1. MUSCULAR SYSTEM

3. Functions of the Muscular System Without muscles, nothing in your body would work All body movements depend on muscles Pump blood throughout your body Move food through your digestive system Control the movement of air in and out of your lungs

4. Muscle Facts There are over 600 muscles in the body 40% of your total weight is muscles Eyelids are the busiest muscles in the body The gluteus maximus is the largest muscle in the body There are 30 facial muscles

5. How Muscles Work Muscles work by means of two complementary-or opposing- actions These are contraction, the shortening of a muscle, and extension, the stretching of a muscle Muscle contraction is triggered by nerve impulses Muscles are only able to contract or pull Lactic acid is a waste produced when muscles contract

6. Structure of the Muscular System The basic unit of a muscle is muscle cell A muscle is composed of bundles of fibers and cells The major muscles in the body are made up of hundreds of bundles A muscle fiber is made up of even smaller units called myofibrils Each myofibril is in turn made up of microscopic filaments called actin and myosin, proteins that control muscle contraction. The two types of muscle fibers are slow and fast

7. Types of Muscles Your body has three basic types of muscle tissue: – Smooth muscle – Skeletal muscle – Cardiac Muscle

8. Smooth Muscles Are the type of muscle concerned with the movements of internal organs Found in the intestines, the bronchi of the lungs, the stomach, the bladder, and the walls of the blood vessels Also called involuntary muscles because they work without a person’s conscious control

9. Skeletal Muscles Are the striped, or striated, muscles attached to bones that cause body movements Form the largest part of the body’s muscular system More than 600 such muscles Are voluntary, under conscious control Two or more skeletal muscles may oppose each other’s actions While one contracts, the other relaxes Classified according to the type of action each muscle performs Muscles that close a joint are called flexors Muscles that open out a joint are called extensors

10. Cardiac Muscles A special type of striated tissue that forms the walls of the heart Your heart is the most important muscle in your body Its unique properties enable it to contract rhythmically about 100,000 times a day to pump blood throughout the body Involuntary muscle

11. Major Muscles Deltoids are the muscles in each shoulder, which help you move your shoulders every which way Pectoralis are found on each side of your upper chest Abdominals Triceps are the large, three headed muscles that form the back of the upper arm Biceps

12. Injury Related Muscular problems Muscle strain- a strain, or a “pulled muscle,” is a tearing or stretching of muscle fibers as a result of suddenly pulling them too far Muscle cramp is a sudden muscle contraction causing severe pain Bruise is a discolored area under the skin caused by leakage of blood after an injury Tendinitis is the inflammation of a tendon, usually caused by overuse. Achilles is the strongest tendon in the body