Filtrate becomes less concentrated as it flows down the medullary collecting ducts, toward the renal pelvis.
True
False

False.

Explanation:

Medullary collecting ducts courses down from the cortex through the hypertonic medulla before joining the collecting tubules from other nephrons to form a single ureter in each kidney.

It is the principle site of action for ADH (antidiuretic hormone) which stimulates the expression of water channel protien, aquaporin-2 in the cell membrane. ADH causes reabsorption of the water through these channels thus resulting in increased concentration of the filtrate.

Hence, the statement filtrate becomes less concentrated as it flows down the medullary collecting ducts, toward the renal pelvis is completely false.

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