It briefly describes how urine is produced (glomerular filtration, reabsorption, and tubular secretion) and what happens to sodium at the renal level. The mechanisms of sodium (salt) reabsorption via transcellular (transepithelial) and paracellular are described. The importance of the sodium gradient created by the basolateral Na / K ATPase, the mechanisms of cotransportation of Na-glucose (SGLT) and Na-anions (OAT), and the countertransportation of Na-H (NHE) of the membrane are explained. apical of the proximal tubule. The Na-HCO3 cotransporter (NBC) of the basolateral membrane of the proximal tubule is presented. In addition, the Na, K and Cl cotransporter (NKCC) and the Na-H antiporter (NHE) of the apical membrane of the dilutor segment are shown. Finally, the effect of aldosterone and atrial peptide on salt reabsorption in the distal nephron and how this renal excretion of salt is related to the maintenance of blood volume or extracellular fluid volume is explained. I share the link of my channel.    / @mauriciogiuliodori