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Renal > 05.06 - Proximal Tubule (Rao) - PP, LG, No reading, Not watched > Flashcards

05.06 - Proximal Tubule (Rao) - PP, LG, No reading, Not watched Flashcards

1
Q

Symptoms of Glucosuria

A

Thirst and Nocturia due to Osmotic Diuresis

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2
Q

Phosphate Reabsorption is coupled to what in PT

A

Na

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3
Q

What facilitates water reabsorption in PT

A

Leaky epithelium and High Hydraulic conductivity

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4
Q

Transporters for Mannitol

A

None

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4
Q

What drives active transport of Na in PT

A

Na-K ATPase

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5
Q

2 important luminal Na channels in PT

A

Na-H exchanger, Na-Glucose cotransporter

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5
Q

Protein excretion is high in what 3 conditions

A

MS, Hemoblobinemia, Myoglobinemia

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6
Q

VL =

A

(GFR x Pin) / Tfin

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6
Q

Only quantitatively important substance whose transport is directly coupled to metabolic energy in PT

A

Na

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6
Q

Patient without Parathyroid will excrete ___ phosphate than normal

A

Less

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7
Q

Primary role of PT

A

Reabsorb most of the filtered water and solutes

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7
Q

How is phosphate reabsoprtion regulated

A

Hormones: PTH decrease Tm -> More secretion, excretion

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8
Q

How is the Na-K ATPase the driving force for Na absorption

A

(1) Decrease in intracellular Na; (2) Decrease in membrane potential

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9
Q

How does inulin concentration change in tubular fluid of PT

A

Increases, no reabsorption

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10
Q

How is HCO3- pumped out to ISF in PT

A

HCO3/Na cotransporter

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11
Q

Anion transport in PT occurs predominantly by

A

Diffusion via paracellular route

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12
Q

Cl is passively reabsorbed in PT due to

A

Concentration gradient created by water reabsorption; Electrochemical gradient created by Na reabsorption

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13
Q

What favors Anion transport via Paracellular Space

A

Leaky epithelium

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14
Q

Mutation in what causes Familial Renal Glucosuria

A

SGLT1/2

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14
Q

Filtration and Reabsorption of Mannitol

A

Freely filtered, but not reabsorbed -> Reduces water reasbsorption and increases excretion

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15
Q

GFR x Pin =

A

VL x Tfin

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15
Q

When does Bicarb begin to be absorbed more rapidly

A

After transition from PCT to PST

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17
Q

What drives water reabsorption in PT? What facilitates this?

A

Osmotic gradient facilitated by leaky epithelium with high hydraulic conductivity (high Kf)

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18
Q

Substances that are freely filtered, but not reabsorbed, can increase ___ and cause ___

A

Increase osmolarity and cause diuresis

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20
Q

3 Causes of Glucosuria

A

(1) Pregnancy; (2) DM; (3) Familial Renal Glucosuria (SGLT mut)

21
Q

Reabsorption of what ions follow Na to maintain electroneutrality

A

Chloride and Bicarb

22
Q

Changes in Cl and Bicarb absorption from PCT to PST

A

Cl absorption reduced, Bicarb is absorbed more rapidly

23
Q

Bicarb reabsorption requires

A

Active secretion of protons

25
Q

What accounts for majority of O2 consumption by kidney

A

Sodium reabsorption

26
Q

Result of Na-K ATPase activity

A

Driving force for Na absorption (Decrease in intracellular [Na], Decrease in membrane potential)

26
Q

Which segments of nephron actively secrete H+ into lumen

A

PT, DT, and CD

26
Q

Poorly permeant solutes can serve as

A

Diuretics

28
Q

Glucose reabsorption across apical membrane is coupled to

A

Na

30
Q

How does Glucose cross apical membrane

A

Sodium-Glucose Cotransport: SGLT1/2

31
Q

What percent of Bicarb is reabsorbed in PT

A

95%

32
Q

Threshold for Phosphate Reabsorption

A

Low, regulated by plamsa concentration and hormones

34
Q

How does PAH concentration change in tubular fluid thru PT

A

Increases more than Inulin b/c not reabsorbed and actively secreted

35
Q

How is urea reabsorbed in PT

A

Passively, but slow: only 50%

36
Q

Effect of Mannitol infusion

A

Increases osmolarity -> Filtered -> Reduces water reabsorption and increases excretion

37
Q

How does Bicarb concentration change in tubular fluid thru PT?

A

Decreases, high reabsorption

38
Q

Where are Na-K pumps exclusively localized?

A

Basolateral membrane

39
Q

Entire plasma volume is filtered __ times thru glomerulus each day

A

60 times (5 times for whole body fluid)

39
Q

How does change in UF affect Urea clearance

A

Increase in UF increases Urea clearance

41
Q

How does Inulin concentration change with distance from Glomerulus

A

Increases

43
Q

Leaky epithelium of PT favors

A

Anion transport via Paracellular Space

44
Q

What drives Cl transport in PT

A

Due to rapid Na absorption, luminal fluid in PT is 5mV more negative than interstitial fluid

45
Q

AA absorption across luminal membrane is coupled to

A

Na gradient

46
Q

While 66% of fluid is reabsorbed in PT, only ___% of Cl is reabsorbed due to ___

A

60%, due to active transport of HCO3

47
Q

Chloride, K, and Urea are reabsorbed by

A

Passive transport

49
Q

How do Organic Acids cross luminal membrane

A

Co transport with Na

51
Q

Major solutes that contribute to isotonic reabsorption in PT

A

Sodium, Chloride, Bicarb

52
Q

How do AA’s cross luminal membrane

A

Na-AA cotransport

53
Q

How does Cl concentration change in tubular fluid thru PT

A

Slight increase due to Bicarb reabsorption

54
Q

What proportion of Glucose is reabsorbed in PT

A

All, until reaches threshold

55
Q

In PT, H+ secretion is mediated by

A

Apical Na-H exchanger (driven by Na gradient)

56
Q

HCO3- reabsorption is preferred over __, and driven by ___

A

Cl-, H+ secretion

57
Q

How does massive solute reabsorption affect osmolarity of tubular luminal fluid and interstitial fluid

A

Slight decrease in osmolarity of tubular luminal fluid and increase in interstitial fluid

58
Q

What percent of AA’s are reabsorbed in PT

A

98-99.5

59
Q

GFR - Reabsorption [+ Secretion] =

A

Rate of flow into loop of Henle

60
Q

Rank in order of most absorbed in PT: Bicarb, Inulin, AA’s, Glucose, PAH, Cl

A

Glucose, AA’s, Bicarb, Cl-, Inulin, PAH

61
Q

How is Na absorbed from tubular lumen in PT

A

Passively down apical membrane sodium channel

Renal (31 decks)

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