Download The Excretory System

The Excretory System
Name: __________________________________________ Date: ____________
Can you imagine a city without sewers, chimneys, or garbage removal? Waste materials would
pile up and up. Before long, everyone would have to move. Nobody could live there.
Your body must get rid of wastes, too. You cannot live without getting rid of waste products.
The body makes several kinds of waste materials. There are two main groups, undigested solid
wastes and wastes made by the cells.
You have already learned that undigested solid wastes leave the body through the large
intestine and anus. This process is called elimination.
The cells make many different wastes. These wastes include water, heat, carbon dioxide, salts
and urea. The removal of the waste products made by the cells is called excretion. In excretion, the
blood picks up the wastes from the cells. The wastes are sent to specialized organs that pass them out
of the body.
The main organs of excretion are the lungs, kidneys and skin. Together, these make up the
excretory system.
LUNGS. You have already learned that the lungs excrete carbon dioxide, water and heat.
SKIN. The skin excretes most of the body’s waste heat. In addition, the skin removes some
water, salts, and a very small amount of urea. These wastes are excreted by the skin as sweat or
perspiration.
KIDNEYS. The kidneys excrete a liquid waste called urine. Urine is a mixture. It is made up
mainly of water and urea. But it also contains some salts. Some heat is also excreted from the body
by the kidneys.
LIQUID WASTES
Liquid wastes follow a path out of your body, just like the solid wastes. The liquid wastes are
filtered from your bloodstream in
your kidneys. They then pass
through a long, thin tube called the
ureter to your bladder. This organ
holds the urine until it is allowed to
Artery
Vein
Right Kidney
Left Kidney
Ureter
leave. When your bladder is full,
a message is sent to your brain.
You open a small muscle at the
bottom of your bladder, and urine
leaves your body through the
urethra.
Bladder
Urethra
Name: ________________________________________
Date: ______________________
Excretory System Review
Label the parts of the excretory system
Word Bank
Bladder
Kidneys
Lungs
Skin
Ureter
Urethra
Complete the chart by putting an “X” in the correct boxes
Function
Excretory Organs
Kidneys
Lungs
Skin
Bladder
Removes water
Brings oxygen to the blood
Removes salt
Stores urine
Removes carbon dioxide
Produces urine
Removes body heat
1) Which are the organs of excretion? _________________________________________________
______________________________________________________________________________
______________________________________________________________________________
2) List 5 wastes that the body must excrete. ____________________________________________
______________________________________________________________________________
______________________________________________________________________________
3) Which of these wastes is only excreted by the lungs? __________________________________
______________________________________________________________________________
4) What other wastes do the lungs help excrete? ________________________________________
______________________________________________________________________________
5) The kidneys excrete a liquid mixture called urine. What are the two main waste products of urine?
______________________________________________________________________________
______________________________________________________________________________
6) What other two waste products are found in urine? ____________________________________
______________________________________________________________________________
7) What is the main waste excreted by the skin? _________________________________________
______________________________________________________________________________
8) What other waste products does the skin excrete? ____________________________________
______________________________________________________________________________
The Kidney System
Label the diagram using the word bank.
A.
Word Bank
Artery
F.
Bladder
B.
Kidneys
E.
Ureter
Urethra
Vein
D.
Each part of the kidney system is described
C.
below. Try
to identify each part from its description. Write the letter of each part on the line next to the
description.
9) ___________ Shaped like kidney beans. The kidneys make urine.
10) ___________ Urine leaves the kidneys through these tubes. There are two– one for each kidney.
11) ___________ A sac that collects and stores urine.
12) ___________ A tube that carries urine from the bladder to the outside of the body. There is one.
13) ___________ Carry blood to and from the kidneys. (Hint: You will have two letters for this
question.)
14) How are wastes from the cells carried to the kidneys? ___________________________________
_______________________________________________________________________________
The Skin System
The skin has many different things inside of it.
A gland is shown at right.
15) What is this gland called? ______________
____________________________________
____________________________________
16) Name the liquid mixture excreted by this
gland. ______________________________
____________________________________
____________________________________
17) List the four wastes that are excreted by the
skin.
____________________________________
____________________________________________________________________________
18) Name the two main wastes excreted by the skin. ____________________________________
_____________________________________________________________________________
Think About It!
Your body makes more waste products when it is working harder, when you are very active. Your
brain sends messages to your respiratory system, your circulatory system and your skin system to help
eliminate the wastes. How do each of these systems change to help eliminate wastes?
1. Respiratory system changes by ______________________________
2. Which wastes are eliminated? ___________________________________
3. Circulatory system changes by ______________________________
4. Which wastes are eliminated? ___________________________________
5. Skin system changes by ____________________________________
6. Which wastes are eliminated? ___________________________________
7. Evaporation cools the skin because: _________________________________________