Skeletal tissue and system

Skeletal systemBones and cartilage

Protect organsAllow for motion

Orthopaedics(Orthopedics)Medical specialty for restorative treatment of skeleton and articulations (joints) and associated connective tissue

Skeletal system tissueCartilageBoneDense connective

Skeletal system functionsSupportProtectionMovement (along with attached muscle)Mineral Storage (calcium)Storage and production of blood cell – red marrow (hematopoiesis)Energy storage -yellow marrow

Bone tissue cell types

Osteogenic (osteoprogenitor) cells

From mesenchymeCan proliferate (mitosis)Can differentiateIn periosteum, endosteum and canalicula

OsteoblastsForm boneProduce & secrete organic (collagenous) componentsProduce & secrete mineral salts (hydroxyapatite; calcium phosphate, calcium carbonate)Can no longer divide

OsteocytesMajor cell of bone tissue“Mature” bone cellsMaintain boneTrapped in their own secretions

OsteoclastsReabsorb bone (degrade bone)Critical for remodeling and development and repairLocated on bone surface

Types of bone

Long bone structureDiaphysis – shaft / main portionEpiphysis – endsMetaphysis – btwn dia & epiphysisCartilage – hyaline for shock absorption and friction reductionPeriosteum – dense covering of two layers for growth, repair & attachments

Elastic fibers and blood vesselsOsteogenic, -clast & -blast cells

Long bone structure

Medullary cavity (bone marrow)Within diaphysisYellow bone marrow in

adultsFat and blood cells

Endosteum – lines medullaOsteoblasts and clasts

Compact bone and spongy bone

Compact and spongy bone

Compact bone characteristicsLittle space

Thick in diaphysis

Thin in epiphysis

Protection and support

Compact bone structureRings of bone material - Osteons– Contain osteocytes– Lacunae – space in which osteocytes are trapped– Canaliculi – connect to lacunae, “little canals” for

nutrient and waste distribution– Central canals – lead to perforating canals

Spongy bone

Spongy boneNo true osteonsTrabeculae – irregular thin bone platesRed marrow between trabeculae

Produces blood cells

Osteocyte containing lacunae within trabeculae

Bone FormationIntramembranous Ossification

Formation of bone within fibrous membranesForms flat bones of skull

Endochondral ossificationMost common type of bone formationBone forms from cartilage

Intramembranous Ossification

Intramembranous Ossification

Endochondral Ossification

Endochondral Ossification

Endochondral Ossification

Bone disordersOsteoporosis

Bone disordersOsteomalacia (rickets in children)

Bone disordersOsteomyelitis

Bone disordersOsteoarthritis

Bone disorders

Bone fractures

Bone repair

Calcium Homeostasis

PTH (parathyroid hormone)

Calcitonin