renal carcinosarcoma  Ultrafiltration (renal)  In biological
terms, ultrafiltration occurs at the barrier between the blood
and the filtrate in the renal corpuscle or Bowman's capsule in
the kidneys. The Bowman's capsule contains a dense capillary
network called the glomerulus. Blood flows into these
capillaries through a wide afferent arteriole and leaves through
a narrower efferent arteriole. The blood pressure inside these
capillaries is high because:    1. The renal artery contains
blood at very high pressure which enters the glomerulus via the
short afferent arteriole.   2. The efferent arteriole has a
smaller diameter than the afferent arteriole.  The high pressure
forces small molecules such as water, glucose, amino acids,
sodium chloride and urea through the filter, from the blood in
the glomerular capsule across the basement membrane of the
Bowman's capsule and into the nephron. This type of high
pressure filtration is ultrafiltration. The fluid formed in this
way is called glomerular filtrate.  Glom