Tubular Reabsorption/secretion Flashcards

1
Q

Where is the Na+/K ATPase located in the tubular Epithelial cell?

A

Basolateral membrane

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2
Q

Where is water primarily reabsorbed?

A

Descending LOH

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3
Q

What ion is used to drive absorption of many solutes such as glucose, amino acids, and phosphates?

A

Na+

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4
Q

What is solvent drags?

A

Some solutes such as K+ and Ca++ are entrained in water as it is absorbed paracellularly

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5
Q

Where does reabsorption of HCO3 and secretion of H+ take place?

A

Proximal tubule

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6
Q

Describe the role of Carbanic anhydrase in glaucoma. What is a potential adverse affec?

A
  • Treaments for glaucoma include Carbanic anhydrase inhibitors as it inhibits production of the aqueous hum our
  • Can induce Acidosis
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7
Q

Describe Falconi Syndrome

A

Impaired absorption in proximal tubule leading to eastern of water, glucose, AAs, bicarbonate, etc in urine

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8
Q

How much of substances get absorbed in the PCT?

A

100% glucose/AA

80% HCO3

60-70% Na, K, Ca, Cl

60-70% Filtered Water

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9
Q

Describe the osmolality and change in volume in the PCT upon reabsorption

A
  • Isosmotic

- Volume reduced by 2/3

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10
Q

Describe the permeability in the descending loop of Henle.

A
  1. High H20 Perm
  2. Low Ion perm
  3. No evidence of active transport
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11
Q

Describe permeability in Ascending LOH.

A
  1. Low after Perm

2. Active transport of Na/Cl and other ions

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12
Q

How does osmotic concentration change along the loop of Henle?

A

Filtrate entering descending limb —> Isotonic

Filtrate entering ascending limb is Hyper osmotic

Filtrate exiting the ascending limb is hypoosmotic

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13
Q

What generates positive intraluminal charge of the ascending limb? What does the intraluminal charge drive?

A

Na/K/Cl Transporter generates intraluminal charge due to K+ backleak nto lumen via channels on apical membrane

Drives reabsorption of calcium

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14
Q

What percentage of Water and Ions is reabsorbed in the loop of Henle?

A

water - 15%

Ions - 25%

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15
Q

What are the three types of diuretics which work on the kidney?

A
  1. Loop diuretics (Na/K/CL transporter)
  2. Thiazides (Distal tubule NaCl blockers)
  3. K+ Sparing (Collecting Duct)
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16
Q

How do all diuretics wrk?

A
  • Elevate solute concentration of filtrate
  • Tubular lumen water retention from hydration of solutes
  • Increased excretion rate
17
Q

What is the major side affect of furosemide a loop diuretic? Why?

A

Hyopkalemia

Potassium has other channels into tubular lumen. —
> Excretion of Calcium

18
Q

What drives paracellular transport of Mg+ into the kidney interstitium?

A

Positive intracellular potential created by potassium

19
Q

What is Bartter Syndrome?

A
  • Mutation of Na/Cl/K transporter
  • Symptoms similar to loop diuretics
  • Polyuria
  • Hypokalemia
  • Hypercalceuria
  • Hypermagnesurea
20
Q

Describe the function of Thiazides diuretics

A

Block Na/Cl transporter in early distal tubule

21
Q

Differentiate Thiazides and loop diuretics.

A

Loop:

  • Na/K/Cl transporter
  • Hypokalemia
  • Hypercalceuria
  • Hypermagnesurea

Thiazides:

  • Na/Cl transporter
  • Hypokalemia
  • ***Hypocalciuria -> Thiazides increase calcium reabsorption
22
Q

What does Gitelman syndrome mimic?

A

Thiazides diuretics

23
Q

What is Fanconi syndrome?

A

Deficient glucose reabsorption

24
Q

Why are diabetics frequently urinating and always thirsty?

A

Glucosuria —> Water reabsorption In tubule

25
Q

How can sugars be used clinically as osmotic diuretics?

A

Exogenous sugars are used to promoters urinary loss of water in patients with cerebral edema and hyper hydration

26
Q

What are the two major cells in the distal nephron and their functions?

A

Principal Cells: Na reabsorption and K+ Secretion

Intercalated Cells: H+ secretion and K+ reabsorption

27
Q

How does aldosterone work on the distal nephron?

A

Stimulates Principal cell Na/K ATPase to promotes Na+ reabsorption and K+ secretion

28
Q

How does ADH work on the distal Nephron?

A

Loosens Tight barriers to allow water to leak into interstitium