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Flashcards in Bones Deck (14):

Give four functions of bone and an example of each

Mechanical - support and attachment for muscles, tendons, ligaments and joints

Protective - protects internal organs

Metabolic - mineral reservoir for calcium and phosphate homeostasis

Haematopoiesis - support blood formation


Describe the development of bone as a result of endochondral ossification

- bone forms as cartilage first during third month of development
- blood vessels and osteogenic cells invade the cartilage framework
- the cartilage remains as growth plates
- growth plates fuse at approx. 18 in females and 21 in males


Describe the development of bone as a result of intramembranous ossification

- bone forms as a fibrous plate
- bone cells differentiate from fibroblasts and haemopoietic precursers
- no cartilaginous phase


Describe the composition of bone

- 20% water
- 35% protein - collagen type I (provides toughness), growth factor proteins, other organic matrix proteins
- minerals - hydroxyapatite (provides rigidity)


The epiphyses of long bones are composed of

trabecular (spongy) bone - acts as a softer interface at joints


The diaphysis of long bones is made up of

cortical bone


Cortical bone is

- denser
- arranged into Haversian Systems from the way the collagen molecules form fibrils which then form fibres and finally sheets
- structure gives the bone its strength


Give the two main cells involved in bone maintenance and renewal

- osteoclasts
- osteoblasts


Osteoclasts are

- the bone resorbing cells
- derived from haemopoietic lineage


Osteoblasts are

- responsible for laying down more come
- derived from mesenchymal lineage


Bones are constantly monitored and remodelled to

keep them at peak strength


Osteoclasts will absorb any area of bone that has been



When damaged areas of bone have been absorbed, osteoblasts will

lay down new bone in the same area


Osteocytes act as sensors of

mechanical pressure and damage