Skeletal system Flashcards
What are the functions of the skeletal system?
Structural support Protects organs Provides leverage for movement Stores calcium Produces blood cells
Describe the bones structure (matrix)
Organic component: OSTEOID
- made up of collagen and protein complexes
- strong, flexible but easily compressed
Inorganic component: HYDROXYAPATITE
- deposition of mineral salts mainly Ca+ phosphate and Ca+ carbonate
- hard, relatively inflexible and quite brittle
Combination of 2 = strength and flexibility, resistance to shattering
Name and describe the 4 types of bone cell
- OsteoBLASTS - produce new bone, secrete osteoid, responsible for mineral deposition
- OsteoCYTES - mature bone cell, maintain the matrix
- OsteoCLASTS - remove minerals from the matrix, bone remodelling
- Osteogenic stem cells - found in periosteum and endosteum, develop into osteoblasts
Describe bone structure (tissue)
Compact bone - located on the surface of the bone
Cancellous/spongy bone - located on the interior of the bone, less heavy than compact, spaces between trabeculae contain bone marrow
Name and describe the different types of bone marrow
Found in spaces between trabeculae of spongy bone, and medullary cavities of long bones
> Red bone marrow - myeloid tissue (haempoietic)
> Yellow bone marrow - fatty tissue, doesn’t produce blood (can transform back in severe anaemia)
Name the 4 classifications of bones by shape
- Long bones are longer than they are wide, act as levers eg. femur, phalanges, metatarsals
- Short bones are nearly equal in length & width, glide across each other eg. carpals & tarsals
- Flat bones protect organs and serve muscle attachment eg. sternum, scapula, pelvic and cranial bones
- Irregular bones serve for muscle attachment eg. vertebrae
Name the 2 methods of bone formation
Intramembranous ossification
Endochondral ossification
Intramembranous ossification
Occurs in flat bones and clavicles
3 stages:
- mesenchymal cells secrete osteoid, deposition of Ca+ salts leads to calcification, mesenchymal cells can differentiate into osteoblasts
- blood vessels grow in area to supply nutrients and oxygen
- cancellous bone develops first, remodelling occurs and compact bone develops
Endochondral ossification
- Cartilage model laid down
- Outer cells differentiate into osteoblasts, produce thin outer collar of bone, blood supply develops
- Cells in diaphysis differentiate to osteoblasts, primary ossification centres
- Osteoclasts erode centre of diaphysis = marrow cavity
- Secondary ossification centres develop in epiphyses and epiphyseal cartilage replaced by bone
- Think plate of cartilage remains at the metaphysis = epiphyseal plate
Describe bone growth
Osteoblasts invade the cartilage from the shaft side and replace it with bone
As long as the speed of cartilage growth excedes the rate of osteoblast activity the bone will continue to grow in length
Puberty = increase in sex, growth and thyroid hormones which increases stimulation of bone growth, osteoblast activity catches up with cartilage formation = bone growth halts
Describe bone remodelling
Ca+ salts are deposited and reabsorbed as required
Bone thickened = increases strength in areas of physical stress
Old bone renewed and injured bone replaced
Name the 6 types of fractures
Bones fracture (break) if subjected to extreme loads, sudden impacts or stresses from unusual directions Can be compound (open) or simple (closed) 1. Greenstick 2. Comminuted 3. Linear 4. Transverse 5. Oblique 6. Spiral
What is the process of a bone healing?
- Haematoma formation
- Area invaded by capillaries, fibroblasts, macrophages, osteoclasts and osteogenic cells, soft callus forms
- Soft callus hardened by mineral deposition
- Remodelling of osteoclasts
Takes up to 7 weeks, requires a good blood supply and freedom from infection
Name the factors that delay healing
Deficient blood supply Tissue fragments between bone ends Poor alignment of bone ends Infection System illness Malnutrition Ageing Drugs eg. corticosteroids
What is a joint?
An area where 2 bones meet
