Body Systems Bones and Muscles

Skeletal Systems 4 functions Key role in movement Provides a strong, stable, and mobile framework on which muscles can act Supports and protects internal organs Storage center for essential body materials (ex: calcium and phosphorous) Manufactures blood cells

Structure of Skeletal System 206 bones Axial skeleton 80 bones around the core of the body: examples: skull, spine, ribs, and sternum Appendicular skeleton 126 bones outside the core frame (appendicular - appendices) examples: shoulders, arms, hands, hips, legs, and feet

Types of Bones Four types of bones: Long - femur Short - wrist Flat - rib Irregular - vertebrae

Cartilage and Joints Cartilage: strong, flexible connective tissue (tip of your nose) Joints: the point at which two bones meet Ball and socket joint: shoulder Pivot joint: head and shoulders Ellipsoidal joint: wrist Hinge joint: elbow

Ligaments and tendons Ligaments Tough bands of fibrous, slightly elastic tissue that bind the bone ends at the joint Tendons Fibrous cord that join muscle to bone or to other muscles

Types of Muscles Cardiac Muscles: Special type of striated tissue that forms the walls of the heart Smooth Muscles: Concerned with internal movements of internal organs (involuntary, like intestines) Skeletal Muscles: Striped muscles (striated) that are attached to bones that cause body movements (voluntary) Flexors: muscles that close a joint Extendors: muscles that open out a joint

Muscles: Use it or lose it Atrophy: unused muscles waste away Muscle tone: the natural tension in the fibers of a muscle