Chapter 14: Bones, Muscles, and Skin

Section 3: The Muscular System

p. 482 – p. 486

What types of muscles are found in the human body?

• Your body has three types of muscle tissue – skeletal muscle, smooth muscle and cardiac muscle.

• Some of these muscle tissues are voluntary and some are involuntary.– Skeletal or striated muscle are voluntary

muscles.– Cardiac muscles are involuntary muscles.– Smooth muscles are involuntary muscles.

Why do skeletal muscles work in pairs?

• Skeletal muscles must work in pairs because they can only contract. While one muscle contracts the partner muscle relaxes or extends to its original length.

Involuntary Muscle

• Muscles that are not under your conscious control.

• They are responsible for such important activities as breathing, heartbeat, an digesting food.

• Examples are smooth and cardiac muscles.

Voluntary Muscles

• Muscles that are under your conscious control, like smiling or turning a page in your book.

Skeletal Muscles

• Are voluntary muscles that are attached to the bones of your skeleton and provide the force that moves your bones.

Tendon

• A strong connective tissue that attaches muscles to bone.

Striated Muscle

• Skeletal muscle cells appear to be banded, or striated. For this reason, skeletal muscle is sometimes called striated muscle.

Smooth Muscle

• The muscles that are inside of many internal organs, such as the stomach and blood vessels.

• They work automatically to control certain movements in your body.

• They are involuntary, which means you have no control of them.

Cardiac Muscle

• Cardiac muscle tissue is found only in the heart.

• It is involuntary. • Cardiac muscle

tissue is also is also striated. Yet it does not ever get tired like skeletal muscle tissue does.

Muscle 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.

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