The Skeletal System Structures and Functions

FUNCTIONS Support: Provides a framework for the body Support for soft tissues and a point of attachment for muscles

Protection From injury by skeleton Ex: skull protects brain vertebrae protects spinal cord Rib cage protects heart & lungs Pelvic bones protect reproductive organs

Movement Facilitation Bones serve as levers to which muscles are attached, when muscles contract movable joints acting as fulcrums cause movement

Storage Calcium & Phosphorus: essential for many homeostatic balances Blood Cells: red marrow stores and produces RBC’s, some white blood cells, and platelets (hematopoesis) Energy: yellow marrow stores lipids for chemical energy

Hematopoiesis “heme” meaning “blood” “poiesis” meaning “to make” Done in the Red marrow.

Types of Bones Long Bones: ex: humerus Short: ex: carpals Flat: ex: frontal Irregular: ex: vertebrae

Structure of Long Bones Diaphysis: bone shaft Medullary Canal: hollow area inside bone, contains marrow Epiphysis: ends of bone Articular Cartilage: covers the epiphysis Periosteum: fibrous covering, except at joints Endosteum: thin membrane lines the medullary canal

Spongy vs. Compact Spongy: contains a network of needle like threads of bone tissue that is surrounded by marrow. This network is called “trabeculae” Compact: outer layer, hard and dense, contains “osteons” (Haversian Systems) which are concentric circles of hard bone tissue

Cartilage Made up of cells called “ chondrocytes” Lacks blood vessels, so nutrients must diffuse through the matrix of gel to reach the cells

Bone Formation & Growth In utero: skeletal tissue is made up of cartilage and fibrous material, so… Baby’s bones are cartilage until calcification occurs,. By birth, many of the long bones,skull bones, and bones of the hands and feet are calcified.

“Remodeling” Replacing of cartilage with calcified bone matrix. Osteoblasts: bone forming cells that do the work of remodeling. Osteoclasts: bone resorbing cells. Combined action of these 2 cells allows the sculpting of bones.

Divisions of Skeleton Axial Skeleton: bones of the center or axis of the body: ex: Cranium, Spine, Thoracic bones, Hyoid Bone There are a total of 80 Axial Skeletal Bones

Divisions of Skeleton Appendicular: Bones of the upper and lower extremities or appendages Ex: Humerus, radius, ulna, carpals etc. Femur, Tibia, Fibula, tarsals etc. There are a total of 126 appendicular bones

Skull Consists of: Cranium: 8 bones Face: 14 bones Ear: 6 Sutures: immovable joints in the skull

Spine Vertebral Column: series of vertebrae 5 sections: Cervical, Thoracic, Lumbar, Sacrum, Coccyx Cervical: 7 vertebrae, 1 st cervical vertebrae is called the atlas, 2 nd cervical vertebrae is called the axis. Thoracic: 12 vertebrae Lumbar: 5 vertebrae Sacrum & Coccyx: 1 of each

Appendicular Skeleton HumerusRadiusUlna Carpals Metacarpals Phlanges Ilium Ishium Symphysis Pubis FemurPatellaTibia FibulaTarsalsMetatarsals Phlanges

Conclusion Study Skeletal System…Know sections of long bones and label skeletal bones