The region of a nephron where P cells (principal cells) are located is:
Collecting ducts have 2 cell populations: P cell / principle cell: Reabsorb Na+Secrete K+ Intercalated cell: Absorb K+Secrete H+, HCO3- it is the buffering cell in the kidney.
PCT
Loop of Henle
DCT
Collecting duct
Excretory System (Kidney, Bladder) Acid-Base Balance