Glomerulus (kidney)

Glomerulus
Glomerulus (red), Bowman's capsule (blue) and proximal tubule (green)
Details
Pronunciation	/ɡləˈmɛr(j)ələs, ɡloʊ-/
Precursor	Metanephric blastema
Location	Nephron of kidney
Identifiers
Latin	glomerulus renalis
MeSH	D007678
FMA	15624
Anatomical terminology [edit on Wikidata]

The glomerulus (pl.: glomeruli) is a network of small blood vessels (capillaries) known as a tuft, located at the beginning of a nephron in the kidney. Each of the two kidneys contains about one million nephrons. The tuft is structurally supported by the mesangium (the space between the blood vessels), composed of intraglomerular mesangial cells. The blood is filtered across the capillary walls of this tuft through the glomerular filtration barrier, which yields its filtrate of water and soluble substances to a cup-like sac known as Bowman's capsule. The filtrate then enters the renal tubule of the nephron.^[1]

The glomerulus receives its blood supply from an afferent arteriole of the renal arterial circulation. Unlike most capillary beds, the glomerular capillaries exit into efferent arterioles rather than venules. The resistance of the efferent arterioles causes sufficient hydrostatic pressure within the glomerulus to provide the force for ultrafiltration.

The glomerulus and its surrounding Bowman's capsule constitute a renal corpuscle, the basic filtration unit of the kidney.^[2] The rate at which blood is filtered through all of the glomeruli, and thus the measure of the overall kidney function, is the glomerular filtration rate.