Download Lesson 3: How do organs work together?

Name
Lesson 3 Summary
Use with pp. 46–49
Lesson 3: How do organs work together?
Vocabulary
organ system a group of organs and tissues that work together to carry
out a life process
Organ Systems
Organ Systems Work Together
Cells work together in tissues. Tissues
work together in organs. Organs work
together as part of an organ system. For
example, the mouth, stomach, intestines,
and other organs work together to digest
food.
The muscle and skeletal systems work
together to move your body. Muscles work
in pairs to move bones.
Try this. Hold your arm out straight in
front of you. Bend your elbow. The muscle
on the bottom of your arm relaxes. The
muscle on top of your upper arm tightens.
This pulls on the bone of your upper arm
and makes your elbow bend. The opposite
happens when you stretch your arm. The
bottom of your upper arm tightens. The top
of your arm relaxes.
Bones Form a System
Each bone is an organ. There are about
200 bones in the skeletal system. This
organ system gives your body support. The
skeletal system also protects important
organs. The skull is made of bones that
protect your brain. The rib cage is made of
bones that protect your lungs and heart.
Muscles Work as a System
Your organ systems work together too.
For example, your nervous system controls
how your muscles move bones. Nerves
carry signals from your brain and spinal
cord to your muscles. Without nerves, your
muscles would never move.
Some organs work for more than one
organ system. For example, muscles don’t
just work with bones. Muscles in your heart
push blood through your blood vessels.
© Pearson Education, Inc. 5
Muscles are organs. They work together
to move your body. There are about
640 muscles that you control. When you
run, your brain tells your muscles how
to work together. Other muscles work by
themselves. When you shiver, muscles work
to warm the body. You do not have to think
about shivering. It happens without your
thinking about it.
Other Systems Work Together
14
Chapter 2, Lesson 3 Summary
Quick Study
Name
Lesson 3 Checkpoint
Use with pp. 46–49
Lesson 3 Checkpoint
1. How many bones make up the skeletal system?
2. List some organ systems and describe their jobs.
© Pearson Education, Inc. 5
3. How do muscles work in pairs to move a bone?
Quick Study
Chapter 2, Lesson 3 Checkpoint
15