Orc2-5 binds strongly; Orc6 binds weakly to ARS and has a nuclear localization signal that must be activated by the cyclin/ CDK kinase during the G1 to S transition.

TLS Online TPP Program

#Id: 5555

#Unit 7. System Physiology – Animal

Type A intercalated cells  secrete hydrogen ions by a hydrogen-ATPase transporter and by a hydrogen-potassium-ATPase transporter are especially important in eliminating hydrogen ions while reabsorbing bicarbonate in acidosis

TLS Online TPP Program

#Id: 5556

#Unit 7. System Physiology – Animal

Type B intercalated cells have functions opposite to those of type A cells and secrete bicarbonate into the tubular lumen while reabsorbing hydrogen ions in alkalosis

TLS Online TPP Program

#Id: 5557

#Unit 7. System Physiology – Animal

The changes in osmolality and volume in the collecting ducts depend on the amount of vasopressin acting on the ducts.

TLS Online TPP Program

#Id: 5558

#Unit 7. System Physiology – Animal

The key to the action of vasopressin on the collecting ducts is aquaporin-2 & stored in vesicles in the cytoplasm of principal cells

TLS Online TPP Program

#Id: 5559

#Unit 7. System Physiology – Animal

The effect is mediated via the vasopressin V2 receptor, cyclic adenosine 5-monophosphate (cAMP) & protein kinase A

TLS Online TPP Program

#Id: 5560

#Unit 7. System Physiology – Animal

Medullary collecting duct is permeable to urea, and there are special urea transporters that facilitate urea diffusion across the luminal and basolateral membranes