Physiology 5 Flashcards
What are the main anions?
Bicarbonate and Cl-
What are the junctions of the proximal tubule?
Tight junctions
What happens to tight junctions as we move from proximal to distal tubule?
They become progressively less soluble
What is solvent drag?
A process by which the solvents are dragged together with the solutes
What does the early proximal tubule specifically absorb?
Bicarbonate
What does the late proximal tubule absorb specifically?
Chloride
Where is the effective sodium transport in the early proximal tubule?
Transcellularly
- Paracellular is counter-productive
Is the lumen negative or positive?
Negative, mainly because of active movement of sodium
What is the the voltage of the lumen in the late proximal tubule?
It is +3mV
Why is the transepithelial voltage positive in the late proximal tubule?
Chloride is leaving faster than cations creating
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
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
What regulates sodium in the distal tubule?
Aldosterone specifically
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
Where at H ions secreted?
Proximal tubule
Thick ascending limb
