2. Excretory System
Excretion – removes cellular waste
The process that collects & removes
harmful or useless substances that
form in the body or are taken into the
body from the blood, tissues, and cells.
3. Excretory System
Although the urinary system has a major role in
excretion, other organs contribute to the excretory
function.
4. Three Organs of the Excretory System
•The lungs in the respiratory system excrete some
waste products, such as carbon dioxide and water.
•The skin is another excretory organ that rids the
body of wastes through the sweat glands.
•The major task of excretion still belongs to the
kidneys, the major organ in the urinary system. If it
fails the other organs cannot take over and
compensate adequately.
6. Lungs –Main Function
Alveoli - Exchange O2 & CO2 between air and
blood (through process of diffusion)
Lungs excrete CO2 when you EXHALE
7. Skin
Sweat Glands
Help cool body: Heat escapes through millions of
pores in skin surface
Excrete perspiration (evap. cooling)
99% H2O
Mineral Salts
Urea
8. Kidneys & Urinary System
Urinary System – excretes waste and maintains
homeostasis of body fluids.
Kidneys (main organ of the system)
Ureters
Bladder
Urethra
10. Kidneys- Functional Units & Product
Nephron (about one million per kidney)
Microscopic units that filter blood of wastes.
H2O and waste taken from blood into nephron
Form URINE
Glomerulus (clump of capillaries)
At end of each nephron
Network of coiled tubes – diffusion of wastes -
while useful substances & water are reabsorbed
Urine
Pale yellow solution
Urea, H20, salts, other trace solutions (toxins…)
11. Urinary System - continued
Ureters
Narrow muscular tubes
Connect Kidney Bladder
Bladder
Muscular sac
Stores Urine
Expand to fill
Muscle relaxes
Urine squeezed into Urethra
12. Urinary System - endpoint
Urethra
Tube leading from Bladder outside of body
13. Failures of Homeostasis
Bladder & Kidney Infections caused by bacteria from
colon/rectum entering urethra.
Kidney Stones - crystallization of mineral salts & uric
acid that block passage of urine
Kidney Disease - caused by long term diabetes,
infections, & chemical poisoning
Gout – form of arthritis where excess production of
uric acid leads to deposits of crystals in joints (esp.
toes)