Glomeruluskapillaren

Glomeruluskapillaren, or the glomerular capillary, is the dense network of capillaries that forms the glomerulus, a key filtration unit within the kidney. It receives blood from the afferent arteriole and drains into the efferent arteriole. Together with Bowman's capsule it constitutes the renal corpuscle, where blood ultrafiltration begins and the filtrate enters Bowman's space.

The glomerular filtration barrier consists of three layers: the fenestrated glomerular capillary endothelium, the glomerular basement membrane, and the podocytes of the visceral epithelium, with their interdigitating foot processes and slit diaphragms. This barrier permits water, ions, and small solutes to pass while restricting larger proteins and cells. The negatively charged basement membrane contributes to charge selectivity, helping to further limit protein passage.

Filtration is driven by hydrostatic pressure within the glomerular capillaries and is modulated by oncotic pressure of plasma and the pressure in Bowman's space, establishing the glomerular filtration rate (GFR). GFR is regulated by autoregulatory mechanisms, notably the myogenic response of the afferent arteriole and tubuloglomerular feedback, as well as hormonal influences. The high surface area of the capillary tuft supports efficient filtration, producing an ultrafiltrate that becomes urine through subsequent tubular processing.

Cells associated with the glomerulus, including mesangial cells, provide structural support and regulate surface area. Damage to the glomerulus can lead to proteinuria or hematuria and contribute to kidney disease, as seen in conditions such as glomerulonephritis or diabetic nephropathy, which affect the capillary barrier and filtration dynamics.