Fig. 1.

Schematic diagram of the nephron system (not to scale). The model includes one representative superficial nephron and five representative juxtamedullary nephrons, each scaled by the appropriate population ratio. Only the superficial nephron and one juxtamedullary nephron are shown. Along each nephron, the model accounts for the transport of water and 15 solutes (see text). The distal tubule is divided into the early and late portions of the distal convoluted tubule (DCT). The diagram displays only the main Na⁺, K⁺, and Cl⁻ transporters. Red boxes highlight model membrane transporters whose expressions differ between male and female subjects. PCT, proximal convoluted tubule; SDL, short or outer medullary descending limb; mTAL, medullary thick ascending limb; cTAL, cortical thick ascending limb; CNT, connecting tubule; CCD, cortical collecting duct; OMCD, outer-medullary collecting duct; IMCD, inner medullary collecting duct; LDL, thin descending limb; LAL, thin ascending limb.