Bone Flashcards
What are the four main functions of bone?
- Weight bearing/ support
- Protection (e.g. skull protecting brain)
- Mineral store
- Blood formation
What is the difference between cortical and trabecular bone?
Cortical (Hard) bone is more compact than trabecular (spongy) bone
What is the difference between the periosteum and the endosteum?
The periosteum is the outer membrane and the endosteum is the inner membrane.
What are Haversion systems?
Compact bone organised into circular structures
What is the difference between Haversion canals and Volkmann’s canals?
Haversion canals lead up the centre of Haversion systems.
Volkmann’s canals lead horizontally through Haversion systems.
What is the other name for Haversion systems?
Osteons
What are the 6 types of bone?
- Sutural bone
- Flat bone
- Long bone
- Short bone
- Irregular bone
- Sesamoid bone
Where do sesamoid bones occur?
Where there is a risk of friction
What are the two types of bone formation?
Intramembranous and Endochondral
Describe endochondral bone formation.
Hyaline cartilage model is replaced by bone
Describe intramembranous bone formation.
(Membrane becomes replaced by bone)
Mesenchymal cells develop into osteoprogenitor cells
Osteoprogenitor cells mature into osteoblasts
Osteoblasts deposit bone
Residual mesenchymal cells develop into blood vesseks and bone marrow.
What bones are formed by intramembranous ossification?
Flat bones of skull, face, jaw and clavicle
What three cells are present in bone?
Osteoblasts, Osteoclasts, Osteocytes
What are the constituents of bone extracellular matrix?
Hydroxyapatite crystals
Type 1 Collagen
Water
From what cells are osteoblasts formed?
Osteoprogenitor cells
What is the function of osteoblasts?
Produce bone matrix and initiate calcification
From what cells are osteoclasts formed?
Monocytes/ macrophages
What is the function of osteoclasts?
Reabsorb bone matrix
How are osteocytes formed?
From maturation of osteoblasts once surrounded by matrix.
What is though to be the function of osteocytes?
Maintenance of bone matrix
Sense mechanical forces
What is the role of canaliculi?
Connect lacunae to allow cell to cell communication
From what compound are hydroxyapatite crystals formed?
Calcium phosphate
What is the function of hydroxyapatite crystals in the extracellular matrix?
Makes bones stiff for support and gives high tensile strength.
What is the role of the collagen found in the extracellular matrix of bone?
Allows flexibility of bone to make it less brittle.
What processes characterise osteoporosis?
Greater reabsorption than formation
What processes characterise Paget’s disease?
Increased reabsorption and Formation
What process characterises osteopetrosis?
Decreased reabsorption
