III: Tubular Transport II Flashcards

1
Q

Histology of thin descending and ascending limb membrane

A

Epithelial membrane without brush border + LOW metabolic activity

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2
Q

Histology of thick ascending limb membrane

A

Thick epithelial membrane + HIGH metabolic activity

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3
Q

In pictures, differentiate between thin and thick limb of loop of henle

A

Thin descending loop of henle looks round with 2/3 round cells

Thick ascending loop of henle looks round with MANY round cells

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4
Q

Thin descending limb contains in both membranes

A

AQP1

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5
Q

In thin descending limb what is reabsorbed

A

High H2O and low solute reabsorption

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6
Q

There is an increase osmolarity in

A

Tubular lumen

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7
Q

How much H2O is reabsorbed in the loop of henle

A

20%

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8
Q

Thin ascending limb is permeable/nonpermeable to water

A

Impermeable

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9
Q

Where does reabsorption of Cl- begin

A

At thin ascending limb

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10
Q

Reabsorption of Cl- in ascending limb through

A

Transcellular pathway (CLC-K1)

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11
Q

Na+ reabsorption is through

A

Paracellular pathway

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12
Q

In thick ascending limb, what is reabsorbed

A

Solutes and not water

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13
Q

How much filtered Na+ and Cl- does the THICK ascending limb reabsorb

A

25%

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14
Q

K+, Cl- and Ca++ also reabsorbed in the

A

Thick ascending limb

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15
Q

Descending and ascending limb permeability

A

Descending is permeable
Ascending is impermeable

Descending reabsorbs water
Ascending reabsorbs solutes

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16
Q

What is reabsorbed in thick ascending limb

A

Na+, K+, Cl-, HCO3-, Mg+

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17
Q

Channels involved in Thick ascending limb (reabsorption of Na+, Cl-, K+, Mg++, Ca++, HCO3-)

A
NHE3 (H+, Na+)
AQP
NKCC2 (Na+, 2Cl-, K+)
ROMK (K+)
Na+/K+ATPase

Direct ones for K+ and Cl-

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18
Q

Why is there a decrease in tubular osmolarity in thick ascending limb

A

Because no H2O is reabsorbed

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19
Q

Distal convoluted tubule sections

A
Initial portion
Distal portion (connecting tubule)
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20
Q

Collecting tubule sections

A

Cortical

Medullary

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21
Q

Initial part of distal convoluted tubule called the

A

Cortical diluting segment

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22
Q

Initial part of distal convoluted tubule reabsorbs (Na+, Cl-) %

A

5%

23
Q

What is not reabsorbed in INITIAL part of distal convoluted tubule

A

Water or urea

24
Q

If not water or urea is reabsorbed in INITIAL part of distal convoluted tubule then (osmolarity)

A

Low tubular osmolarity

25
Q

Channels involved in INITIAL portion of distal convoluted tubule

A

NCC (Cl-, Na+)
Na+/K+ATPase

Paracellular transport of Ca++, Mg++, Na+, Ka+
Transcellular transport of Cl- and K+

26
Q

There is paracellular transport of

A

Mg++, Ca++,

27
Q

There is transcellular transport of

A

Cl-

28
Q

Location of connecting tubules (cortex and medulla)

A

Begin at cortex but most are at medulla

29
Q

Cells involved in connecting tubules

A

ADH

Aldosterone

30
Q

Function of ADH

A

Reabsorb water

31
Q

Function of aldosterone

A

Reabsorb Na+ and secrete K+

32
Q

Intercalated cells at CONNECTING TUBULES function

A

Regulate acid-base balance

33
Q

H+ secretion in intercalated cells. Which cells does this

A

Type A cells

34
Q

HCO3- secretion in intercalated cells. Which cell does this?

A

Type B cell

35
Q

How much Na+ is reabsorbed in distal tubule + collecting tubules

A

3%

36
Q

Why is there only a 3% reabsorbtion of Na+ in distal tubule and collecting ducts

A

Because it is hormone regulated

37
Q

Inhibitor channels

A

Amiloride triamterene

Sironolactone

38
Q

Inhibition of amiloride triamterene

A

Blocks Ca++ channels

Inhibit ENaC therefore inhibit aldosterone induced increase in Na+ reabsorption

39
Q

Which channel is blocked through amiloride triamterene

A

ENaC

40
Q

Inhibition of Spironolactone

A

Aldosterone antagonist. Prevents aldosterone from entering nucleus = blocks mRNA synthesis

41
Q

Aquaporins depend on…

A

ADH

42
Q

Why do aquaporins depend on ADH

A

Because ADH stimulates water absorption

43
Q

What would happen if there was no ADH

A

There will be no water permeability

44
Q

ADH causes

A

Increased osmolarity
ADH release
Water permeability

45
Q

In diabetes insipidus there is no

A

ADH

46
Q

In SIADH there is

A

High ASDH

47
Q

Intercalated cells regulate

A

Acid-base homeostasis

48
Q

Type A cells in intercalated cells in charge of

A

Acidosis
Secrete H+
Reabsorb HCO3-
Reabsorb K+

49
Q

Type B cells in intercalated cells in charge of

A

Alkalosis
Secrete HCO3-
Secrete K+
Reabsorb H+

50
Q

Collecting tubule at medullary segment, H2O reabsorption

A

Adjusted due to permeability controlled by ADH

51
Q

Collecting tubule at medullary segment permeability to urea

A

Permeable

52
Q

What does the collecting tubule at medullary segment secrete

A

H+

53
Q

What % of Na+ is finally reabsorbed in collecting tubule of medullary segment

A

<1%Na+