MUSCULAR SYSTEM*There are 206bones in the body* There areapproximately 640skeletal muscles in thebody.
*Three Types of Muscle *Muscles are classified according to their structure and function.
*SMOOTH MUSCLE*Involuntary Muscle*Muscle of the internal organs:(stomach, intestines, etc.)*Not striated, or striped, 1 nucleus
*CARDIAC MUSCLE*Involuntary*Only in the heart muscle*Contracts efficiently andrhythmically*Striped or Striated, with lightand dark bands and many nuclei
*SKELETAL MUSCLE*Voluntary Muscle*Attached to bones by tendons*When contracted, cause the body to move
Skeletal Muscle Contraction *Most skeletal muscles are arranged in opposing, or antagonistic pairs.
*TWO TYPES OF MUSCLE FIBERS: Slow- Fast- twitch twitch
*Slow-twitch muscle fibers *Slow-twitch muscle fibers have more endurance than fast-twitch muscle fibers. They contain myoglobin, a respiratory molecule that stores oxygen and serves as an oxygen reserve.
Fast-Twitch Muscle Fibers *Fast-twitch muscle fibers fatigue easily but provide great strength for rapid, short movements. They rely on anaerobic metabolism, which causes a buildup of lactic acid.
ENERGY FOR MUSCLES*Muscle cells need energy to contract*Muscle cells use cellular respiration to make ATP (adenosine triphosphate)* ATP = Energy (aerobic)*If enough oxygen is not available, muscleswill rely on lactic acid fermentation for energy.(anaerobic)
WHEN SOMETHING GOES WRONG…Muscular Dystrophy- • An inherited disease that affects the skeletal muscles in the body. • Eventually, the muscles are destroyed and the person may become paralyzed.
REVIEW QUESTIONS: W R I T E O N A S E PA R A T E PA P E R T O T U R N I N :1. Compare and Contrast skeletal, smooth and cardiac muscle.2. Explain why it is important for skeletal muscles to be foundantagonistic (opposite) pairs.3. Explain why it is important that no muscle contains only slow-twitch or only fast-twitch fibers.4. When does a muscle require ATP?5. Related to #4: Why does your body use energy even when youare sleeping?