Principal parts of the kidney

The venous system of the kidneys generally follow the same paths as the arteries. Venous blood passes through the interlobular, arciform, interlobar, and renal veins (fig. 1-56). NEPHRONS.—The functional units of the kidneys are called nephrons. There are about 1 million nephrons in each kidney. Each nephron consists of a renal corpuscle and a renal tubule (fig. 1-56, view C). The renal corpuscle (Malpighian corpuscle) is composed of a tangled cluster of blood capillaries called a glomerulus. The glomerulus is surrounded by a sac-like structure referred to as the glomerulus capsule or Bowman's capsule (figs. 1-56, view C, and 1-57). Leading away from the glomerulus is the renal tubule. The initial portion of the renal tubule is coiled and called the proximal convoluted (meaning coiled or twisted) tubule. The proximal convoluted tubule dips down to become the descending loop of Henle. The tubule then curves upward toward the renal corpuscle and forms the ascending loop of Henle. Once the ascending limb reaches the region of the renal corpuscle, it called the distal convoluted tubule. Several distal convoluted tubules merge in the renal 1-54 HM3F0156 RENAL PYRAMID RENAL CAPSULE RENAL CORTEX RENAL MEDULLA MINOR CALYX MAJOR CALYX RENAL PELVIS RENAL ARTERY RENAL COLUMN RENAL VEIN RENAL PAPILLA RENAL PYRAMID URETER RENAL CORPUSCLE COLLECTING DUCT RENAL TUBULE ASCENDING LOOP OF HENLE DESCENDING LOOP OF HENLE GLOMERULUS (BOWMAN'S CAPSULE) A B NEPHRONS RENAL CORTEX RENAL MEDULLA PAPILLARY DUCT MINOR CALYX C Figure 1-56.—Principal parts of the kidney: A. Longitudinal section of a kidney; B. A renal pyramid containing nephrons; C. A single nephron.