Week 5 Flashcards
What are the 5 functions of bone?
Structural foundation
Mobility
Support
Protection
Storehouse for essential minerals
What is the end of a long bone called?
Epiphysis
What does diaphysis mean?
The shaft of the bone
What is a medullary
The hole in the bone
What is a endosteum
A sheeth
What is the matrix of bone?
25% water, 25% collagen and 50% crystallised mineral salts, calcium hydroxyapatite
Another word used for compact bone?
Cortical
Another word for spongy bone
Trabecular or cancellous
What percentage does compact (cortical) make up of the bone mass?
80%
Trabecular bone makes up what percentage of bone mass
20%
What is the periosteum
Vascular membrane, inner layers contain osteoblasts and osteoclasts and the outer layer is tough and fibrous.
What does the Haversian canal contain?
Blood vessels and nerves
What is the lunellae
Series of cylindrical plates arranged around a central canal
Lacunae
Strings of little cavities in which osteocytes sit
Canaliculi
Tiny network of channels which allows the lacunae to communicate. Allows for interstitial fluid to circulate through the bone and direct contact between osteocytes
Which type of bone withstands stress better
Spongy bone
What are the four types of bone cells
Osteogenic/osteopogenitor cells
Osteoblasts
Osteocytes
Osteoclasts
Where are osteogenic cells found
Endosteum, inner layer of periosteum
Undifferentiated cells
Where are osteoblasts found in
Surface of bone than in lacunae
They build the matrix and collagen fibres
Osteoclasts
Clear bone cells. Biggest of the bone cells. Reabsorb dead bone cells to clear deadbry
What are the four types of blood supply to bones
Periosteal arteries
Nutrient arteries
Metaphyseal arteries
Epihyseal arteries
Where are periosteal arteries found
Periosteum and outer osteons of compact bone
Where are nutrient arteries found
Medullary cavity and osteons of inner compact bones
Where are metaphseal arteries found
Spongy bone and marrow
Where are epiphyseal arteries found
Spongy bone and marrow
Why is osteopenia worse in women
Low oestrogen levels after menopause
What is agenesis
Limb that does form or partially forms
Osteogenesis imperfecta
Genetic low collagen
Spina bífida
Vertebrae do not develop arches so spinal cord protrude
Achondroplasia
Long bones don’t grow
What disorders affect remodelling
Age, hormone levels, calcium and phosphate and mechanical stress
What nutritional problems lead to bone disorders
Rickets, scurvy and osteomalacia
What are some endocrine disorders that affect bones
Gigantism, acromegaly, pituitary dwarfism, hyper/hypoparathyroidism
The 4 stages of healing a fracture
1 hematoma formation
2 fibrocartilaginous callus formation
3 bony callus formation
4 bone remodelling
How long do bones bleed for?
6-8hrs
What is fibrocartilagenous callus formation also called?
Union
What happens at the fibrocartilageous callus formation stage
Fibroblasts invade pocallus and lay down collagen
Chondroblasts produce fibrocartilage
Lasts 3-4 months
What happens in formation of bony callus (consoldiation)
Osteoblasts secrete spongy bone that joins the broken ends
Lasts 3-4 months
What happens in bone remodelling
Compact bone replaces spongy bone in the callus
Surface is remodelled back to normal shape
Sometimes a palpable lump
Takes1 year
