Bone Flashcards
Name 2 types of bone tissue , where they are found and what main base is made from
1.Compact bone - outer part bones
made of Haversion systems (osteon )
- Trabecular bone ( spongy) bone
inside bony mesh ( supports myeloid tissue -red bone marrow forms blood cells )
What’s the composition of bone extracellular matrix and their function
know
67% Inorganic - hydroxyapatite ( calcium phosphate crystals+ calcium salts )
= hardness and resistance to compression force
33%)- organic -28% collagen ( Type 1 mostly ) + 5% non collagen proteins ( proteoglycans )
= tensile strength of bone
Name 3 kinds of bone ,what like and an example
- Long - femur
- Flat- 2 compact layers with spongy filling between them eg skull bones
- Sutural - small and irregularly shaped between flat bones e.g coronal suture between temporal and frontal bone,
Name 5 functions bone
1.Support body upright
2.Protect -organs inside body
3.Movement -
4.Mineral storage - hydroxyapatite major reservoir calcium/phosphorus
5. haematoporesis- makes red blood cells in red bone marrow by myeloid
where is blood made in bones
in red bone marrow by myeloid tissue(haematopoiesis )
Name 3 bone cells and function
1.Osteocytes- allow nutrient/waste exchange betweencells( these are mature osteoblasts caught in lamella )and secrete bone matrix proteins
2. Osteoclasts- clean bone up/break it down
3. Osteoblasts- build bone
What is the Haversian system other name
Osteon
Describe an Osteon
( YOU SAID KNOW )
Basic unit compact bone
Central canal ( Haversian canal ) caring blood vessels, nerves, lymphatics surrounded bycylindrical lamella ( calcified layers made by osteoblasts
Osteons connected by Volkmanns canal
Have Osteocytes (osteoblasts surround by osteoid trapped in their lacunae ) connect to each other thru canaliculi
What’s a Volkmans canal
Channels that connects osteons to each other
What cells are used in bone remodelling
(KNOW )
Osteoclasts _ breakdown bone( clean up bone )
Osteoblasts - build new bone via osteoid
What do osteoblasts secrete
Osteoid
Name 4 bone cell types and what do
(YOU HAD KNOW )
- Osteogenic cells (Stem cells turn into osteoblasts)
- Osteoblasts ( builders of extracellular bone matrix)
- Osteoclasts ( clean up/break down ( remodel ) bone extracellular matrix
- Osteocytes - mature bone cells , maintain bone ( osteoblasts caught in lacunae )
Describe an osteoblast
cell
arise from osteogenic stem cells in periosteum /endosteum of bone)
lots Golgi as secrete osteoid
Lots rough endoplasmic reticulum
describe an osteoblasts function
Cause Apposition ( growth bone)
Synthesise and secrete osteoid ( mostly type 1 collagen ) __> osteoid calcifies ( start apposition )
Describe as osteocyte
Mature osteoblast caught in lacuna by its secreted matrix - secretes bone matrix proteins so maintains bone ‘
Communicate to each other by canalculi
Describe osteoclasts
(YOU HAD KNOW WELL )
multi nucleated cells
lots gologi , mitochondria and RER ( rough endoplasmic reticulum)
Concentrated in endosteum of bone in Howship lacunae
Describe the function osteoclast
( YOU SAID KNOW )
Involved in bone resorption ( remodelling bone)
( part of normal bone growths well as development /repair )
- Osteoclast attaches to mineralised bone surface at ruffled edge /sealed zone )
- In sealed zone acidic environment forms and bone demineralised
- Exposed bone matrix degraded by lysosome enzymes ( Alkaline phosphatase )- Howship lacunae form
- Endocytosis of degraded product at ruffled border
- Waste exported to other end of cell
How does bone remodelling occur
(KNOW )
Osteoclasts attach ruffled border of bones —>
form a acidic environment ( demineralises bone ) - –> exposed matrix is degraded - causing Howship lacunae depressions —> degraded product endocytose and get removed to other end of the cell .
Osteogenic stem cell –> osteoblast –> secrete osteoid - making new calcifications as osteoclasts clean up as above ( WOrK TOGETHeR )
Name 2 bone conditions
Osteoporosis - in woman especially, MOST COMMON
Due to
1. Low hormone levels ( oestrogen /tesosterone ) PLUS inadequate calcium/vit D
—>
2.Loss trabecular bone density so loss calcified matrix
See
Porous fragile bones/break easily
Treatment : oestrogen and supplements calcium/vit d
and calcitonin nasal spray to increase calcium storage in bone
Osteomalacia-
metabolic disorder -Osteoid not calcify properly as
cant absorb vitamin d /calcium ) –>weak bones/muscle wasting /fractures
- txn :supplements calcium and vit d, sunlight ( a vitamin d source )
Name 2 types of bone ossification/healing
Endochondral ossification - turns cartilage into bone
Intramembranous- formation bone when no cartilage present
what is endochondral ossification
Cartilage turning into bone
Seen in fracture healing or growth of bones ( also in embryo )
- epiphyseal plates add cartilage that later becomes bone tissue elongating the bones
what is intramembraneous ossification
Formation bone tissue when no cartilage is present
- occurs in embryo from osteoblasts
Difference between cortical and cancellous ( spongy ) bone
Cortical - dense hard bone ( strong )
Cancellous - spongy in spine and long bones ends
Discuss bone organisation on the jaw
( YOU HAD KNOW )
1.Alveolar bone proper -plates compact bone around teeth
2.Alveolar bone facial/lingual surfaces -compact (cortical) and trabecular bone supporting
- Between alveolar bone proper and Cortical bone -= Trabecular bone - spongy bone
- Interdental/interradicular septa - compact plates + spongy bone
- Alveolar bones ( compact bone on outside - trabecular inside )
Explain what happens if a bone fractures how heals
1.Break - bone death /vascular damage
2.Bone blood clot forms
3.Fibrin mesh forms’Granulation via fibroblasts /inflammation cells
4.Bony callus forms ( ext callus and spongy internal callus )
5. Formation /remodelling new bone by osteoclasts and osteoblasts activity
