nervous system
alpha-1-adrenoreceptors
causes systemic vasoconstriction, including the glomerular afferent arteriole
alpha 1 adrenoreceptors
increases the permeability of distal and collecting tubules causing water to be reabsorbed
ADH
effectiveness of the countercurrent mechanism requires:
3
- ADH
- urea in the kidney medulla
- salt reabsorption in the loop of Henle
an increase in blood flow through the vasa recta will cause
salt in the renal medulla to be washed away
decrease effectiveness of countercurrent mech.
a decrease in salt delivery to the macula densa will trigger the release of
renin
aldosterone activates
2
NaKATPase
ENaC
activates NaKATPase at the basolateral membrane of the principal cells of the collecting tubules
aldosterone
a negative value for the UAG indicates
kidneys are producing and excreting NH4+
what conditions cause hyperkalemia?
shifting K out of cell
Digoxin
hyperOsmolarity
Lysis of cells
Acidosis
B-blockers
high blood Sugar (insulin deficiency)
Succinylcholine
DO LABSS
what conditions cause hypokalemia?
shifting K+ into cell
hypo osmolarity
alkalosis
B agonist
insulin
insulin shifts K+ INto cells
