Page:Laboratory Manual of the Anatomy of the Rat (Hunt 1924).djvu/98



The reproductive and excretory organs are closely associated in structure and function, and are therefore collectively termed the urogenital, or urinogenital, system. In dissecting the urogenital organs be careful not to cut the blood vessels, which will be studied later.

The two kidneys are the two principal excretory organs of the body. The renal arteries carry the blood to the kidneys, where urea, salts, excess water, etc. are removed from the blood, which then passes to the inferior vena cava through the renal veins. Each kidney is a bean-shaped organ, covered ventrally by peritoneum, and attached to the dorsal wall of the abdomen. The hilum, or depression where the renal blood vessels and ureter enter, is on the median surface. The dorsal surface is flattened, the ventral surface is convex. The anterior end of the right kidney fits into the concave surface of the right lateral lobe of the liver. The left kidney is displaced caudad, so that its hilum is slightly posterior to the level of the posterior end of the right kidney. This displacement is probably due to the presence of the stomach on the left side of the body. The ureter is the tubule which conveys the urine from the kidney to the urinary bladder. Find where it leaves the hilum of the kidney and trace it back to the bladder.

The suprarenal gland is a somewhat hemispherical body immediately anterior to each kidney. It lacks a duct. The secretion (adrenalin) known as an internal secretion, enters the blood, which carries it to those parts of the body where it performs its functions.