1. Excretory System
LESSON 7

2. AIM: How does the body filter the blood to keep it free of waste?
Do Now:
Write heading and AIM in notebooks. Think about questions below and write answers in full sentences in your notebooks.
#1. Why is it important to take the trash out when it gets full?
#2. What happens if you do not take it out?

3. Excretory System: Functions
Eliminates body wastes
If not eliminated, wastes build up
Can lead to illness or death
Your body also needs to remove the wastes that build up from cell activity and from digestion. These wastes include carbon dioxide, urea, and certain plant materials. If these wastes are not removed, your cells can stop working and you can get very sick.

4. Urinary System (part of Excretory System)
Rids blood of wastes
Controls blood volume by removing extra water

5. Why is this important?
Fluid levels in body must be balanced (homeostasis)
Brain sends message to kidneys to either hold onto or get rid of water.
If you have too much water in your body, your cells can swell and burst. If you have too little water in your body, your cells can shrivel up like an old apple. Either extreme can cause illness and death of cells, tissues and organs. The organs of your excretory system help to keep the correct balance of water and salts in your body.

6. Mid Assessment
How does the Urinary System work to maintain homeostasis within the body?
What does it mean when your urine is very yellow?
Write answers on the board

7. Organs in Urinary System
Main organ: Kidneys
Bean-shaped
In your back

8. Urinary Pathway
Kidneys-> ureter-> urinary bladder-> urethra VIDEO

9. Kidney Functions Filters blood
Regulates amount of water and other substances in blood.
Remove wastes in Urine.

10. Kidneys cont. Filled with tiny filters called Nephrons.
Over 1 million nephrons in each kidney

11. Kidneys

12. Collection and Release
Once the water and blood has been filtered, the rest of the waste is collected in the kidneys.
Ureter – tubes that lead from kidney to the bladder

13. Collection cont.
Bladder – stretchable container that stores urine until it leaves body.
Can hold up to .5 liters of water
Similar to an inflated balloon
Urethra - channel for urine to flow out of the body
Question: What other organ is similar to the bladder; expands and shrinks depending on how much it is filled?
Answer: The Stomach

14. Homework: Critical Thinking Questions Online
The walls of the urinary bladder are stretchy. What do you think is the advantage of having these stretchy walls?
If a person's urine is dark brown, what are two organs in the body that might not be functioning properly? Explain what might be wrong with the two organs.

15. Diseases Waste products not removed build up and act like poison
Too much water in the body can lead to swollen body parts (ankles) or fluid build up around organs
Imbalance of salt. Body will try to restore this balance but if it can’t organs can be damaged.

16. Diseases cont. A person can live without a kidney and survive.
Remaining kidney makes up for the loss
If both fail, person needs blood filtered artificially with - Dialysis