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Flashcards in Physiology 5 Deck (19):
1

What are the main anions?

Bicarbonate and Cl-

2

What are the junctions of the proximal tubule?

Tight junctions

3

What happens to tight junctions as we move from proximal to distal tubule?

They become progressively less soluble

4

What is solvent drag?

A process by which the solvents are dragged together with the solutes

5

What does the early proximal tubule specifically absorb?

Bicarbonate

6

What does the late proximal tubule absorb specifically?

Chloride

7

Where is the effective sodium transport in the early proximal tubule?

Transcellularly
- Paracellular is counter-productive

8

Is the lumen negative or positive?

Negative, mainly because of active movement of sodium

9

What is the the voltage of the lumen in the late proximal tubule?

It is +3mV

10

Why is the transepithelial voltage positive in the late proximal tubule?

Chloride is leaving faster than cations creating

11

Is sodium absorbed in the thin ascending limb?

Na+ is reabsorbed via passive diffusion (in response to a concentration gradient) across the tight junctions of Paracellular pathway

12

What happens in the thick ascending limb?

Goes all the way to the juxtaglomerular apparatus.
It is an active process.
It absorbs 25% of filtered sodium chloride

13

What regulates sodium in the distal tubule?

Aldosterone specifically

14

Why is Frusemide is given with K+ supplements?

is blocks Na/K/Cl pump leading to increases excretion of K.
K diffuses into the lumen in exchange for Na at the basolateral membrane

15

Where at H ions secreted?

Proximal tubule
Thick ascending limb

16

What are the two regions were the lumen is positive?

Thick ascending limb
Late proximal tubule

17

How is sodium reabsorbed in the distal tubule?

Na reabsorbed is entirely by transcellular route

18

What effect does thiazide have on the distal convoluted tubule?

The NaCl neutral cotransporter is blocked by thiazide diuretics

19

Why is the concentration gradient important?

It allows for the excretion of a very concentrated urine (even during dehydration one still produces waste products which need to be removed)