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

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Flashcards in 05.06 - Proximal Tubule (Rao) - PP, LG, No reading, Not watched Deck (61):
1

Symptoms of Glucosuria

Thirst and Nocturia due to Osmotic Diuresis

2

Phosphate Reabsorption is coupled to what in PT

Na

3

What facilitates water reabsorption in PT

Leaky epithelium and High Hydraulic conductivity

4

Transporters for Mannitol

None

4

What drives active transport of Na in PT

Na-K ATPase

5

2 important luminal Na channels in PT

Na-H exchanger, Na-Glucose cotransporter

5

Protein excretion is high in what 3 conditions

MS, Hemoblobinemia, Myoglobinemia

6

VL =

(GFR x Pin) / Tfin

6

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

Na

6

Patient without Parathyroid will excrete ___ phosphate than normal

Less

7

Primary role of PT

Reabsorb most of the filtered water and solutes

7

How is phosphate reabsoprtion regulated

Hormones: PTH decrease Tm -> More secretion, excretion

8

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

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

9

How does inulin concentration change in tubular fluid of PT

Increases, no reabsorption

10

How is HCO3- pumped out to ISF in PT

HCO3/Na cotransporter

11

Anion transport in PT occurs predominantly by

Diffusion via paracellular route

12

Cl is passively reabsorbed in PT due to

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

13

What favors Anion transport via Paracellular Space

Leaky epithelium

14

Mutation in what causes Familial Renal Glucosuria

SGLT1/2

14

Filtration and Reabsorption of Mannitol

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

15

GFR x Pin =

VL x Tfin

15

When does Bicarb begin to be absorbed more rapidly

After transition from PCT to PST

17

What drives water reabsorption in PT? What facilitates this?

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

18

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

Increase osmolarity and cause diuresis

20

3 Causes of Glucosuria

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

21

Reabsorption of what ions follow Na to maintain electroneutrality

Chloride and Bicarb

22

Changes in Cl and Bicarb absorption from PCT to PST

Cl absorption reduced, Bicarb is absorbed more rapidly

23

Bicarb reabsorption requires

Active secretion of protons

25

What accounts for majority of O2 consumption by kidney

Sodium reabsorption

26

Result of Na-K ATPase activity

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

26

Which segments of nephron actively secrete H+ into lumen

PT, DT, and CD

26

Poorly permeant solutes can serve as

Diuretics

28

Glucose reabsorption across apical membrane is coupled to

Na

30

How does Glucose cross apical membrane

Sodium-Glucose Cotransport: SGLT1/2

31

What percent of Bicarb is reabsorbed in PT

95%

32

Threshold for Phosphate Reabsorption

Low, regulated by plamsa concentration and hormones

34

How does PAH concentration change in tubular fluid thru PT

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

35

How is urea reabsorbed in PT

Passively, but slow: only 50%

36

Effect of Mannitol infusion

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

37

How does Bicarb concentration change in tubular fluid thru PT?

Decreases, high reabsorption

38

Where are Na-K pumps exclusively localized?

Basolateral membrane

39

Entire plasma volume is filtered __ times thru glomerulus each day

60 times (5 times for whole body fluid)

39

How does change in UF affect Urea clearance

Increase in UF increases Urea clearance

41

How does Inulin concentration change with distance from Glomerulus

Increases

43

Leaky epithelium of PT favors

Anion transport via Paracellular Space

44

What drives Cl transport in PT

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

45

AA absorption across luminal membrane is coupled to

Na gradient

46

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

60%, due to active transport of HCO3

47

Chloride, K, and Urea are reabsorbed by

Passive transport

49

How do Organic Acids cross luminal membrane

Co transport with Na

51

Major solutes that contribute to isotonic reabsorption in PT

Sodium, Chloride, Bicarb

52

How do AA's cross luminal membrane

Na-AA cotransport

53

How does Cl concentration change in tubular fluid thru PT

Slight increase due to Bicarb reabsorption

54

What proportion of Glucose is reabsorbed in PT

All, until reaches threshold

55

In PT, H+ secretion is mediated by

Apical Na-H exchanger (driven by Na gradient)

56

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

Cl-, H+ secretion

57

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

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

58

What percent of AA's are reabsorbed in PT

98-99.5

59

GFR - Reabsorption [+ Secretion] =

Rate of flow into loop of Henle

60

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

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

61

How is Na absorbed from tubular lumen in PT

Passively down apical membrane sodium channel