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Flashcards in Tubular Function Deck (17):

Vasopressin is involved in

water balance, it increased reabsorption of water


Aldosterone is involved in

sodium and potassium balance


Angiotension II is involves in

sodium and acid-base balance


Parathyroid hormone is involved in

calcium and phosphate


What is reabsorbed in the proximal tubule?

water, sodium and potassium 70%
all the glucose and 75% bicarbonate


What is reabsorbed in the Loop of Henle

15% water and bicarbonate, 20% sodium or potassium, no glucose


What is reabsorbed in the Distal tubule and Collecting Duct

15% water, 10% sodium, bicarbonate, no glucose and excrete whatever is left of potassium


Tubular Reabsorption and Secretion is driven by

Na-K-ATPase on the basolateral membrane


Absorption into cell across lumenal membrane is _____ and driven by the _________ gradient of _______

passive, electrochemical, sodium


Secretion across lumenal membrane into the tubule is _____ driven by _____ movement in the opposite direction

passive, sodium


Transport of solutes coupled to sodium may be _____ an electrochemical gradient, called ______ active transport, but not ____

against, secondary, ATP


Describ the Proximal Tubule.

Site of bulk absorption. uses NHE3 sodium transporter (used for bicarbonate reabsorption). Only place where glucose, aminoacid and phosphate cotransporters are located. and Very leaky.


Describ the ascending limb to the loop of henle

reasorbs 20-30% sodium, transport protein NKCC2 (stopped by diruretic furosemide), impermeable to water, fluid leaving ascending limb is always less concentrated than plasma (passive diffusion by osmotic gradient)


Describe DIstal Convolated Tubule

reabsords 5-10% sodium, sodium transporter NCC, inhibited by directics thiazides (less potent than furosemide)


Collecting Duct

Reabsorbs 1-3% of filtered sodium, sodium channel ENaC, Aldosterone receptors= increases sodium reabsorption. Vasopressin receptors - increases water reabsorption
less permeable to cholride in order to secrete excess potassium SO it is the site of regulating the excretion of: Sodium, potassium, water and ammonium


Describe early proximal tubule and glucose

uses SGLT II, one Na to one GLucose (not as strong absorption of glucose at the late proximal tubule


Describe the late proximal tubule and glucose

uses SGLT I, one Na to Two Glucose, so it absorpbs the rest of the glucose so that there is none in the urine