Muscular SystemSection 1.2

MusclesMuscles are an organ.

Can relax, contract, and provide the force to move your body parts.

Energy is used to move muscles.

Your body has more than 600 muscles.

No matter how still you might be, there are muscles that are still working. Which ones?

Muscles that you are able to control are called voluntary muscles.

Muscles that you cannot control are called involuntary muscles.

Do you have control?

Three Muscle

Types

Move bones

Most common muscle type

Attached to bones by thick bands of tissue called tendons

Appear striated and striped

Voluntary muscles

Contract quickly and tire more easily than involuntary muscles.

Skeletal Muscles

Found only in the heart

Muscle tissue has striations

Contracts about 70 times per minute, every day of your life

Cardiac Muscles

Human Heart

Found in intestines, bladder, blood vessels, and other internal organs

Non striated, involuntary muscles that slowly contracts and relaxes

Internal organs are made of one or more layers of smooth muscle

Smooth Muscles

You have the same number of muscles now as you did when you

were born.

But you knew that right??

Fun Fact

When one muscle pair contracts, the other muscle relaxes, or returns to its original length.

Muscles Work Togetherisn’t that nice!!

Muscles can become larger or smaller over time depending if they are used or not.

Muscles that are given regular exercise respond quickly to stimuli.

If muscles are not exercised they will become soft and flabby and will lack strength. They become smaller in size.

Muscles Can Change

Chemical energy is needed for muscle activity.

Chemical energy is supplied by food and is changed into mechanical energy (movement) and thermal energy (heat).

How Muscles Move