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63 Cards in this Set
- Front
- Back
Reabsorption = Filtration - what
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Excretion
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Filtration of x = GFR * what
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plasma concentration of x
[x] |
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excretion of x = urine flow (V) * what
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urine concentration of x
[x] |
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Secretion = Excretion - what
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Filtration
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If you have a negative Reabsorption, then you have no ___ reabsorption,
but you do have ____ secretion |
net
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Glomerular filtration is largely ___-selective.
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non
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Tubular reabsorption is highly _____
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selective
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How do you tell proximal tubule from distal tubule?
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microvilli
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Tubular cells use a ___-port pump for glucose and Na
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sym
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Tubular cells use a ___-port pump for H+ and Na
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anti
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Creatinine is permeable or impermeable to the tubular membrane
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impermeable
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chloride is transported across the luminal membrane with sodium by _______active transport
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secondary
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Sodium travels in Both trans and paracellular routes with membrane potential of about ______mV.
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-70mV
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There are sodium carriers on luminal surfaces in ____ border
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brush
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Water moves into peritubular capillaries via _____ filtration (bulk flow).
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ultra
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Tubular cells use a ___-port pump for amino acids and Na
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sym
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Large proteins are absorbed in the proximal tubule via __________.
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pinocytosis
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the tubular load at which transprot maximum is exceeded in some nephrons.
This is not exactly the same as the transport max of the whole kidney b/c some nephrons have lower transport max's than others. |
Threshold
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A uninephroectomized pt with uncontrolled DM has a GFR of 90ml/min, a plasm glu of 200 mg/dl (2mg/ml), and a transport max of 150 mg/min. What is the glucose excretion for this pt?
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30 mg/min
Filt of glu = GFR * plasma conc of glu Excr = Filt - reabsorp Excr = Filt - transport max |
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Where does most reabsorption occur?
What is exception? |
Proximal tubule
Exception: Mg ion is reabsorbed in thick ascending loop of Henle |
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Where does most secretion occur?
What is exception? |
proximal tubule
exception: K+ is secreted in late distal tubule by principal cells |
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H+ ion is secreted. What is reabsorbed as a result?
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H2O and CO2
(b/c H+ is buffered by bicarbonate, and carbonic acid is split to CO2 and H2O by carbonic anhydrase) |
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Why is phosphate a good intracellular buffer but a poor blood buffer?
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?
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As fluid moves thru proximal tubule, what things decrease in concentration?
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Amino Acids
Glucose HCO3 |
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As fluid moves thru proximal tubule, what things increase in concentration
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Creatinine
Urea Chloride- |
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Whys does Na+ concentration remain constant?
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b/c osmolality remains constant
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PAH is used to measure ____ flow
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RPF
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Loop of Henle – Water and sodium reabsorption though _______ exchange.
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countercurrent
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Descending thin limb is highly permeable to water and moderately permeable to urea and ____
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sodium
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Thin ascending limb is impermeable to water and has some permeability to Ca++, bicarbonate and ________. Permeable to Na++
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magnesium
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Thick limb is highly metabolic with active reabsorption of _____(3) through secondary active transport.
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sodium, potassium and chloride
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Thick limb:
Also Ca++ Mg++ and bicarbonate are highly reabsorbed here. Impermeable to _____ |
water
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20% of filtered water is reabsorbed in the loop of Henle mainly in the ______ limb
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descending
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25% of filtered Na+, K+ and CI- is reabsorbed in the loop of Henle mainly in the _______ thick limb.
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ascending
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What is "The diluting segment"?
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Early distal tubule
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thiazides inhibit the Na/Cl symport where?
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early distal tubule
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Maximal urine concentration
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1200-1400 mOsm / L
sp gr ~ 1.030 |
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Minimal urine concentration
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50-70 mOsm / L
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the countercurrent multiplier region of the kidney
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medulla
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Glomerular filtrate is isotonic.
Pre-urine passing through the proximal tubule remains isotonic. Why? |
?
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What is the urine osmolarity in the three parts of the loop of Henle?
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Descending thin limb- the fluid becomes more hypertonic
Ascending thick limb- the fluid becomes more hypotonic… Why? |
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b. Active transport of ions takes place in the ascending thick limb. This transport is a unique symport system and is a necessary component in maintaining the __________ multiplier
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countercurrent
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the thick ascending limb is sometimes referred to as a “diluting segment” because of the removal of solute. This label is however is more classically applied to the ________.
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early distal tubule
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There is an obligatory urine volume.
For 70kg human: ____mOsm of solute/ day must be excreted to maintain electrolyte balance |
600mOsm
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There is an obligatory urine volume.
If the max urine osmolarity is 1200 mOsm/l and 600 mOm/day must be excreted (for a 70kg human), what is urine volume per day? |
0.5 L/day
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Countercurrent multiplication
1. Requires the special arrangement of loop of Henle and vasa _____ |
recta
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Countercurrent multiplication
2. Requires active transport of Na+ and co-transport of K+ and C1- in __________ limb. |
thick ascendingCountercurrent multiplication
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Countercurrent multiplication
3. Requires active transport of ions from the collecting ducts into the |
interstitium
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Countercurrent multiplication
4. Requires the movement of urea from the medullary collecting duct into the interstitum by bulk flow (in the presence of _____). |
ADH
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6. What are the tubular characteristics of the loop of Henle relative to urea? What is the importance of this characteristic?
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virtually impermeable to urea
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Urea is passively reabsorbed in the __________
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proximal tubule
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In the presence of ADH, water is reabsorbed in distal and collecting tubules, concentrating ____ in these parts of the nephron
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urea
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The inner medullary collecting tubule is highly permeable to urea, which diffuses into the medullary _______
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interstitium
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ADH increases urea permeability of medullary ___________ tubule.
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collecting tubule
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Vasa recta blood flow is low (only ___ % of total renal blood flow)
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1-2
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Early Distal Tubule:
-Functionally similar to thick ascending loop -Not permeable to _____ (called diluting segment) Active reabsorption of Na+, Cl-, K+, Mg++ Contains macula densa |
water
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Early Distal Tubule:
-Active reabsorption of ____(4 ions) -Contains macula densa |
Na+, Cl-, K+, Mg++
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Na channel blockers that inhibit Na reabsorption in collecting tubule by blocking Na channels in the lumen side of Principal cells
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Amiloride
Triamterene |
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Aldosterone blockers that inhibit Na reabsorption in collecting tubule
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Spironolactone
Eplerenone |
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Intercalated cells reabsorb ___ and secrete H+.
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K+
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Principal cells reabsorb Na+ and water and secrete ___.
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K+
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ADH regulates water permeability. Aldosterone regulates Na+ reaborption and ___ secretion.
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K+
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What is meant by potassium-sparing and how are sodium channel blocking and aldosterone antagonist type diuretics involved?
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?
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