1. Excretory System

2. What is the excretory system?
The organs that remove metabolic wastes from the body
Skin
Lungs
Liver
Kidneys

3. Skin The skin secretes excess salt, water and a small amount of urea
Urea is a toxic compound that is produced by the breakdown of amino acids to produce energy.

4. Lungs
The lungs rid the body of excess carbon dioxide.

5. Liver
The liver converts excess nitrogen-containing compounds into urea.
Urea is easily excreted by the kidneys.

6. Kidneys
Kidneys remove wastes from the blood while regulating the amount of salt and water in the blood.
One functional kidney is required for life.

7. Gross Anatomy of Kidneys
Located next to the spinal column in the lower back
Acts as a pressure based blood filter.
Ureter
Tube that connects the kidneys to the bladder

8. Gross Anatomy of the Kidneys
Bladder
A saclike organ that stores urine before being excreted.
Urethra
Tube that connects bladder to the outside of the body

9. Microscopic Anatomy of the Kidney
Nephron – the functional, filtering units of the kidney
Glomerulus
Small network of capillaries
Bowman’s Capsule
Hollow, cup-shaped structure surrounding the glomerulus
Parts of a nephron

10. Filtration of the blood
Blood is forced under pressure through the glomerulus.
Water, salt, sugars, amino acids and urea are forced out of the blood into the Bowman’s capsule.
These materials are called the filtrate.

11. Reabsorption
The filtrate moves through the Loop of Henle – a thin tube that connects the Bowman’s Capsule to the collecting duct which is surrounded by capillaries.
Most of the water and nutrients are captured by capillaries.

12. Urine Formation Useful materials are returned to the blood.
Waste materials flow to the collecting duct where they are shunted to the ureter, forming urine.

13. Urine Testing Most drugs are excreted by the kidneys.
Tests on urine can show what drugs a patient has taken.
Urine tests can also be used to detect health problems like diabetes.