Histology Guide

virtual microscopy laboratory

Chapter 16 - Urinary System

The urinary system (also known as the renal system) consists of the kidneys, ureters, urinary bladder, and the urethra. Its main function is the production, storage, and expulsion of urine.


The kidney is involved in the formation of urine and regulation of pressure, volume, and pH of blood.

Nephrons are the functional units of the kidney. Each nephron includes a filter, called the renal corpuscle, and a single, long tubule through which the filtrate passes before emerging as urine.

The renal tubules of a nephron consist of a proximal convoluted tubule, loop of Henle, and distal convoluted tubule.

Renal Vasculature

Despite their relatively small size, the kidneys receive almost 20% of the cardiac output.

Urinary Bladder

The urinary bladder is a muscular sac that stores urine, allowing urination to be infrequent and voluntary. It is lined by transitional epithelium (urothelium).