The Skeletal System Flashcards
What is the structure of bone?
- Consists of a matrix (hardened by the deposition of mineral salts) in which cells are suspended.
- ORGANIC COMPOUND - called ‘osteoid’ made up of collagen and protein complexes. Strong, flexible and easily compressed.
- INORGANIC COMPOUND - called ‘hydoxapatite’ deposition of mineral salts (calcium, phosphate and carbonate) hard, relatively inflexible and brittle
Describe the structure of bone tissue
COMPACT - on the surface of the bone. Dense tissue in concentric circles- structured to resist stress. Very strong.
CANCELLOUS - trabeculae of cancellous bone arranged haphazardly to take stress from different directions. Less heavy than compact bone and spaces in the trabeculae contain bone marrow!
What are the 3 stages of INTRAMEMBRANOUS ossification?
1) Mesenchymal cells secrete organic component of the bone (osteoid). Deposition of calcium salts leads to calcification. Mesenchymal cells differentiate into osteoblasts
2) Blood vessels grow into area to supply nutrients (O2)
3) Initially only cancellous bone but remodelling occurs and compact bone develops.
What are the 6 stages of ENDOCHONDRIAL ossification?
1) Cartilage model laid down
2) Outer cells differentiate into osteoblasts and produce a thin outer collar of bone. Blood supply develop.
3) Cells in diaphysis differentiate into osteoblasts - primary ossification centre
4) Osteoclasts erode centre of diaphysis - marrow cavity
5) Secondary ossification centres develop in the epiphyses and epiphyseal cartilage replaced by bone.
6) Thin plate of cartilage remains at the metaphysis - epiphyseal plate
Summarise the stages of bone healing
1) Haemotons formation between the ends of bone and in surrounding soft tissues
2) Area invaded by capillaries, fibroblasts, macrophages, osteoclasts and osteogenic cells. Soft callus forms
3) Soft callus hardened by mineral deposition (bony callus)
4) Remodelling by osteoclasts
Classify bones according to shape and name an example
- LONG BONES - Longer than they are wide, act as levers (femur, metatarsals, phalanges)
- SHORT BONES - Nearly equal in length and width, glide across one another (carpals and tarsals)
- FLAT BONES - protect organs and serve for muscle attachment (sternum, scapula, pelvis and cranial bones
- IRREGULAR BONES - Serve for muscle attachment (vertebrae, some skull bones)
Describe the ‘appendicular skeleton’
- 126 bones
- Pectoral girdle, upper limb, pelvic girdle and lower limb.
Describe the ‘axial skeleton’
- Consists of 80 bones
- Skull, vertebral column, ribs and sternum
Describe how osteoporosis affects bone
- Bone density is reduced because it’s deposition does not keep pace with reabsorption
- It is fragile and microscopically abnormal with the loss of internal structure.
- Peak bone mass is 35yrs and then gradually declines
- Lower oestrogen levels after menopause contribute
- Higher risk of fractures
What are the function classifications of joints?
- SYNARTHROSIS - little or no movement (eg. Suture)
- AMPHIARTHROSIS - Slightly moveable (eg. Intervertebral discs)
- DIARTHROSES - freely moveable (eg. Hip)
What are the structural classifications of joints?
- CARTILAGINOUS - bones held together by cartilage (eg. Intervertebral discs)
- FIBROUS - bones held together by collagenous fibres (eg. Skull sutures)
- SYNOVIAL - bones separated by a joint cavity and enclosed in a fibrous capsule (eg. Hip)
What is an example of a ball and socket joint?
Shoulder
Permits flexion, extension, abduction, addiction, circumduction and rotation
What is an example of a hinge joint?
Elbow
Permits flexion and extension
What is an example of a gliding joint?
Sternoclavicular
Permits sliding
What is an example of a pivot joint
Atlantoaxial
Permits flexion, extension, abduction and adduction
