Chapter 7 Skeletal Tissues Types of Bones There

Chapter 7 Skeletal Tissues

Types of Bones • There are four types of bones (Figure 7 -1): – – Long bones Short bones Flat bones Irregular bones • Bones serve various needs, and their size, shape, and appearance will vary to meet those needs

Types of Bones – Long • Extended longitudinal axes • Uniquely shaped articular ends • Humerus and femur

Types of Bones – Short • Cube or box-shaped • As broad as they are long • carpals, tarsals, phalanx

Types of Bones – Flat • Broad and thin • Skull, scapula, ribs, breastbone

Types of Bones – Irregular • Clustered in groups • Various shapes and sizes • Vertebrae, facial bones, patella

Types of Bones • Bones vary in their proportions of compact and cancellous (spongy) bone – Compact bone is dense and solid in appearance – Cancellous bone is characterized by open space partially filled with needle-like structures

Types of Bones • Parts of a long bone (Figure 7 -2) – Diaphysis • Main shaft of long bone • Hollow, cylindrical shape • Thick, compact bone • Function is to provide strong support without cumbersome weight

Types of Bones • Parts of a long bone (cont. ) – Epiphyses • Both ends of a long bone • Made of cancellous bone filled with marrow • Bulbous shape • Function is to provide attachments for muscles and give stability to joints

Types of Bones • Parts of a long bone (cont. ) – Articular cartilage • Layer of hyaline cartilage that covers the articular surface of epiphyses • Function is to cushion jolts and blows

Types of Bones • Parts of a long bone (cont. ) – Periosteum • • • Dense, white, fibrous membrane that covers bone Attaches tendons firmly to bones Contains cells that form and destroy bone Contains blood vessels important in growth and repair Contains blood vessels that send branches into bone Essential for bone cell survival and bone formation

Types of Bones • Parts of a long bone (cont. ) – Medullary (or marrow) cavity • Tubelike, hollow space in diaphysis • Filled with yellow marrow in adult – Endosteum—thin epithelial membrane that lines medullary cavity

Types of Bones • Short, flat, and irregular bones – Inner portion is cancellous bone, covered on the outside with compact bone – Spaces inside cancellous bone of a few irregular and flat bones are filled with red marrow

Bone Tissue • Most distinctive form of connective tissue • Extracellular components are hard and calcified • Rigidity of bone allows it to serve its supportive and protective functions • Tensile strength is nearly equal to cast iron at less than one third the weight

Bone Tissue • Composition of bone matrix – Inorganic salts • Hydroxyapatite—highly specialized chemical crystals of calcium and phosphate contribute to bone hardness • Slender, needle-like crystals are oriented to most effectively resist stress and mechanical deformation • Magnesium and sodium are also found in bone

Bone Tissue • Composition of bone matrix (cont. ) – Measuring bone mineral density • Osteoporosis – loss of bone mineral density • Affects 45% of untreated women during the first 10 years after menopause – Organic matrix • Composite of collagenous fibers and an amorphous mixture of protein and polysaccharides called ground substance • Ground substance is secreted by connective tissue cells • Adds to overall strength of bone and gives some degree of resilience to the bone

Quick Check • List the six structural components of a typical long bone that are visible to the naked eye. • Identify the two principal chemical components of bone matrix. • What disease is characterized by a loss of bone mineral density?