Skeletal SystemSkeletal SystemChapter 45.2Chapter 45.2

The SkeletonThe Skeleton

Main functions: rigid framework for support, Main functions: rigid framework for support, protection, allowing bodily movement, producing protection, allowing bodily movement, producing blood, and storing minerals. blood, and storing minerals.

Contains approx. 206 bones.Contains approx. 206 bones.

The human skeleton is divided into two parts:The human skeleton is divided into two parts:

1. axial (skull, ribs, spine, sternum)1. axial (skull, ribs, spine, sternum)

2. appendicular (everything else)2. appendicular (everything else)

Bones StructureBones Structure

Periosteum --- Membrane that contains a network Periosteum --- Membrane that contains a network of blood vessels which supplies nutrients. (Outer of blood vessels which supplies nutrients. (Outer layer of the bone.)layer of the bone.)

Compact bone --- Allows the bone to endure a Compact bone --- Allows the bone to endure a large amount of stress it receives upon impact.large amount of stress it receives upon impact.

Spongy Bone - Network of connective tissue.Spongy Bone - Network of connective tissue.

Haversian canal: Narrow channel that Haversian canal: Narrow channel that blood vessels run through that carries blood vessels run through that carries nourishment to living bone tissuenourishment to living bone tissue

Osteocytes: Bone cells Osteocytes: Bone cells Osteoclasts: Bone cell that removes bone Osteoclasts: Bone cell that removes bone

tissuetissue Osteoblasts: Bone cells responsible for Osteoblasts: Bone cells responsible for

bone formationbone formation

Bone Marrow --- Red or YellowBone Marrow --- Red or Yellow Red Marrow --- Produces red blood cells & Red Marrow --- Produces red blood cells &

certain types of white blood cells.certain types of white blood cells. Yellow Marrow --- Consists of fat cells & Yellow Marrow --- Consists of fat cells &

serves as energy storage.serves as energy storage.

Bone DevelopmentBone Development

Bone develops from Bone develops from cartilage.cartilage.

Cartilage is a tough, flexible connective Cartilage is a tough, flexible connective tissue.tissue.

Cartilage will eventually harden during Cartilage will eventually harden during fetal development in a process called fetal development in a process called ossification.ossification.

Epiphyseal Plate: Place near the ends of Epiphyseal Plate: Place near the ends of long bones where elongation occurslong bones where elongation occurs

JointsJoints

JointsJoints are places where two bones meet. are places where two bones meet.

Joints are held together by Joints are held together by ligamentsligaments, tough , tough bands of connective tissue.bands of connective tissue.

Because of all the movement and friction of Because of all the movement and friction of joints, joints, synovial fluidsynovial fluid helps protect the ends helps protect the ends of bones.of bones.

Hinge JointHinge Joint

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

Gliding JointGliding Joint

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

Pivot JointPivot Joint

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

Ball & Socket JointBall & Socket Joint

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

Saddle JointSaddle Joint

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

Skeletal System DisordersSkeletal System Disorders Inflammation: Protective attempt by the body to Inflammation: Protective attempt by the body to

remove the injurious stimuliremove the injurious stimuli Arthritis: Disorders that cause painful, swollen Arthritis: Disorders that cause painful, swollen

jointsjoints Rheumatoid Arthritis: develops when immune Rheumatoid Arthritis: develops when immune

system begins to attack body tissues.system begins to attack body tissues. Osteoarthritis: a degenerative joint disease Osteoarthritis: a degenerative joint disease

where cartilage covering the surface of bone where cartilage covering the surface of bone becomes thinner and rougher.becomes thinner and rougher.

Osteoporosis: Thinning of bone tissue & loss of Osteoporosis: Thinning of bone tissue & loss of bone density over time.bone density over time.