Excretory SystemLESSON 7

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?

Excretory System: Functions

Eliminates body wastes If not eliminated, wastes build up Can lead to illness or death

Urinary System (part of Excretory System)

Rids blood of wastes Controls blood volume by removing

extra water

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.

Mid AssessmentHow does the Urinary System

work to maintain homeostasis within the body?

What does it mean when your urine is very yellow?

Organs in Urinary SystemMain organ:

Kidneys

Bean-shaped

In your back

Kidneys-> ureter-> urinary bladder-> urethraVIDEO

Urinary Pathway

1. Filters blood

2. Regulates amount of water and other substances in blood.

3. Remove wastes in Urine.

Kidney Functions

Kidneys cont.Filled with tiny filters called

Nephrons.

Over 1 million nephrons in each kidney

Kidneys

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

Collection cont.Bladder – stretchable container that

stores urine until it leaves body. Can hold up to .5 liters of waterSimilar 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

Homework: Critical Thinking Questions Online

1.The walls of the urinary bladder are stretchy. What do you think is the advantage of having these stretchy walls?

2.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.

DiseasesWaste 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.

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