THE HUMAN URINARY SYSTEM
Section I. THE KIDNEY
8-1. INTRODUCTION TO THE URINARY SYSTEM
a. The urinary system is a collection of organs to rid the body of nitrogenous
wastes. These nitrogenous wastes are created by the metabolism of proteins.
b. The urinary system includes the organs known as the kidney, the ureters, the
urinary bladder, and the urethra (Figure 8-1). Together, these organs remove the
nitrogenous wastes from the circulating blood, concentrate them into a fluid known as
urine, and eliminate the urine from the body.
8-2. GENERAL ANATOMY OF THE KIDNEY
In the human, there are two kidneys, one right and one left.
a. Location. Both kidneys are attached high up on the posterior abdominal
wall. The left kidney is slightly higher than the right.
b. Shape. In the adult, each kidney measures about 1x2x4 inches. The kidneys
have a kidney-bean shape. That is, they are notched on the medial side, they have a
convex lateral curvature, and their front and rear surfaces are somewhat flat.
c. Capsule. Each kidney is surrounded by a dense FCT membrane called a
d. Internal Structure. When a kidney is cut from side to side, the internal
structure is similar to that in Figure 8-1. There is a fleshy portion surrounding a central
opening. The fleshy portion is divided into an outer cortex layer and an inner medulla.
(1) The medulla consists of a series of pyramids whose apices (peaks) point
into the hollow center of the kidney. The apex (peak) of each renal pyramid is known as