Chapter 1
Lesson 4
What does the digestive system do?
• It breaks down food into materials
the body can use.
Which organ system is most
important?
• ALL the organ systems are
needed for the animal to
survive.
Look and Wonder p. 60
• What makes a macaw’s wings move?
• Muscles make the wings move.
Let’s read pgs. 62-63.
• What are two functions of
the skeletal system?
• Protection and Support
What animals have skeletons on the
outside of their bodies?
•Arthropods
Look at the illustrations on pgs. 62-63.
• Why does the rabbit need opposing muscles in
order to run?
• One muscle pulls the leg up and the opposing
muscle pulls the leg down.
• What type of tissue attaches
muscle to bone?
• tendons
Quick Check Questions p. 63. Partners discuss
the answers to these questions (3 min.).
• Tell what happens to the rabbits muscles as it
runs.
• A nerve signal arrives at the muscle and
causes the muscle to contract. The contracted
muscle pulls on the tendon, which pulls the
leg bone up. Another muscle, which pulls
down, relaxes. This cycle of contracting and
relaxing continues as the rabbit runs.
Muscles that move your fingers are in your
arm. How are your fingers able to move?
• The muscles are connected to the
bones by the tendons.
Let’s read
pgs. 64-65.
Digestion
• Food has nutrients that cells need to stay alive
but the body must break down the food to
release the nutrients.
What body parts does food pass
through?
•
•
•
•
Mouth
Esophagus
Stomach
Intestines
What body parts make chemicals that
digest food?
mouth, stomach, liver, and pancreas
Read a diagram p. 64.
• What digestive organs do worms and humans
have in common?
• Mouth, esophagus, and intestines
What are three ways humans remove
wastes?
• Humans remove excess water, salt, and other
wastes by sweating, humans breathe out
carbon dioxide, and remove excess water and
collected wastes from the kidneys as urine.
What do the kidneys do?
• They filter wastes from the
blood to produce urine.
Quick Check Questions p. 65
• What key steps take place in the process of
digestions?
• Chewing in the mouth, chemical breakdown in
the stomach, further chemical breakdown in
the small intestine and absorption into the
bloodstream, and reabsorption of water and
removal of undigested waste matter in the
large intestine.
Why are nephrons surrounded by
many tiny blood vessels?
• Nephrons have a membrane that allows some
substances to flow in and out. Waste products
are collected by the nephrons, and useful
substances such as nutrients are passed to the
blood through blood vessels.
Let’s read pgs. 66-67.
What is the main respiratory organ
in a mammal?
The lungs
How are the bronchi related to
the alveoli?
The bronchi are small tubes
that empty into thin-walled air sacs
called alveoli.
Could the lungs supply oxygen to your body cells
without the circulatory system?
• No
• Why?
• The lungs need a way to transport the oxygen
to other parts of the body.
Look at the illustration of the heart
and lungs on p. 66.
• Let’s name the parts of each organ.
• What is the main function of the
lungs?
• The main function of the lungs is to
exchange oxygen and carbon dioxide
with the blood.
Read a diagram p. 67.
• Where is the oxygen-poor blood
pumped?
• Oxygen-poor blood is pumped to the
lungs where the blood picks up
oxygen and rids itself of carbon
dioxide.
Quick Check Questions p. 67.
• What steps does the circulatory system take to
deliver blood to the body?
• The heart pumps oxygen-rich blood to the
body cells. Blood vessels return carbon
dioxide-rich blood to the heart and then the
lungs, where the blood picks up oxygen and
gets rid of carbon dioxide. The oxygen-rich
blood returns to the heart and is pumped back
to the body cells.
Is the respiratory system part of the
excretory system? Explain.
• The respiratory system is part of the
excretory system because it removes
carbon dioxide from the body.
Carbon dioxide is a cellular waste
product.
Let’s read p. 68.
• Animals sense and respond to their
surroundings.
• What is a stimulus?
• Anything in the environment that bring about
responses from the body.
• What body systems work together to respond
to stimuli?
• The nervous system, the skeletal system, and
the muscular system
Look at the illustration of the nervous
system on p. 68.
• What is the function of the three types of
neurons?
• Sensory neurons receive stimuli from the
body.
• Motor neurons carry messages from the brain
and spinal cord to the body’s organs and
glands.
• Associative neurons connect the sensory
neurons to the motor neurons.
Quick Check Questions p. 68.
• What is the function of the nervous system?
• The nervous system works with other body
systems to help organisms respond to stimuli
in their environment as well as stimuli inside
their body.
How does the nervous system work
closely with other body systems?
• The nervous system works with the muscular
system to help move the body. Messages sent
through the nervous system signal muscles to
contract.
Choose the BEST answer for each
question.
Which happens first when an
animal moves its leg?
Which part of the digestive
system absorbs nutrients?
• A. A muscle contracts.
• B. The tendon pulls on a
bone.
• C. The muscle pulls on a
tendon.
• D. A nerve impulse reaches
a muscle.
•
•
•
•
A.
B.
C.
D.
Mouth
Stomach
Esophagus
Small intestine
Choose the BEST answer for each
question.
Which structure in fish performs the
same function as lungs in mammals?
Which animal has an open
circulatory system?
•
•
•
•
•
•
•
•
A.
B.
C.
D.
Fins
Gills
Veins
Swim bladder
A.
B.
C.
D.
Lobster
Sparrow
Rattlesnake
Timber wolf
How might an animal’s damaged
sensory neurons affect its safety?
• An animal with damaged sensory neurons
would not be able to properly receive
messages about its body and its environment.
If danger were nearby, the animal would likely
not be able to detect it and could get hurt or
killed.