Urine formation occurs in 3 stages
FiltrationMovement of water and dissolved substances from blood through a nephron to the Bowman’s capsule
ReabsorptionEssential solutes and water taken from the nephron back into capillaries
SecretionMaterials (i.e., drugs, certain ions, toxins) from blood go back into tubules
Each nephron is supplied with blood by the
afferent arterioles. Nephrons branch into a capillary bed, called the
glomerulus – a cluster of arterioles enclosed in a capsule, called
Bowman’s capsule. Fluids that will eventually become urine
enter the Bowman’s capsule from the blood the capsule tapers to a thin tubule, called the
proximal tubule. Urine is carried from the proximal tubule to the
loop of Henle, which descends into the medulla of the kidney; urine then moves through the
distal tubule, the last segment of the nephron, and into the
collecting ducts – structures that collect urine from many nephrons and this urine is brought to the bladder.
http://wps.prenhall.com/wps/media/objects/488/500640/CDA39_1/CDA39_1c/CDA39_1c.htm http://health.howstuffworks.com/human-body/systems/kidney-urinary/adam-200032.htm
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