Reading...
Play button
Play button
Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
60 Cards in this Set
- Front
- Back
|
Total urine excretion = filtered -reabsorbed + secreted
|
cool story
|
|
|
What happens to glucose and amino acids that are in the tubular fluid?
|
almost all are reabsorbed back into the blood
|
|
|
What happens to sodium and other electrolytes found in the urine?
|
mostly reabsorbed into blood
|
|
|
What happens to urea and other waste products found in the urine?
|
not reabsorbed; they need to stay in the urine and be excreted
|
|
|
What is the paracellular route of reabsorption?
|
water and some ions travel through the space between the cells out of the lumen
|
|
|
How does glucose get reabsorbed into the blood from the tubular fluid?
|
secondary active transport with Na+ (SGLT2/SGLT1 co-transporter)
|
|
|
What type of junctions are found between the cells of the proximal tubule?
|
tight junctions
|
|
|
Active transport requires what compound?
|
ATP
|
|
|
How does secondary active transport of glucose work to bring it back in the cell? describe the process
|
Na/K pump on the basolateral side of the proximal tubule epithelium pumping Na into the blood = low [Na] in the cell = sodium flows into the cells out of the tubular fluid using SGLT co transporter that also brings glucose in with it. Then GLUTs move glucose passively into the blood
|
|
|
What is the function of GLUT transporters?
|
allow glucose to move from in the proximal tubule cells into the interstitial fluid (and eventually blood)
|
|
|
How does the Na/K pump work?
|
pumps 3 sodium out of a cell, puts 2 K+ into a cell; uses ATP
|
|
|
How is hydrogen secreted into the proximal tubules?
|
secondary active transport; anti-port. Na/K pump creates low Na in cell = Na moves into cell = H+ moves out into the tubular fluid
|
|
|
How are amino acids reabsorbed?
|
secondary active transport; co-transport with Na into cell (Na/K pump creates gradient fro Na movement)
|
|
|
What is pinocytosis?
|
protein reabsorption in the brush border. vesicles are formed and ATP is needed
|
|
|
What is a transport maximum? Why does it happen?
|
the max rate of reabsorption of a certain ion in the kidney. occurs due to protein kinetics, only so many transporters can be active. diabetics may have glucose in the urine that exceeds this transport maximum and thats why it actually ends up in the collecting duct
|
|
|
Why is there no transport maximum for sodium?
|
it doesn't completely rely on protein carriers. some sodium it can diffuse, use the paracellular route, spends more time in the proximal tubule. exhibits gradient-time transport
|
|
|
What is gradient-time transport?
|
sodiums rate of transport (reabsorption) is depends on electrochemical gradient and time spent in the tubule
|
|
|
Even though sodium is actively transported, why does it still exhibit a gradient-time transport, rather than having a transport maximum?
|
the Na/K ATPase can pump sodium way faster than the co-transporter; some sodium leaks back into the tubular fluid
|
|
|
Slower moving tubular fluid has what effect on sodium reabsorption?
|
increase sodium reabsorption
|
|
|
What is solvent drag?
|
as more water moves back into the blood in the proximal tubule, some solutes get carried in with it (sodium)
|
|
|
How are Chloride and other solutes reabsorbed by passive diffusion?
|
paracellular pathway, solvent drag, transporters (urea)
|
|
|
In the late proximal tubule, once all the glucose and amino acids have been reabsorbed, what is co-transported with sodium?
|
Cl-
|
|
|
As tubular fluid flows through the proximal tubule, what happens to the [sodium]?
|
remains constant; sodium is reabsorbed, but water moves with it so the actual concentration is the same
|
|
|
As tubular fluid flows through the proximal tubule, what happens to the [urea]?
|
increases slightly; as water leaves the tubule
|
|
|
As tubular fluid flows through the proximal tubule, what happens to the [creatinine]?
|
increases as it is secreted into the tubular fluid
|
|
|
As tubular fluid flows through the proximal tubule, what happens to the [glucose/amino acid]?
|
drops off dramatically since it is all taken back into the blood
|
|
|
What happens in the descending loop of Henle?
|
a lot of water moves out of the tubular fluid = highly concentrated fluid
|
|
|
What happens in the ascending loop of Henle?
|
remaining ions leave the tubular fluid (Na/Cl/K transporter + Na/K pump); impermeable to water
|
|
|
How does Furosemide work as a diuretic?
|
blocks the reabsorption of Na, Cl and K by blocking that 1 transporter
|
|
|
Why id the distal tubule considered the "diluting" portion?
|
dilutes tubular fluid by reabsorbing most ions
|
|
|
How do thiazide diuretics work to increase urine volume?
|
block Na/Cl co-transport into the blood. more sodium stays in the tubular fluid, the water stays with it. the "diluting" function of the distal tubule cannot be done when thiazides are given
|
|
|
What do principal cells do in the distal tubule?
