Glomerular capillaries

Renal glomerulus
The glomerulus (red) within Bowman's capsule
Details
Precursor	Metanephric blastema
Identifiers
Latin	glomerulus renalis
MeSH	A05.810.453.324.359
Dorlands /Elsevier	g_07/12394744
FMA	15624
Anatomical terminology []

A glomerulus (RP /ɡlɒˈmɛrjuːləs/, US: /ɡlɒˈmɛrrələs/) is a network (as a tuft) of capillaries located at the beginning of a nephron in the kidney. It serves as the first stage in the filtering process of the blood carried out by the nephron in its formation of urine.

The glomerulus is surrounded by a cup-like sac known as Bowman's capsule. The blood plasma is filtered through the capillaries of the glomerulus into the capsule. The Bowman's capsule empties the filtrate into the proximal tubule that is also part of the duct system of the nephron.

A glomerulus receives its blood supply from an afferent arteriole of the renal circulation. Unlike most other capillary beds, the glomerulus drains into an efferent arteriole rather than a venule. The resistance of these arterioles results in high pressure within the glomerulus, aiding the process of ultrafiltration, where fluids and soluble materials in the blood are forced out of the capillaries and into Bowman's capsule.