True/False: reabsorbed compounds do not usually get secreted back into the tubuleTrue False
True
How to calculate reabsorption?
Reabsorption = filtration – excretion Difference between filtration and excretion
What does it mean when excretion is less than filtration?
It means things got reabsorbed
What is the equation to calculate for filtered substance
Filtered (s)= GFR x Plasma concentration of substance (Ps)
What is the equation to calculate excreted substance?
Excreted (s) = Urine concentration of S (Us) x Urine flow rate (V)
Which equation uses urine concentration and urine flow rate to calculate?
Excretion of substance S
Which equation involves GFR and plasma concentration of s?
Filtration of S
What results in taking the difference between filtration and excretion?
Reabsorption
What results in taking the difference between excretion and filtration?
Secretion
How is secretion calculated?
Secretion = excretion – filtration
What does it mean when excretion is greater than filtration?
It means things got secreted
True/false: when filtration is greater than excretion, net secretion is 0True False
True
Reabsorption occurs when excretion is _____ than filtration
Less
Secretion occurs when excretion is _____ than filtration
Greater
True/false: tubular reabsorption requires passive and active mechanismsTrue False
True
Tubular cells’ Basolateral membrane is on the _____ side
Blood
Tubular cells’ Luminal (apical) membrane is on the ____ side
Tubular lumen
Brush border is on the ____side of tubular cells
Luminal
True/false: glucose will be excreted when there is high plasma glucose (after reaching threshold)True False
True
True/false: reabsorption of glucose stops after reaching transport maximum pointTrue False
True
True/false: filtered load of glucose increases linearly with plasma glucose concentrationTrue False
True
Reabsorbed glucose is the same as which other number?
T max
How to calculate excretion of glucose?
Excretion glucose = filtration – reabsorption With filtration = GFR x Plasma [glucose]
Most sodium is absorbed in which part of the tubule?
65% of sodium is absorbed in the proximal tubule
How much sodium is excreted in a day?
True/false: typically, 90% of filtered water is reabsorbedTrue False
True
Which part of the nephron is also known as the diluting segment? Why?
Thick ascending loop Water is staying in the tubule
True/false: in dehydrated state, water can be reabsorbed 100%True False
True
Diuretic has what effect on urine output?
Increases
Proximal tubule is mostly associated with reabsorption of which substances?
Water is impermeable in which segments?
Ascending loop Early Distal tubule
NaCl reabsorption that is drive by Cl- gradient occurs in which segment?
Late proximal tubule
Na-glucose, Na-amino acid, Na-phosphate cotransporters and Na-H exchange are cellular mechanism in the ________ tubule
Early proximal
Which hormones act on early proximal tubule?
PTH inhibits Na+-phosphate cotransport Angiotensin II stimulate Na-H exchange
Na+-phosphate cotransport is inhibited by ______ in the_______ tubule
Na+-H+ exchange is stimulated by ______ in the _____ tubule.
Angiotensin II Early proximal
True/false: angiotensin II increases blood pressure, so it stimulates the Na+-H+ exchange in order to reabsorb more sodium back into the bodyTrue False
True. Since water follows sodium, this would allow for more blood volume
True/False: ascending loop of henle don’t have brush border on cell surfaceTrue False
False; ascending loop has brush border on surface, it is the descending loop that don’t have brush border cells
True/False: descending loop of henle allows lots of water to be reabsorbedTrue False
True
______ loop of henle has large lumen without brush border surface
Descending
True/false: Hypoosmotic reabsorption means no water is taken back, just the solutes and this occurs in the descending loop of henleTrue False
False; all is true except the part of descending loop, it’s the ascending loop that is hypoosmotic, impermeable to water
What are some cellular mechanisms found in the thick ascending loop?
Na+-K+-2Cl- cotransport Na+-H+ exchange
Reabsorption of Ca2+ and Mg2+ driven by the lumen-positive potential occurs in which segment?
Thick ascending loop
Which hormone stimulates Na+-K+-2Cl- cotransport in thick ascending loop?
ADH
True/false: early distal tubule is not permeable to water and ureaTrue False
True
Where are macula densa located?
Early distal tubules
Low NaCl has what effect on GFR?
Increases
High NaCl would have what effect on GFR?
Decrease
What cellular mechanism is found in early distal tubule?
Na+-Cl- cotransport
True/false: early distal tubule’s permeability to water depends on ADHTrue False
False; early distal tubule is NOT permeable to water. It is LATE distal tubule/collecting duct’s water permeability depends on ADH
What are major function of principal cells in late distal tiubule and collecting duct?
Reabsorption of NaCl K+ secretion Variable water reabsorption depending on ADH
Which hormone stimulates Na+ reabsorption in late distal tubule / collecting duct?
Aldosterone
Which hormone stimulates K+ and H+ secretion in late distal tubule/ collecting duct?
Aldosterone
Which hormone stimulate water reabsorption in late distal tubule/ collecting duct?
ADH
What are the major functions for alpha intercalated cells in late distal tubule/ collecting duct?
Reabsorption of K+ Secretion of H+
True/false: there are no major diuretics acting on glomerulus, proximal tubulesTrue False
True
Osmotic agents act on _____ and Loop diuretics acts on _____ .
Thin descending loop Thick ascending loop
Thiazide acts on ______
Distal convoluted tubule
True/false: if water is reabsorbed to a greater extend than the solute, the solute will become less concentrated in the tubuleTrue False
False; the solutes will become more concentrated since there is more water leaving the tubules and getting reabsorbed
True/false: if water is reabsorbed to a lesser extent than the solute, the solute will become less concentrated in the tubuleTrue False
True
Creatinine and inulin are _____ concentrated in tubule because they _____.
More Do not get reabsorbed
Glucose and amino acids are _____ concentrated in tubule than water because they _____.
True/false: natriuretic peptides are releades in hypervolemia stateTrue False
True
Natriuretic peptides and prostaglandins ______ GFR, while adenosine ____ GFR
What is renal clearance?
Rate of removing a substance Volume of plasma completely cleared of that substance per minute
What is the equation used to calculate renal clearance?
C= U x V / P U= urine concentration of S V= urine flow rate P= plasma concentration of S
What does it mean when a clearance of a substance is high?
Means the body wants to get rid of it bad
True/false: for a substance that is freely filtered and not reabsorbed or secreted (ie like inulin, creatinine), renal clearance is equal to GFRTrue False
True
True/false: if a substance is completely cleared from the plasma, the clearance rate should theoretically be equal to renal plasma flowTrue False
True
In substance like inulin, amount filtered is the same as amount _______.
Excreted
If the ratio of a substance to inulin is <1, this means that the compound is_______ by the body
Reabsorbed
If the ratio of a substance to inulin is >1, this means that the compound is __________
Filtered and secreted
True/false: Water has a C water /C inulin ratio of less than 1, this means that water is reabsorbed by the bodyTrue False
True
PAH has a Cx/C inulin ratio of _____? Which means what?
Greater than 1 Means it is filtered and secreted
What is the relationship between GFR and plasma creatinine concentration?
As GFR increases, plasma concentration of creatinine decreases
True/false: para-aminohippuric acid (PAH) clearance estimates renal plasma flow (ERPF)True False
True
What is ERPF?
Estimated renal plasma flow, underestimates RPF by 10% Is when a substance like PAH that is freely filtered and secreted and almost completely cleared from the renal plasma, the ERPF would equal to clearance
What is the equation for renal blood flow (RBF)?
RBF= RPF/ 1-Hct