|
Pumps sodium back into the blood and K into the tubular fluid
|
|
|
How do spironolactone and amiloride work as diuretics?
|
block principal cells from taking sodium (and water with it) back into the blood. spironolactone is an aldosterone antagonist (competes for receptors). amiloride blocks the sodium channel directly
|
|
|
Why are spironolactone and amiloride potassium-sparing diuretics?
|
since they block principal cells, the block sodium reabsorption and also potassium excretion. so potassium stays in the blood. furosemide blocks potassium and sodium (and chloride) reabsorption so a lot of K is lost with furosemide
|
|
|
What do intercalated cells do in the distal tubule?
|
move Potassium out of the tubular lumen; secrete hydrogen into the tubular fluid
|
|
|
Where does ADH insert aquaporins?
|
late distal tubule/early collecting duct
|
|
|
ADH function
|
binds receptors > cAMP mechanism > protein kinase A activated > AQP-2 phosphorylated > AQP-2 inserts in membrane = water moves into the blood out of the urine
|
|
|
What does the ratio of inulin in urine vs. plasma indicate? Why?
|
urine:plasma inulin tells us water reabsorption rate. it is completely removed during filtration and not adjusted anywhere else in the nephron so it tells us GFR, but also lets us know where water is. Since the amount of inulin should stay constant in the tubular fluid, we know that if the [inulin] increases water left the tubular fluid. if [inulin] decreases it means water moved into the tubular fluid to dilute it
|
|
|
When BP is very high, what 2 regulatory mechanisms prevent GFR from increasing too high?
|
autoregulation and glomerulotubular balance
|
|
|
A high plasma colloid pressure has what effect on reabsorption?
|
increases reabsorption; water wants to dilute the plasma
|
|
|
A high capillary pressure has what effect on reabsorption?
|
decreases reabsorption; pushes water away from entering capillary
|
|
|
Increased BP in the afferent arteriole has what effect on reabsorption?
|
less absorption; more pressure in the peritubular capillary resists fluid moving into it
|
|
|
Increased resistance in the afferent arteriole has what effect on reabsorption?
|
increases reabsorption; the blockage in the afferent arteriole makes the distal peritubular capillaries lower hydrostatic pressure and that favors reabsorption
|
|
|
A higher filtration fraction has what effect on reabsorption?
|
increases reabsorption; high filtration fraction = higher GFR = more water leaves = high colloid osmotic concentration = more water reabsorption to try to dilute that
|
|
|
Even though there are tight junctions, why can some ions go back into the tubular fluid after they are reabsorbed?
|
because the tight junctions are actually leaky
|
|
|
As water is reabsorbed into the capillaries, what happens to interstitial fluid hydrostatic pressure?
|
decreases; water leaves the interstitial fluid
|
|
|
When BP is very high, why does pressure natriuresis/diuresis occur?
|
more sodium and water is forced into the tubular fluid from the glomerular capillaries; less reabsorption due to increased peritubular capillary pressure
|
|
|
Aldosterone works on which cells of the distal collecting duct?
|
principal cells
|
|
|
What is Addison's disease?
|
low Aldosterone
|
|
|
What is Conn's syndrome?
|
high aldosterone
|
|
|
Angiotensin 2 vasoconstricts and causes aldosterone release from adrenal cortex (glomerulosa). What is its 3rd function?
|
directly increase sodium reabsorption by stimulating the Na/K pumps
|
|
|
How does ANP work?
|
atrial natriuretic peptide inhibits sodium reabsorption, decreases renin
|
|
|
What does parathyroid hormone do?
|
increase blood calcium levels
|
|
|
Sympathetics have what effect on sodium reabsorption?
|
increase reabsorption; constriction in the arterioles = lower pressure distally in the peritubular capillaries = less hydrostatic pressure = more movement in
|
|
|
Why is creatinine clearance a good indicator of GFR?
|
all creatinine is typically excreted via glomerular filtration and only small amounts are secreted
|
|
|
PAH clearance is a good indicator of ...
|
renal blood flow
|
|
|
Inulin clearance is a good indicator of ...
|
GFR
|
|
|
Filtration fraction =
|
GFR/(total renal blood flow)
|
|
|
in terms of PAH: total plasma blood flow =
|
PAH clearance / (PAH excretion ratio); PAH excretion ratio= 5 of PAH removed from blood during glomerular filtration
|
|
|
Creatinine has a higher clearance rate than inulin, even though inulin is completely removed in the GFR. What does this tell us about creatinine excretion?
|
it is also secreted by the tubular fluids; theoretically, nothing should have a higher clearance rate than inulin unless it is also being added after the glomerular filtration
|
