22: Urinary System
Thumbnail Image Credit: Kidney Cross Section by Holly Fischer is licensed under CC BY 3.0 .
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- 22.2: Overview of the Kidney
- The kidneys lie on either side of the spine in the retroperitoneal space between the parietal peritoneum and the posterior abdominal wall, well protected by muscle, fat, and ribs. Each kidney has an outer cortex and an inner medulla. Because the function of the kidneys is to filter out waste products from the blood, kidneys are well vascularized, receiving about 25 percent of the cardiac output at rest.
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- 22.3: Microscopic Anatomy of the Kidney
- The renal structures that conduct the essential work of the kidney cannot be seen by the naked eye. Only a light or electron microscope can reveal these structures. Even then, serial sections and computer reconstruction are necessary to give us a comprehensive view of the functional anatomy of the nephron and its associated blood vessels.
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- 22.4: Urinary Tract
- Rather than start with urine formation, this section will start with urine excretion. Urine is a fluid of variable composition that requires specialized structures to remove it from the body safely and efficiently. Blood is filtered, and the filtrate is transformed into urine at a relatively constant rate throughout the day. This processed liquid is stored until a convenient time for excretion.