Urinary 2 - Renal reabsorption Flashcards Preview

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

Where does the majority of reabsorption occur?

Proximal Convoluted Tubule

2

Where does 65% H2O reabsorption occur?

PCT

3

Where does 100% Glucose and amino acid reabsorption occur?

PCT

4

What channel in the basolateral membrane drives renal reabsorption?

Na+/K+-ATPase

5

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

1 - Na+-Glucose symporter (SGLUT)
2 - Na+/H+ antiporter

6

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

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

7

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

Na+/Cl- symporter (NCC)

8

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

ENaC

9

What substances are secreted into the tubules?

- K+
- H+
- Organic anions and cations

10

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

via H+ antiporter

11

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

- Acetylcholine
- Dopamine
- Adrenaline
- Histamine
- Serotonin

12

Name a few drugs that are secreted into the tubule:

- Sulfonamines
- Morphine
- Atropine
- Isoproterenol
- Penicillin
- Salicylate
- NSAIDs

13

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

- Urate
- Bile salts
- Fatty acids

14

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

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

15

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

PCT

16

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

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

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

Bowman's Capsule

18

Name the 2 types of nephrons:

1) Juxtamedullary
2) Cortical

19

What type of nephron is most common?

Cortical (80%)

20

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

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

21

Name the main ions reabsorbed in the distal tubule:

Na+
Ca2+
Cl-

22

What is reabsorbed in the descending LoH?

Only H2O

23

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

Thick ascending limb (TAL)

24

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

Thick ascending limb of LoH (TAL)

25

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

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

26

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

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

27

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

Renal Outer Medullary K+ channel
TAL (Thick ascending limb of LoH)

28

What percentage of Na+ is reabsorbed in the PCT?

67%

29

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

25%

30

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

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

31

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

Distal convoluted tubule

32

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

- Binds to Calmodulin
- Moves across basolateral membrane via NCX

33

What regulates Ca2+ reabsorption from the tubule lumen?

PTH
1,25-OH2 Vitamin D (Calcitriol)

34

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

Hypo-osmotic

35

Name the tubular cells lining the cortical collecting duct:

- Principle cells (70%)
- alpha Intercalated cells
- beta Intercalated cells

36

Name the most common cell lining the cortical collecting duct:

Principle cells

37

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

Na+ and Cl- are reabsorbed
K+ is secreted

38

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

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

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

K+
ROMK

40

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

alpha Intercalated cells

41

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

ACID SECRETING CELLS:
- H+-ATPase
- H+/K+-ATPase

42

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

beta Intercalated cells

43

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

BICARBONATE SECRETING:
- Na+/Cl-/HCO3- exchanger
- Cl-/HCO3- exchanger

44

What part of the tubule is lined by intercalated cells?

Cortical collecting duct