The ascending limb, both the thin & the thick segments is virtually impermeable to water, a characteristic that is important for concentrating the urine.

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#Id: 2659

#Unit 7. System Physiology – Animal

In the thick ascending loop, 

Luminal membrane contains a three-ion cotransporter  known as Na+-K+-2Cl- cotransporter

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#Id: 2660

#Unit 7. System Physiology – Animal

The energy for Na+-K+-2Cl- cotransporter is derived from the low intracellular Na+ gradient, which is maintained by the Na+-K+ ATPase

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#Id: 2661

#Unit 7. System Physiology – Animal

Thick ascending limb is called the diluting segment because NaCl is reabsorbed but water is not reabsorbed along with it.

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#Id: 2662

#Unit 7. System Physiology – Animal

The tubular fluid that leaves the thick ascending limb has a lower Na+ concentration and a lower osmolarity than blood.

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#Id: 2663

#Unit 7. System Physiology – Animal

Recycling of K+ 

Most, but not all, of the K+ that enters the cell through cotransporter leaves the cell across BM, A portion of the K+, diffuses back into the lumen.

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#Id: 2664

#Unit 7. System Physiology – Animal

The thick ascending limb of the loop of Henle is the site of action of the powerful “loop” diuretics.