Download 37.3: The Urinary System

What liquid waste do we make?
 Digesting protein makes poison
nitrogen waste = ammonia = poison
H
O
|
H
||
N —C—C—OH
|
H
H
NH2 = ammonia
CO2 + H2O
Nitrogen waste disposal
need to save H2O
evolved less poisonous waste
product than ammonia
Ammonia  urea
excrete urea & H2O as urine
Kidneys: Structure and Function
Filter the blood to
remove wastes from it,
regulate salt & water
balance & maintain
blood pH thus
maintaining the
homeostasis of body
fluids
Located just above waist
near back on both sidesvulnerable (redundant)
Urinary sytem
 Urine pathway:
Kidney->Ureter->Urinary
bladder->Urethra
Ureters: Tubes that carry
urine from kidneys to
urinary bladder
Urinary bladder: smooth
muscle bag that stores
urine
Urethra: urine passes out of
the body through this
tube
Ureter
Bladder
Urethra
Kidney
Nephron: The unit of the kidney
 Microscopic functional
unit of kidney (approx.
1million per kidney)
 Inverse concentration
process
Skin: largest excretory organ
 The skin removes many
contaminants
 Sweat (sudoriferous)
glands flush salts, urea,
& lactic acid from blood
 Sebaceous (oil) glands
release lipids from
blood