Functions and Structure of Bones

Ch. 6

Functions of bone

• Support• Protection• Movement• Mineral homeostasis• Blood cell production• Energy storage

Support

• Provide a framework for the body• Muscles attach to skeletal system

Protection

• Protects internal organs• Surrounds:– Ribs – heart, lungs, liver, spleen– Skull – brain– Vertebrae – spinal cord

Movement

• Muscles pull on bones to produce motion• Muscles contract

Storage and Production

• Produce red blood cells– Produced by red bone marrow– Process called: hemopoiesis

• Stores minerals– Calcium, phosphorus– Releases minerals into blood

stream as needed• Stores energy– Lipids stored in yellow bone

marrow

Structure of Bone• Best examined in long bones (femur, humerus,

tibia, fibular, radius, ulna)

Structure of bone

• Diaphysis – dī-AF-i-sis– dia = through– physis = growth– The shaft or long

portion of the bone

Structure of bone

• Epiphysis (e-PIF-i-sēz)– epi = above, physis = ?– The ends of the bone– Proximal and distal

Structure of bone

• Metaphysis (me-TAF-i-sis)– Where the diaphysis meets

the epiphysis– Includes epiphyseal plate

Structure of bone

• Articular cartilage– Thin layer of hyaline cartilage– Covers epiphysis where a joint

is formed– Reduces friction, absorbs

shock

Structure of bone

• Periosteum (per-ē-OS-tē-um)– (peri = around, osteo = bone)– Membrane surrounding a bone not yet covered by articular

cartilage– Essential for growth, repair, nutrition– Point of attachment for ligaments and tendons– 2 layers

• Outer – fibrous layer– Dense irregular connective tissue– Contains blood vessels, lymphatic vessels, and nerves

• Inner – osteogenic layer– Contains elastic fibers, blood vessels, and bone cells

Structure of bone

• Medullary (MED-yoo-lar-ē)– Also called marrow cavity– Space with in the diaphysis that contains yellow

marrow– In adults only

Structure of bone

• Endosteum (end-OS-tē-um)– Membrane lining the

medullary– Contains osteoprogenitor

cells

Structure of bone