The Muscular SystemYOUR MUSCLES

Functions of the Muscular System

A muscle is made of strong tissue that can contract in an orderly way.

When a muscle contracts, the cells of the muscle become shorter.

When a muscle relaxes, the cells return to their original length.

Functions of the Muscular System (cont.)

Bones move when muscles contract.There are many muscles in your body that are

not attached to bones.The contraction of these muscles cause blood

and food to move throughout your body.Muscles that are attached to bones support

your body and help you balance.Muscles protect your body by covering most

of your skeleton and most of the organs inside your body like a layer of padding.

Functions of the Muscular System (cont.)

Shivering occurs when muscles contract rapidly and change chemical energy to thermal energy, thereby raising your body’s temperature.

Muscles also change chemical energy to thermal energy during exercise.

MusclesMuscle Attach to Bones Tendons are strands or tough

connective tissue that connect your skeletal muscles to your Bones.

Muscles Work in Pairs Skeletal muscles often work in

pairs. A muscle that bends part of your body is called a flexor. A muscle that straightens part of your body is an extensor.

Muscle Pairs

Muscle Pairs (cont.)

Bend Your Arm Bicep muscles-

contract (flexor) Tricep muscles-relax

(extensor)

Straighten Your Arm Bicep muscles-relax

(flexor) Tricep muscles-

contract (extensor)

Muscle Control: Voluntary MusclesMuscles that you are able to control

Ex. Arm and leg muscles, muscles of your hands and face

You can choose to move them or not

Muscle Control: Involuntary Muscles

Muscles that you can’t consciously control

These muscles work all day long, all your life.Ex. Blood gets pumped through blood

vessels, food is moved through the digestive system by the action of involuntary muscles.

Three Types of Muscle: (1) Smooth

Muscles found in the walls of many organs

Involuntary in action cannot be controlled by will/brainEx. Digestive system and blood

vessels

Three Types of Muscle: (2) Cardiac

An involuntary muscle found in your heart

Appear striated or skeletal in nature

Three Types of Muscle: (3) SkeletalAlso called striated muscles

These muscles are attached to the skeleton for movement.

Can be voluntary or involuntaryEx. Legs/arms are voluntary

Skeletal muscles work in pairs

Keeping Muscles Healthy Exercise helps keep muscles healthy. Muscle cells decrease

in size and strength without exercise. Resistance Exercise

During resistance exercise, people work against the resistance, or weight of an object to strengthen their skeletal muscles.

Aerobic Exercise (using oxygen)Steady, moderately intense activity is called aerobic

exercise and it strengthens the heart and increases endurance.

Muscle Injury

A strain is an injury when a muscles or tendon is overstretched or torn.

A sprain is when a ligament is stretched or torn from a joint.

People who exercise too much can hurt their tendons. Inflamed tendons is called tendonitis.

The Muscular System and Homeostasis

Muscle contractions convert chemical energy to thermal energy and keep your body warm.

When you exercise, the cardiac muscles of your heart help maintain homeostasis by contracting more often.

When it contracts faster, the heart pumps more blood and more oxygen is carried to the cells.

Lesson Review Questions: 1

What happens to a muscles when it contracts?

A. It becomes stronger

B. It becomes shorter

C. It becomes longer

D. It bends

Lesson Review Questions: 2

What kind of muscles line blood vessels and many organs?

A. Smooth Muscles

B. Voluntary Muscles

C. Cardiac Muscles

D. Skeletal Muscles

Lesson Review Questions: 3

What is the term used to describe muscles that you can consciously control?

A. Skeletal

B. Involuntary

C. Cardiac

D. Voluntary