1.2 The Skeletal System The ankle bone’s connected to the… shin bone… the shin bone’s connected to the knee bone…

The Skeletal System Primary Function –Support and protect the body –Allow the body to move Made of –Bones –Cartilage –Connective tissue that holds bones together »**Ligaments (bone to bone) »** Tendons (muscle to bone)

Bone Growth Most bone starts off as a flexible tissue called cartilage Born with cartilage, but as you grow the cartilage is replaced by bone During childhood, most bones still have growth plates of cartilage –Growth plates provide a place for bones to continue to grow End of your nose and the top of your ear are 2 places where cartilage is never replaced by bone

Bones Average adult has 206 bones Support & protect parts of your body Work with muscles so you can move Help your body maintain homeostasis by storing minerals and making blood cells

Bones Functions of skeleton –Protection Heart and lungs protected by ribs Spinal cord is protected by vertebrae Brain protected by skull –Storage Bones store minerals that help your nerves and muscles function properly Long bones store fat that can be used for energy –Movement Skeletal muscles pull on bones to produce movement –Blood Cell Formation Some bones are filled with marrow that makes blood cells

Bone Structure Living organs made of connective tissue and minerals –Minerals deposited by living cells called osteoblasts 2 types of bone tissue –Compact bone No visible open spaces Rigid and dense Tiny canals in bone contain small blood vessels –Spongy Bone Many open spaces Provides much of the strength and support for a bone

Bone Structure Bones contain a soft tissue called marrow 2 types –Red marrow: produces both red and white blood cells –Yellow marrow: stores fat Found in the central cavity of long bones

Joints A place where 2 or more bones meet Allow your body to move when your muscles contract Can be classified based on how the bones in a joint move Held together by ligaments –Strong elastic bands of connective tissue –Connect the bones in a joint Cartilage covers the ends of bones & helps cushion the area in a joint where bones meet

Joints Examples Gliding joint: allow bones in the hand and wrist to glide over one another and give flexibility Ball-and-socket joint: like a video game joystick; allows shoulder to move freely in all directions Hinge joint: like a hinge allows a door to open and close, the knee enables you to flex and extend your lower leg

Skeletal System Injuries Bones can be fractured (broken) Sprain: a ligament is stretched too far or torn A dislocated joint: a joint in which one or more bones have been moved out of place

Skeletal System Diseases Diseases of the skeletal system –Osteoporosis Causes bones to become less dense Bones become weak and break more easily Age and poor eating habits can increase the likelihood that it will occur –Arthritis Affects the joints Painful Joints swell or stiffen