1. Human Excretory System

2. Homeostasis
Process of maintaining ideal internal conditions (correct temp, right amount of water, glucose, and other solutes) for body to work at peak
Excretion is the process of removing metabolic waste products and other toxins
Secretion is the release of useful substances, e.g. hormones from body.

3. Removal of Waste Products
Some waste becomes highly toxic if it is allowed to accumulate. This could damage some tissues.
Excess water could also lead to a number of complications
Waste products must be removed.
They are continually moved into the bloodstream, which carries them to the excretory organs.

4. Excretory Organs Four main excretory organs:
Lungs
Colon
Skin
Kidneys
The liver is not an excretory organ, but it does produces products which are excreted elsewhere. Toxins and drugs as well as alcohol are broken down in the liver. Because of this, excess smoking, medication and alcohol is extremely harmful to the liver.

5. The Lungs
Carbon dioxide released from cellular respiration is carried to the lungs in the blood. It then diffuses across the respiratory membrane and is exhaled.
A small amount of heat and water is excreted this way.

6. The Colon
Bile pigments, from the break down of hemoglobin, and cholesterol are synthesized in the liver.
They pass into the small intestine as bile and are excreted in feces as bile salts from the colon.
Mucus and bacteria also excreted through the colon.

7. The Skin Sweat, contains water, salt and some urea
As the water in the sweat is excreted, heat is lost and the body is cooled.
Sweat is a form of excretion as it rids the body of waste as well of a form of secretion as it maintains body temperature.

8. The Kidneys
When amino acids and nucleic acids are broken down, nitrogenous waste is released as ammonia, urea, uric acid and creatinine.
Ammonia is toxic if it accumulates. It gets converted to urea in the liver.

9. Made in the Liver, Excreted by the Kidneys
Urea- main nitrogenous waste compound secreted. It is formed by the breakdown of excess amino acids in the process of deamination.
Uric Acid- nitrogenous end product of nucleic acid metabolism.
Creatinine- formed from creatinne phosphate, found in muscle cells.
Non-nitrogenous waste, CO2 excess water, ions, hormones, poisons and drugs.

10. Urinary System
Main function is to maintain homeostasis by regulating the volume and concentration of body fluids.
Filters and reabsorbs certain materials from blood.
Made up of:
Two Kidneys
A Bladder
A Urethra

11. Urinary System: Kidneys
Kidneys aid in:
Excretion as they filter waste out of blood
Regulation of water and salt balance in body
Essentially, they filter the blood.
Each kidney contains:
Renal artery: carries waste products to the kidney and supplies the kidneys with oxygen and nutrients.
A renal vein that contains the purest blood in the body. Carries CO2 to the inferior vena cava
Ureter that carries urine from the kidney to the bladder.
Nephrons

12. Nephrons Functional unit of the kidney.
Each kindey contains about 1 million nephrons.
The kidney as a whole does not filter the blood, each of the individual nephrons filter the blood.
Nephrons make urine

13. Urine
Made up mostly of:
Water
Salt
Urea
Sweat is made up mostly of:

14. Urinary System Bladder
Stores urine
Is stimulated by impulses from a motor nerve, to contract to expel the urine.
Has sphincter muscles at the base to control the flow of urine.

15. URINE Waste drains out of the kidneys in the form of urine.
Urine is about 95% water and 5% urea (protein from protein breakdown).
Fresh urine has no bacteria in it. It is quite clean (probably cleaner than your hands).

16. Urinary System: Urethra
Carries urine from the bladder to outside the body.