Glomerulus (kidney)

The glomerulus (pl.: glomeruli) is a network of small blood vessels (<a href="/facts/Capillaries/4BIzKJAe">capillaries</a>) known as a tuft, located at the beginning of a <a href="/facts/Nephron/ss24U1zW">nephron</a> in the <a href="/facts/Kidney/HBspPrv9">kidney</a>. 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 <a href="/facts/Intraglomerular_mesangial_cell/tjTSmyST">intraglomerular mesangial cells</a>. The <a href="/facts/Blood/03zEulkj">blood</a> is filtered across the capillary walls of this tuft through the glomerular filtration barrier, which yields its <a href="/facts/Ultrafiltration_(renal)/ky8HcoJs">filtrate</a> of water and soluble substances to a cup-like sac known as <a href="/facts/Bowman%2527s_capsule/mvJx1IEJ">Bowman's capsule</a>. The filtrate then enters the <a href="/facts/Nephron/ss24U1zW">renal tubule</a> of the nephron.
The glomerulus receives its blood supply from an <a href="/facts/Afferent_arteriole/SnvITfVb">afferent arteriole</a> of the renal arterial circulation. Unlike most capillary beds, the glomerular capillaries exit into <a href="/facts/Efferent_arteriole/ctPrt7jm">efferent arterioles</a> rather than <a href="/facts/Venule/L4uIvXuo">venules</a>. The resistance of the efferent arterioles causes sufficient hydrostatic pressure within the glomerulus to provide the force for <a href="/facts/Ultrafiltration_(renal)/ky8HcoJs">ultrafiltration</a>.
The glomerulus and its surrounding <a href="/facts/Bowman%2527s_capsule/mvJx1IEJ">Bowman's capsule</a> constitute a <a href="/facts/Renal_corpuscle/A5tQAMan">renal corpuscle</a>, the basic filtration unit of the kidney. The rate at which blood is filtered through all of the glomeruli, and thus the measure of the overall kidney function, is the <a href="/facts/Renal_function/PFmxX01G">glomerular filtration rate</a>.

Glomerulus (kidney) open-in-new

Glomerulus (kidney)