Skeletal System Chapter 45.2

The Skeleton Main functions: rigid framework for support, protection, allowing bodily movement, producing blood, and storing minerals. Contains approx. 206 bones. The human skeleton is divided into two parts: 1. axial (skull, ribs, spine, sternum) 2. appendicular (everything else)

Bones Structure Periosteum --- Membrane that contains a network of blood vessels which supplies nutrients. (Outer layer of the bone.) Compact bone --- Allows the bone to endure a large amount of stress it receives upon impact. Spongy Bone - Network of connective tissue.

Haversian canal: Narrow channel that blood vessels run through that carries nourishment to living bone tissue Osteocytes: Bone cells Osteoclasts: Bone cell that removes bone tissue Osteoblasts: Bone cells responsible for bone formation

Bone Marrow --- Red or Yellow Red Marrow --- Produces red blood cells & certain types of white blood cells. Yellow Marrow --- Consists of fat cells & serves as energy storage.

Bone Development Bone develops from cartilage. Cartilage is a tough, flexible connective tissue. Cartilage will eventually harden during fetal development in a process called ossification. Epiphyseal Plate: Place near the ends of long bones where elongation occurs

Joints Joints are places where two bones meet. Joints are held together by ligaments, tough bands of connective tissue. Because of all the movement and friction of joints, synovial fluid helps protect the ends of bones.

Hinge Joint Found in your elbow. Allows you to move arm forward & backward. Like a door.

Gliding Joint Allows bones to slide over one another. Example are the joints between the small bones of your feet. Allows your foot to flex when you walk.

Pivot Joint Forms the top 2 vertebrae in your neck. Allows you to move your head side to side. (Saying “no”).

Ball & Socket Joint Found in your shoulder or hip. Allows you to move your arm up & down, forward & backward, & rotate in a complete circle.

Saddle Joint Found at the base of each thumb, allows you to rotate your thumbs and helps you grasp objects with your hand.

Skeletal System Disorders Inflammation: Protective attempt by the body to remove the injurious stimuli Arthritis: Disorders that cause painful, swollen joints Rheumatoid Arthritis: develops when immune system begins to attack body tissues. Osteoarthritis: a degenerative joint disease where cartilage covering the surface of bone becomes thinner and rougher. Osteoporosis: Thinning of bone tissue & loss of bone density over time.