Question

The activity of the kidneys is controlled by hormones and by the a. volume of nutrients. c. composition of the blood. b. volume of filtrate. d. composition of the urine.

Answer 1

The activity of the kidneys is controlled by hormones which have been released by a gland in the brain and by the composition of the blood.

The kidney, better yet, a kidney nephron has three main functions: ultrafiltration, in which contents of the blood are filtered according to their size (Bowman's Capsule); reabsorption, in which needed substances (water, glucose, amino acids, some salts; unneeded: urea, uric acid, some salts) diffuse (by active transport) into the venule end of a capillary bed (renal tubules and, partially, Henle's Loop as well as the collecting duct); osmoregulation, in which ADH (antidiuretic hormone) is released by the pituitary gland in the brain (renal tubules and, partially, Henle's Loop as well as the collecting duct).

The kidney has more than one activity, so several things perform the activities.