Describe the location and structural composition of the kidneys. Describe the structure of the kidneys' individual excretory units.
Each of the two kidneys, which are located in the back of the abdominal cavity, has two layers: the cortex and the medulla. Each kidney is made up of masses of individual excretory units, the nephrons. A nephron consists of a Bowman's capsule, a proximal convoluted tubule, and a distal convoluted tubule, all three of which are located in the renal cortex. The two convoluted tubules are connected by the loop of Henle, which lies in the renal medulla. Distal convoluted tubules empty into collecting tubules, which also lie in the medulla and which empty into the kidney's central cavity, the pelvis.
