1. Human Excretory System
Name: ___________________
Date: __________________

2. Excretion – removes cellular waste
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.
Kidneys
Skin
Liver
Lungs

4. Four 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 liver (via the intestines) excretes bile pigments that result from the destruction of hemoglobin. It also converts nitrogenous waste from the break down of proteins into urea.
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.

5. Cellular Waste Heat Water Salts Carbon Dioxide (CO2 ) Urea
W/O excretion poisonous wastes build up in blood, cells, and tissues.
Could lead to serious illness & eventually DEATH!

6. Liver – Some Functions Functions in Excretion Detoxifies Blood
Filters Bacteria, alcohol, drugs, toxic substances
Changes them into inactive or less toxic forms.
Excretes Bile
Contains
Worn-out RBC
Bile salts
Cholesterol

7. Liver Produces Urea Functions in Excretion Forms Urea
Changes toxic wastes (ammonia – from break down of amino acids) to Urea.
Urea  Blood  Kidneys
Filtered out & excreted in Urine

8. Lungs –Main Function Alveoli - Exchange O2 & CO2 between air and
blood (through process of diffusion)
Lungs excrete Carbon dioxide (CO₂) when you
EXHALE

9. Skin
Sweat Glands
Help cool body: Heat escapes through millions of pores in skin surface
Excrete perspiration (evap. cooling)
99% H2O
Mineral Salts
Urea

10. Kidneys & Urinary System
Urinary System – excretes waste and maintains homeostasis of body fluids.
Kidneys (main organ of the system)
Ureters
Bladder
Urethra

11. Kidneys & Urinary System
Two
Fist sized
Bean shaped

12. 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…)

13. Urinary System - continued
Ureters
Narrow muscular tubes
Connect Kidney  Bladder
Bladder
Muscular sac
Stores Urine
Expand to fill
Muscle relaxes
Urine squeezed into Urethra

14. Urinary System - endpoint
Urethra
Tube leading from Bladder  outside of body

15. 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)