The Muscular System YOUR 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.

Muscles Muscle 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 Muscles  Muscles 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/brain  Ex. 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) Skeletal  Also called striated muscles  These muscles are attached to the skeleton for movement.  Can be voluntary or involuntary  Ex. 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