Bones & Joints Flashcards
Describe the matrix components of bone
specialised connective tissue
Strong flexible shatter resistant Matrix made of:
- strong, flexible organic component: osteoid, collagen & protein complexes
- hard, inflexible inorganic component: hydroxyapatite, mineral salts, CaPhosphate, CaCO3
Describe 4 types of bone cell
Osteogenic stem cells in periosteum/endosteum, develop into osteoblasts
Osteoblasts secret osteoid, deposit minerals for new bone
Osteocytes are mature bone cells in lacunae within bone to maintain matrix
Osteoclasts remove minerals from matrix to remodel bone
Describe 2 types bone tissue
Compact - on bone surface provides strength for weight bearing (osteons in same direction) and prevents buckling
Cancellous (spongy) - interior, trabeculae arranged haphazardly (marrow between) lighter than compact
Describe bone marrow
spaces between trabeculae of spongy bone and medullary cavities of long bones
Red - myeloid tissue (haemopoietic)
Yellow - fatty tissue doesn’t produce blood (can transform back in severe anaemia)
In what 4 ways is bone shape classified?
Long (levers) - femur, metatarsals, phalanges
Short (= length/width glide across each other) - carpals/tarsals
Flat (organ protection/muscle attachment) - sternum, scapula, pelvic, cranial
Irregular (muscle attachment) - vertebrae, some skull
Describe bone formation and name 2 methods
Ossification/Osteogenesis
Intramembranous or endochondral ossification
Describe intramembranous ossification
occurs in flat bones/clavicles
- mesenchymal cells secrete osteoid, deposited calcium salts cause calcification, mesenchymal cells differentiate to osteoblasts
- blood vessels grow into area supplying nutrients/O2
- initially only cancellous bone but can be remodelled into compact
Describe endochondral ossification
- cartilage laid down, outer cells differentiate into osteoblasts producing thin outer bone collar developing blood supply
- Diaphysis cells differentiate into osteoblasts in primary ossification centre
- Osteoclasts erode diaphysis centre forming marrow cavity
- Secondary ossification centres develop in epiphyses where bone replaces cartilage. Metaphyseal thin plate cartilage remains forming epiphyseal plate
How do bones grow?
New cartilage constantly laid down at epiphyseal side of plate, invaded by osteoblasts to be replaced by bone
speed of cartilage growth > osteoblast activity growth continues, at puberty GH/Thyroid Hormones increase halting growth
How are bones remodelled?
Calcium salt deposition/resorbed as required
Bone thickens to increase strength
Old bone renews and injured bones replaced
What are the types of fracture?
Compound (open) or simple (closed)
Greenstick
Comminuted
Linear
Transverse
Oblique
Spiral
Describe bone healing and inhibitory factors
- haematoma invaded by capillaries/fibroblasts/macrophages/osteoclasts
- Soft callus formed/hardened by mineral deposition (bony callus), remodelled by osteoclasts
Delayed by:
low blood supply
infection
tissue fragments/poor alignment/continued mobility of bone ends
Systemic illness, malnutrition, age, drugs (corticosteroids)
What are the functions of the skeleton?
structural support
protect internal organs
stores Ca
produce blood cells
provides leverage for movement
Describe the 3 structural classifications of joints
Fibrous - dense irregular connective tissue, collagen-rich e.g. sutures in skull, syndesmosis via ligament/DnsIrrCT
Cartilaginous - primary hyaline (longbone epiphyseal plate) secondary fibrocartilage (vertebrae/symphasis pubis)
Synovial - separated by joint cavity enclosed in fibrous capsule (interphalyngeal): synovial membrane and articular cartilage enclosed
Describe 3 functional classifications of joints
Synarthroses - immovable fibrous/cartilaginous (sutures/epiphyseal plate)
Amphiarthroses - slightly movable fibrous/cartilaginous (interosseous membrane/symphasis
Diarthroses - freely movable (all synovial)
