ultrafiltration

blood enters the glomerulus through the afferent arteriole where its under relatively high pressure - the afferent arteriole has a much larger lumen space than the efferent arteriole

the high level of hydrostatic pressure in the glomerulus forces small molecules to pass out of the blood and into the bowman’s capsule

the bowman’s capsule contains specialised cells called podocytes

• there are gaps or pores between the endothelial cells of the capillary

• between the capillary endothelial cells and the podocytes there is a layer of collagen and other proteins - this is called the basement membrane

• podocytes have feet-like extensions called pedicels

• pedicels are wrapped around the outside of the capillary, gaps between the pedicels allow only small molecules to pass through into the bowman’s capsule