Urinary 2 - Renal reabsorption Flashcards Preview

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Flashcards in Urinary 2 - Renal reabsorption Deck (44)
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1
Q

Where does the majority of reabsorption occur?

A

Proximal Convoluted Tubule

2
Q

Where does 65% H2O reabsorption occur?

A

PCT

3
Q

Where does 100% Glucose and amino acid reabsorption occur?

A

PCT

4
Q

What channel in the basolateral membrane drives renal reabsorption?

A

Na+/K+-ATPase

5
Q

Name the 2 Na+ channels located on the apical membrane of the PCT:

A

1 - Na+-Glucose symporter (SGLUT)

2 - Na+/H+ antiporter

6
Q

Name the Na+ channel located on the apical membrane of the TAL (LoH):

A

Na+/K+/2Cl symporter (NKCC2)

7
Q

Name the Na+ channel located on the apical membrane of the early Distal Tubule:

A

Na+/Cl- symporter (NCC)

8
Q

Name the Na+ channel located on the apical membrane of the late distal tubule and collecting ducts:

A

ENaC

9
Q

What substances are secreted into the tubules?

A
  • K+
  • H+
  • Organic anions and cations
10
Q

How do anions and cations move across the apical membrane (to be secreted)?

A

via H+ antiporter

11
Q

Name a few endogenous cations that are secreted into the tubule:

A
  • Acetylcholine
  • Dopamine
  • Adrenaline
  • Histamine
  • Serotonin
12
Q

Name a few drugs that are secreted into the tubule:

A
  • Sulfonamines
  • Morphine
  • Atropine
  • Isoproterenol
  • Penicillin
  • Salicylate
  • NSAIDs
13
Q

Name a few endogenous anions that are secreted into the tubule:

A
  • Urate
  • Bile salts
  • Fatty acids
14
Q

How are the majority of Cl- reabsorbed in the PCT?

A

via passive paracellular movement in S2/3 segment, down concentration gradient (no Cl- reabsorption in S1 segment)

15
Q

In which part of the tubule does 67% of Na+ reabsorption occur?

A

PCT

16
Q

Name the 3 driving forces for reabsorption from the PCT into the peritubular capillaries:

A

1) Osmotic gradient
2) Oncotic force (higher in peritubular capillary due to lack of protein in tubule)
3) Hydrostatic pressure (higher in interstitium, pushes solute into capillary)

17
Q

What is the name of the structure which invaginates the glomerulus?

A

Bowman’s Capsule

18
Q

Name the 2 types of nephrons:

A

1) Juxtamedullary

2) Cortical

19
Q

What type of nephron is most common?

A

Cortical (80%)

20
Q

How is the histology of the thin ascending LoH different to the PCT, and why?

A
In thin ascending LoH:
- no brush border
- no mitochondria
- wider lumen
No active transport in thin ascending LoH (^active transport in PCT)
21
Q

Name the main ions reabsorbed in the distal tubule:

A

Na+
Ca2+
Cl-

22
Q

What is reabsorbed in the descending LoH?

A

Only H2O

23
Q

In what part of the ascending LoH does active transport occur?

A

Thick ascending limb (TAL)

24
Q

What part of the nephron uses most energy, therefore is most susceptible to hypoxia?

A

Thick ascending limb of LoH (TAL)

25
Q

Name the channels in the basolateral membrane of TAL (Thick ascending limb of the LoH):

A

Cl- channel
Na+/K+-ATPase
K+/Cl- cotransporter

26
Q

Name the channels on the apical membrane of TAL (Thick ascending limb of the LoH):

A

Na+/K+/2Cl symporter (NKCC2)

ROMK

27
Q

What is ROMK, and in what part of the tubule is it present?

A

Renal Outer Medullary K+ channel

TAL (Thick ascending limb of LoH)

28
Q

What percentage of Na+ is reabsorbed in the PCT?

A

67%

29
Q

What percentage of Na+ is reabsorbed in the TAL (Thick ascending limb of LoH)?

A

25%

30
Q

What is the main driving force for the active reabsorption of Na+ and Cl- in the ascending limb of LoH?

A

Concentration gradient

Due to concentration of Na+ and Cl- in the descending limb (only H2O reabsorption)

31
Q

What part of the tubule is the main site of Ca2+ reabsorption?

A

Distal convoluted tubule

32
Q

What happens to Ca2+ once it has been reabsorbed into the tubular cell?

A
  • Binds to Calmodulin

- Moves across basolateral membrane via NCX

33
Q

What regulates Ca2+ reabsorption from the tubule lumen?

A

PTH

1,25-OH2 Vitamin D (Calcitriol)

34
Q

Is the fluid entering and leaving the Distal convoluted tubule hypo- or hyper-osmotic?

A

Hypo-osmotic

35
Q

Name the tubular cells lining the cortical collecting duct:

A
  • Principle cells (70%)
  • alpha Intercalated cells
  • beta Intercalated cells
36
Q

Name the most common cell lining the cortical collecting duct:

A

Principle cells

37
Q

What ions are reabsorbed/secreted by the principle cells (lining the cortical collecting duct):

A

Na+ and Cl- are reabsorbed

K+ is secreted

38
Q

Describe the mechanism of Na+ and Cl- reabsorption across Principle cells:

A

Na+ is reabsorbed across the apical membrane via ENaC, and across the basolateral membrane via Na+/K+-ATPase
This drives paracellular Cl- uptake (due to electrochemical gradient)

39
Q

What ions are secreted from Principle cells, and via which channel?

A

K+

ROMK

40
Q

Name the cells of the cortical collecting duct which secrete acid:

A

alpha Intercalated cells

41
Q

Name the channels in the apical membrane of alpha intercalated cells:

A

ACID SECRETING CELLS:

  • H+-ATPase
  • H+/K+-ATPase
42
Q

Name the cells of the cortical collecting duct which secrete bicarbonate:

A

beta Intercalated cells

43
Q

Name the channels on the apical membrane of beta Intercalated cells:

A

BICARBONATE SECRETING:

  • Na+/Cl-/HCO3- exchanger
  • Cl-/HCO3- exchanger
44
Q

What part of the tubule is lined by intercalated cells?

A

Cortical collecting duct

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