ANATOMY

Detailed explanation-1: -Urea is not reabsorbed during urine formation.

Detailed explanation-2: -Urea is an end product of protein catabolism by the liver with a molecular mass of 60 Da. Urea is freely filtered by the glomerulus and then passively reabsorbed in both the proximal and distal nephrons.

Detailed explanation-3: -Urea is concentrated within the collecting-duct lumen (by water reabsorption) until it reaches the terminal IMCD, where it is reabsorbed by the urea transporters UT-A1 and UT-A3.

Detailed explanation-4: -Urea is not reabsorbed into the blood capillaries that surround the tubule of a nephron.

Detailed explanation-5: -Most of the reabsorption of solutes necessary for normal body function, such as amino acids, glucose, and salts, takes place in the proximal part of the tubule. This reabsorption may be active, as in the case of glucose, amino acids, and peptides, whereas water, chloride, and other ions are passively reabsorbed.