1. Topic: Excretion AIM: How does the process of Excretion aid in the maintenance of Homeostasis?
Do Now: Define & write an Acrostic Poem for the word EXCRETION
Homework: TEXT BOOK
Read Pages Page 599
Questions 1-5

2. What is the Function or Purpose of the Excretory System?
To Rid the body of METABOLIC WASTES!!
Alternate wording: To Rid the body of CELLULAR WASTES!!

3. What are METABOLIC WASTES?
Metabolic wastes are chemical products which are of no use to the body.
In fact, some of them may prove detrimental to health, and accumulation of these waste products can even be fatal.
They are produced by different cellular activities.
Can you name some Metabolic wastes?

4. Metabolic Wastes
Carbon Dioxide
Sweat
Ammonia
Urine

5. What are the Components of the EXCRETORY SYSTEM
Kidneys
Skin
Lungs
Liver

6. Explain the processes that produce these Metabolic Wastes.
CO2: Produced from the process of Cellular Respiration
Ammonia: The breakdown of excess Amino Acids in the Liver. (DEAMINATION)
Urea: The breakdown of excess of Amino Acids in the Liver. (DEAMINATION)
Sweat: Diffusion of excess urea, salts, and water.

7. How Do the Lungs function in Excretion?
By removing Carbon Dioxide from the body
HOW?
Explain the process

8. How Does the liver function in Excretion?
Liver DETOXIFIES THE BLOOD

9. How Does the Skin function in Excretion?
Sweat is excreted through tiny openings called pores.

10. SWEAT GLANDS
There are approximately 2 million sweat glands all over the skin.
They are tiny, coil shaped tubes.
They extend from the deepest layer of the skin to the surface.
These glands help to regulate the body temperature and also contribute to the excretion of water and salt from the body.
Sweat contains about 98-99% of water.
Certain inorganic salts – specially sodium chloride along with small make up the remaining 1-2%.

11. SKIN STRUCTURE

12. SWEAT GLAND

13. How do the Kidneys function in Excretion?
FILTER the blood
Kidneys are part of the Urinary System
Functional unit of Kidneys is the Nephron.

14. Kidneys and the urinary system including Nephrons

15. URINARY SYSTEM

16. URINARY SYSTEM

17. KIDNEY

19. The Glomerulus is a ball of capillaries found inside Bowmans Capsule.
The blood is filtered in Bowmans Capsule.
The Filtrate moves down into the loop of Henle where the reabsorption of some substances occurs.
Whatever is not reabsorbed is now urine and goes to a collecting tubule.
Collecting tubules empty into the ureters which lead to the bladder.
Urine exits through the urethra.

22. URETERS
There are 2 muscular tubes, 25 to 30 cm in length, with a very small inner diameter of about 3 mm.
They convey urine from the kidneys to the bladder.

23. URINARY BLADDER Pear shaped organ, which lies in the pelvis.
Though the 2 ureters, the bladder receives waste products, including urea from the kidneys.
The average capacity of the bladder is up to 400 or 500 mL.
The need to pass urine is usually felt when the bladder is filled to about 280 mL.
Sometimes up to 500 mL can be tolerated.
Filling above 500 mL leads to pain.

24. URETHRA
Is a passage way through which urine is discharged from the bladder.
In men the urethra is longer than in females.
It passes through the penis, and also has a passage for the discharge of semen.
In women the shorter urethra opens immediately in front of the vagina.
It serves solely for the discharge of urine.

25. URINE The average daily output of urine is 1.0 to 1.5 liters/day.
Apart from excess water, urine contains nitrogenous substances (chiefly urea) – approximately 32 g and mineral salts containing sodium, chloride, phosphorus, and potassium.
Urea and other nitrogen containing substances are derived from protein.
These compounds undergo further changes in the liver before passing to the kidneys to be excreted in the urine.