Glomerulus

The glomerulus is a capillary bed found surrounded by the Bowman's capsule of the nephron in the vertebrate kidney. Blood is fed to the glomerulus through the afferent arteriole, and empties into the efferent arteriole.

The difference in pressure between the afferent arteriole and efferent arteriole results in the process of ultrafiltration where soluble materials in the blood are forced out into the Bowman's capsule forming the filtrate that eventually becomes urine after being processed by the rest of the nephron.