Human Body [Muscular System]

The Muscular System

Key Concepts

- What types of muscles are found in the body?

- Why do skeletal muscles work in pairs?

Vocabulary Words
- involuntary muscle
- voluntary muscle
- skeletal muscle
- tendon
- striated muscle
- smooth muscle
- cardiac muscle

Science Activity

How Do Muscles Work?

1. Grip a spring-type object with the thumb and index finger of your writing hand. Squeeze the object open and shut as quickly as possible for two minutes. Count how many times you can squeeze the object before your muscles tire.

2. Rest for one minute. Then, repeat Step 1.

Open Ended

What do you think would happen if you repeated Steps 1 and 2 with your other hand? Give a reason for your prediction. Then, test your prediction.

Click the Link to Watch the Video

Video About the Muscular System

When you are finished, close the video and continue to the next slide.

Muscles that are under your conscious control. Smiling, turning a page in a book, or getting out of your chair are all controlled by voluntary muscles.

Voluntary Muscles

Muscles that are not under your conscious control. They are responsible for essential activities such as breathing and digesting food.

Involuntary Muscles

Types of Muscle

Multiple Choice

What are involuntary muscles?

• Muscles that are not under your conscious control

• Muscles that are under your conscious control

Multiple Choice

Smiling, turning a page in a book, and getting out of your chair are examples of using what kind of muscles?

• Involuntary Muscles

• Voluntary Muscles

Cardiac muscle is found only in the heart. This muscle is involuntary and does not get tired.

Cardiac Muscle

Skeletal muscles are attached to the bones of your skeleton and provide the force that moves your bones. This muscle is voluntary, but they get tired easily.

​​Skeletal Muscle

​Smooth muscles are located on the inside of many internal organs such as the stomach blood vessels. This muscle is involuntary and automatically controls movement.

​​Smooth Muscle

The tissue called cardiac muscle is found only in your heart. Cardiac muscle has some characteristics in common with both smooth muscle and skeletal muscle. Like smooth muscle, cardiac muscle is involuntary. Like skeletal muscle, cardiac muscle cells are striated. However, unlike skeletal muscle, cardiac muscle does not get tired. It can contract repeatedly. The repeated contractions are called heartbeats.

Cardiac Muscle

striated muscle - muscle tissue that appears striped or banded.

Every time you walk across the room, you are using skeletal muscles. Skeletal muscles are attached to the bones of your skeleton and provide the force that moves your bones. At each end of the skeletal muscle is a tendon. A tendon is a strong connective tissue that attaches muscle to bone.

Because you have conscious control of skeletal muscles, they are voluntary muscles. Skeletal muscles react very quickly. However, they also get tired quickly.

Skeletal Muscle

The inside of many internal organs, such as the stomach and blood vessels, contain smooth muscles. Smooth muscles are involuntary muscles. They work automatically to control certain movements inside your body, such as those involved in digestion. For example, as the smooth muscle of your stomach contract, they produce a churning action. The churning mixes the food with chemicals, and helps to digest the food.

Unlike skeletal muscles, smooth muscles are not striated. Smooth muscles react slowly and do not tire as quickly.

Smooth Muscle

Multiple Choice

What muscle is found only in the heart?

• Smooth Muscle

• Skeletal Muscle

• Cardiac Muscle

Multiple Choice

What muscle is attached to the bones of your skeleton?

• Skeletal Muscle

• Cardiac Muscle

• Smooth Muscle

Multiple Choice

What muscle is found inside many of your internal organs, such as the stomach?

• Cardiac Muscle

• Skeletal Muscle

• Smooth Muscle

Click the Link to Watch the Video

Video About Tendons

When you are finished, close the video and continue to the next slide.

Tendons are strong connective tissues that attach muscle to bone.

Tendons

Ligaments are strong connective tissues that attach bone to bone

Ligaments

Multiple Choice

Which strong connective tissue connects muscle to bone?

• Ligament

• Tendon

Multiple Choice

Which strong connective tissue connects bone to bone?

• Ligament

• Tendon

Has anyone ever asked you to "make a muscle"? If so, you probably tightened your fist, bent your arm at the elbow, and made the muscles in your upper arm bulge. Like other skeletal muscles, the muscles in your arm do their work by contracting, becoming shorter and thicker. Muscle cells contract when they receive messages from the nervous system.

Muscles at Work

Because muscle cells can only contract, not extend, skeletal muscles must work in pairs. While one muscle contracts, the other muscle in the pair relaxes to its original length.

Regular exercise is important for maintaining both muscular strength and flexibility. Exercise makes individual muscle cells grow in size. As a result, the whole muscle becomes thicker. The thicker a muscle is, the stronger the muscle is. When you warm up thoroughly before exercising, the blood flow to your muscles increases and they become more flexible. Stretching after you warm up helps prepare your muscles for more vigorous exercise or play ahead.

Muscular Strength and Flexibility

When you warm up before exercising, you increase the flexibility of your muscles.

Skills Lab

Refer to the worksheet and complete the questions attached. Once finished, move on to the next slide.

You have finished this lesson.

GREAT JOB!!!