Anatomy & Physiology

Anatomy & Physiology Study Guide

Chapter 24: The Urinary System 24.1 The Kidneys The kidneys are bean–shaped, glandular organs about four inches long by two inches wide by one inch thick. They are found on the abdomen’s posterior wall against the muscles of the back on each side of the vertebral column, under the diaphragm, and behind the peritoneum (retroperitoneal). The right kidney is usually lower than the left. The kidney is supported by the peritoneum anteriorly and by perirenal connective tissue posteriorly and laterally. The ribs help to protect the kidneys.

©2018 Achieve Page 331 The hilum of the kidney is the region in which the large renal artery and renal vein enter the kidney at a central notch. The kidney is made of an outer shell, called the cortex , and the renal pelvis, which is a hollow inner chamber. The cortex is made up of more than a million tiny filtration plants called nephrons. The medulla is made up of a series of striated, conical masses called the renal pyramids. The number of pyramids varies from 8-18 in each kidney, and they are positioned with their bases directed to the kidney’s circumference, and their tops toward the pelvis. The kidney’s pelvis is drained by a tube called the ureter, which leaves the kidney at its hilum. Urine is drained from the of 368