The Muscular System

1. The Muscular System Your Muscles

2. 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.

3. 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.

4. 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.

5. 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.

6. Muscle Pairs

7. 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)

8. 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

9. 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.

10. 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

11. Three Types of Muscle: (2) Cardiac • An involuntary muscle found in your heart • Appear striated or skeletal in nature

12. Three Types of Muscle: (3) Skeletal • Alsocalled 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

13. 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.

14. 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.

15. 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.

16. Lesson Review Questions: 1 What happens to a muscles when it contracts? • It becomes stronger • It becomes shorter • It becomes longer • It bends

17. Lesson Review Questions: 2 What kind of muscles line blood vessels and many organs? • Smooth Muscles • Voluntary Muscles • Cardiac Muscles • Skeletal Muscles

18. Lesson Review Questions: 3 What is the term used to describe muscles that you can consciously control? • Skeletal • Involuntary • Cardiac • Voluntary