322138
Description
Mind Map by Amber Basra, updated more than 1 year ago
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Created by Amber Basra
about 11 years ago
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Bone
- A highly vascular connective tissue
made of specialised cells in a matrix
composed of minerals, water and protein
fibres.
- 2 types
- Compact (dense)
- Forms the surface layers of mature bones
- found mainly in shafts of long
bones (where strong, tubular
structure is required)
- consists of a no. of cylindrical
structures called haversian systems
(or osteons) which contain:
- a central haversian canal
- lamellae
- lacunae
- canaliculi
- interstitial lamellae
- circumferential lamellae
- Volkmann's canals
- periosteum
- a central haversian canal
- Forms the surface layers of mature bones
- Cancellous (spongy)
- found in parts of bone where
lightness, strength and area are
required
- has trabeculae instead of osteons
- plates and bars of bones
arranged in a haphazard
manner
- organised to
provide max
strength
- follow lines of
stress and can
realign if direction
of stress changes
- contain: lamellae, osteocytes, lacunae and canaliculi
- canaliculi connect to
adjacent cavities
instead of a central
canal
- canaliculi connect to
adjacent cavities
instead of a central
canal
- BONE MARROW
found between
trabeculae
- at birth it is red and produces cells in the blood e.g. RBCs, WBCs.
- in adults, red found in: upper
femora, vertebrae, scapulae,
sternum, clavicles, diploe of skull
bones and hip bones.
- elsewhere, red becomes inactive
yellow marrow
- elsewhere, red becomes inactive
yellow marrow
- at birth it is red and produces cells in the blood e.g. RBCs, WBCs.
- plates and bars of bones
arranged in a haphazard
manner
- found in parts of bone where
lightness, strength and area are
required
- Compact (dense)
- OSSIFICATION - Formation of bone from connective tissue
and requires: adequate calcium and phosphate in blood and
vitamins A, C and D.
- influenced by hormones:
parathormone, growth hormone,
thyroxine and testosterone
- intramembranous - takes place in a membrane
- osteogenic fibres and bone cells appear in the connective
tissue and calcium salts deposited to form osteoid tissue
- ossification spreads from the centre outwards
- osteogenic fibres and bone cells appear in the connective
tissue and calcium salts deposited to form osteoid tissue
- intracartilaginous
- process by which bone formation takes place e.g. in a long bone
- Primary centre of ossification - middle of diaphysis, osteoblast
appear and calcium is laid down, osteoclasts remodel bone into
required shape, bone is also being built up on outside of shaft to
form periosteum
- Secondary centre of ossification - appears at
end of bone to form epiphyses (which are
separated from diaphysis by epiphyseal plate
- Growth - occurs during childhood by production
of bone at epiphyseal plate nearest shaft -
metaphysis.
- Fusion- of epiphysis with diaphysis
occurs when bone reaches desired
size (approx. 20 years)
- Fusion- of epiphysis with diaphysis
occurs when bone reaches desired
size (approx. 20 years)
- Growth - occurs during childhood by production
of bone at epiphyseal plate nearest shaft -
metaphysis.
- Secondary centre of ossification - appears at
end of bone to form epiphyses (which are
separated from diaphysis by epiphyseal plate
- Primary centre of ossification - middle of diaphysis, osteoblast
appear and calcium is laid down, osteoclasts remodel bone into
required shape, bone is also being built up on outside of shaft to
form periosteum
- process by which bone formation takes place e.g. in a long bone
- influenced by hormones:
parathormone, growth hormone,
thyroxine and testosterone
- Functions
- Shape
- Protection
- Movement
- Sound transduction
- Production of RBCs- haematopoiesis
- Mineral storage
- Growth factor storage
- Fat storage
- Shape
- Types of cells within bone
- Osteogenic cell - found in inner
layer of periosteum - develops into
osteoblasts
- Osteoblast - forms bone matrix
- Osteocyte - mature bone cell which maintains
bone tissue
- Osteoclast - functions in bone resorption and
remodelling
- Bone tissue is maintained by a balance between the activity of
osteoblasts that form bone and osteoclasts that break it down -
remodelling
- Bone tissue is maintained by a balance between the activity of
osteoblasts that form bone and osteoclasts that break it down -
remodelling
- Osteogenic cell - found in inner
layer of periosteum - develops into
osteoblasts
- BLOOD SUPPLY
- Periosteum has arteries which supply it and also enter the diaphysis
through many perforating Volkmann's canals - this supplies the outer part
of compact bone
- A hole in compact bone (nutrient foramen)
allows passage of nutrient artery into
medullary cavity
- Divisions supply inner part of compact bone, spongy bone and red marrow
- nutrient arteries divide into ascending
and descending branches in medullary
cavity
- some bones have 1 nutrient artery (tibia) and some have several (femur)
- nerves also pass through same nutrient foramen
- Divisions supply inner part of compact bone, spongy bone and red marrow
- broken bones are
very painful as
periosteum is richly
supplied with nerves
- A hole in compact bone (nutrient foramen)
allows passage of nutrient artery into
medullary cavity
- Periosteum has arteries which supply it and also enter the diaphysis
through many perforating Volkmann's canals - this supplies the outer part
of compact bone
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