Urinary System
MAIN FUNCTIONS
• Ammonia (formed by the breakdown of old
proteins) is converted to urea in kidneys
• Cleans the blood by removing urea, excess salts,
water and metabolic wastes and excreting them
as urine
• Keeps the volume of water in your body constant
• Regulate blood pressure by renin (enzyme)
• Stimulate production of RBCs by erythropoietin
• Increase calcium absorption by calcitriol (vit. D)
MAIN STRUCTURES
Kidneys – filter blood
and remove waste
(maintain
homeostasis)
Nephron – filtering
unit of the kidney
(each kidney has a
million nephrons)
MAIN STRUCTURES CONT.
Renal Capsule –
connective tissue that
surrounds each kidney
Renal Cortex – outer
part, lighter in color;
contains parts of
nephrons
Renal Medulla –
middle, darker part;
contains parts of nephrons
Renal Pelvis – inner part, http://www.biologymad.com/re
collecting region of urine sources/kidney.swf
MAIN STRUCTURES CONT.
Ureter – tube that takes
urine from kidneys to
urinary bladder
Urinary Bladder –
stores urine
Urethra – allows urine
to pass from the
urinary bladder out of
the body
Factors that affect kidney
function
• Antidiuretic hormone (ADH) – prevents excess
water loss from kidneys
• Alcohol – inhibits secretion of ADH = more
urine volume
• Aldosterone – prevents excess loss of sodium and
water from kidneys
• Caffeine – increases rate of salt and water loss
from kidneys
• Increased blood pressure – increase rate of water
loss from kidneys.