Bone Cartilage growth, repair and anatomy Flashcards
Describe the main roles of bone and cartilage tissue in the musculoskeletal system.
- Provide support
- Protection for vital organs
- Provide rigid rods and level which muscles can act to effect movement
- Multitude of organic ions (Calcium and phosphorus)
- Cartilage is found between 2 bones to prevent them rubbing together
What is bone tissue made up of?
- Matrix - organic and inorganic substances
- Cells - Osteocytes, Osteoblasts and Osteoclasts
- Vascular spaces
What matter can be found within the bones matrix?
Organic:
- Osteoid: ground substances to which many collagen fibres are embedded
- Collagen type 1 fibres (strong, inert structural component)
Inorganic:
- 60-70% dry weight
- Confer hardness and rigidity
- Make bone radio-opaque
What is the bone matrix surrounded by?
- It is embedded in a ground substance made from:
- Water
- Glycoproteins (bind collagen and minerals)
- Proteoglycans (bind growth factors)
- Bone sialoproteins (associated with cell adhesion)
What is woven bone?
- In early stages of life or following a fracture, the collagen fibres are not lined up in parallel
- This bone is formed and mineralised quicker, making it ideal in fracture repair
- This type of bone is not as strong as lamellar bone
What is lamellar bone?
- Parallel collagen fibres
- Thin layers of osteoid within
- Structurally superior (stronger)
Describe the Havarian system (The canals and surrounding lamellae)
- Primary Osteons are produced when the bone increases in diameter
- They run parallel to the long axis of the bone
- They contain one or more vascular canals (Haversian canals)
- They are ALWAYS surrounded by woven bone
- The vascular canals contain the blood vessels and nerves
- Tunnels that come off the primary Osteons are know as the secondary osteons and they allow more blood to travel through the bone
- Osteoclasts release enzymes that melt the bone too allow the tunnelling
- Osteocytes are scattered within the matrix and are connected o one another by dendritic processes
- Derived from the Osteoblasts
- Reside within Lacunae which are interconnected by canaliculi
- Maintain the bone matrix
What is an Osteoblast?
- Derived from mesenchymal cells
- Synthesise and secrete osteoid (the extracellular matrix of bone)
- Active in the mineralisation process
- Once the osteoblast is surround by the extracellular matrix it is known as an Osteocyte
What is an Osteoclast?
- Responsible for bone resorption
- Large cells, multiple nuclei
- Release protons to form an acidic environment, which causes demineralisation
- Derived from bone marrow
- Secrete protease enzyme, which destroys organic matter
Describe the process of bone modelling/remodelling
- Bone is excavated in cylindrical tunnels by the Osteoclasts
- Bone is then replaced by the Osteoblasts, they follow forming concentric lamellae/lamellar bone on the walls
- This surrounds a centrally in growing blood vessel (forming a secondary Osteon)
What does bone modelling/remodelling facilitate?
- Change in the bone shape
- Change in the bone material
- Repair of damaged bones
- Release of mineral ions
What is a stress fracture?
- Small incomplete fractures caused by repetitive exercise of the same area of bone
- Body tries to create more Osteons and if too many form the bone will become weaker
- This may result in more small fractures
- Often the cause of most catastrophic fractures
What is maladaptive remodelling?
- Body trying to fix the fracture by creating more bone in different places.
- Cause abnormal bone growth, bone may be going into soft tissue which will cause pain
What is a joint?
- Flexible interface between bones
- Smooth bearing surface
- Cartilage can grow from the inside (interstitial growth)
What is the differences between bone and cartilage?
- Biochemistry
- Microstructure
- Cell type
- Metabolism
- Cartilage is Avascular (no blood vessels)
- Aneural - no nerves
- Cartilage is often thin as it must get nutrients from tissue around it
