1. EXCRETION

2. Excretion is: removal of wastes removal of excess heat
Main Excretory organs involved are:
kidneys
liver
lungs
skin

3. Human Excretion Liver’s role Detoxification-
changes harmful substances into inactive or less poisonous substances
These inactive substances are returned to blood and are filtered by kidneys.

4. Liver continued
Liver – removes harmful substances from the blood such as bacteria, certain drugs, and hormones
The liver breaks down excess amino acids to form urea
Bile is considered an excretory product of the liver

5. A healthy liver and the liver of a person with cirrhosis

6. Urinary System Kidneys 2 main functions Remove wastes
Kidneys-> ureter-> urinary bladder-> urethra
Kidneys
2 main functions
Remove wastes
2. Regulate the concentrations of substances found in the body fluids
*****If kidneys cannot perform these functions a person will die.*****

8. Urine- final waste fluid excreted
Made up of water, urea and various salts.
1-1.5 liters of urine are produced every 24 hours
Urinary System Parts
Ureter- tube connects kidney to urinary bladder
Function –conducts urine from kidney to bladder
Urinary Bladder- collects and stores urine for
Excretion
Urethra- during urination urine travels from the bladder to the outside of the body

9. Lungs- remove CO2 and water (water vapor) from cellular respiration
Skin-
Functions:
Protection-
barrier from microorganisms and other foreign materials
prevents body from drying out

10. Skin Small amounts of urea and salts in sweat
2. Excretion-
Small amounts of urea and salts in sweat
Removal of excess heat (Major Function)
Blood vessels dilate bringing more warm blood to skin surface
Sweat is produced by sweat glands
Sweat absorbs body heat and evaporates to water vapor and body heat leaves the body in the water vapor
Body cools as a result of the evaporation

11. Skin-Review Skin - major role in excretion is removal of excess heat
When the body becomes too warm, extra heat is lost
Evaporation of sweat removes heat and cools the body

12. The skin is the largest organ in the body
It contains sweat glands through which sweat is released
Sweat is made up of:
98% water
2% salt
Small amounts of urea

15. Excretion disorders
Renal Failure- kidneys stop filtering the blood and wastes and fluid build up in the body and death can result
Treatment- dialysis- artificial machine filters and cleans the blood
*Presence of protein, sugar or other needed substances indicating other conditions such as diabetes and cardiovascular disease

16. Excretory Disorders
Kidney stones - result when urine becomes too concentrated and substances in the urine crystallize to form stones
Renal Failure – results when the kidneys fail to function correctly which leads to abnormal levels of fluids in the body

17. Examples of kidney stones

18. Kidney dialysis averages 4 hours per session, 3 times per week.

20. Discussion Questions What does the excretory system do?
The excretory system eliminates wastes from the body and regulates the level of fluids in the body.
What body systems make up the excretory system?
urinary system, respiratory system, and integumentary system
What is the function of the urinary system?
Answers should reflect an understanding that the urinary system produces, temporarily stores, then removes liquid waste from the body and helps maintain homeostasis.

21. Discussion Questions
How do the ureters, bladder, and urethra work together to excrete urine?
Urine leaves the kidney through the ureters. The urine is stored in the bladder and then leaves the bladder through the urethra.
How does the excretory system interact with the nervous system?
The hypothalamus, a part of the nervous system, controls the secretion of some hormones, including a hormone that helps the kidneys regulate fluid levels.