Bone Structure and Function Flashcards
Name some functions of bone?
- Structural function
- Mobility
- Support
- Protection for organs
- Storehouse & production for essential minerals (calcium, blood production)
- Fat production and storage
- Hearing (hammer, anvil)
Long bone features: what is the epiphysis, metaphysis and diaphysis?
Epiphysis (distal and proximal) ends of bone covered in cartilage, metaphysis (widened area of bone), diaphysis (shaft) Epiphyseal plate (bone growth)
Bone is a connective tissue. Describe its composition and % of each substance type.
Matrix of collagen fibres that give elasticity and ground substance which becomes calcified which gives brittleness to resist compressive forces.
25% water, 25% collagen, 50% crystalised mineral salts (calcium hydroxyapatite).
Light per unit volume.
4 types of cells. Osteogenic, osteoblast, osteocyte, osteoclast
Organisation of osseous tissue
- Compact cortical 80% solid hard layer (lateral impact not good)
- Spongey trabecular 20% honeycomb network, inner parts of axial skeleton and epiphyses of long bones (vertebrae, pelvis, good shock absorber and redistributes stresses).
Describe the intricasies of bone structure.
Blood vessell
Collagen fibres forming in criss cross fashion
Forming into spirals = lamellae
Layers and layers of lamellae = osteon / haverian system or canal
Lamellae in between
With lacunae of extra cellular fluid with osteocytes inside that have feelers out called canniculi that register what is occuring in the rest of the body
What type of bone is found in the ends (epiphysis) and shaft (diaphysis)?
Epiphysis = cancellous spongey bone Diaphysis = compact cortical
4 types of bone cell?
Osteogenic = undifferentiatied = can divide to produce osteoblasts
Osteoblasts = on surface, build matrix and collagen fibres, trapped in their own system
Osteocytes = mature osteoblasts, within lacunae and have projections called canniculi to monitor what is happening around bone
Osteoclasts = clear, reabsorb bone on surface of bone, release calcium back into blood.
What is osteogenesis imperfecta?
Common genetic bone disorder, don’t produce enough collagen, meaning these people have brittle bones. Susceptible to fractures - growth is slow and doesn’t grow in length as it should and is weak.
Paget’s disease?
Bone is replaced faster than usual, in the hast it is grown, it is weaker.
4 types of blood (artery) supply in bone?
1) Periosteal (through Volkman’s Canals to periosteum and osteons in OUTER cortical compact bone)
2) Nutrient (through diaphysis in nutrient foramen to medullary cavity and osteons of INNER cortical compact bone)
3) Metaphyseal (through metaphysis and supplies trabecular spongey bone and marrow)
4) Epiphyseal (through epiphysis and supplies trabecular spongey bone and marrow)
What is agenesis?
Affected limb has failed to form / doesn’t grow.
What is Spina Bifida?
Arteries around transverse processes of the spine do not form. Gap in spine. Spinal chord or meninges can protrude outwards in a fluid filled sack and cause paralysis.
What is achondroplasia?
Shortening of bone, long bones don’t grow, dwarfism.
Name some endocrine bone disorders?
Hyper/hypo parathyroidism (control of calcium)
Gigantism (increase in growth hormone)
Acromegaly (increase in GH after epiphyseal plates have formed - commonly affects bones of the face)
Pituatry dwarfism (inadequate GH production)
Postmenopausal OP (drop in oestrogen)
What nutritional problems can arise in bone?
Rickets / osteomalacia (softening of bones Vit D) drop in calcitrol - calcium not laid down
Scurvy (Vit C) osteoblasts not stimulated - bleeding gums and lose teeth
After 40 years old, what % bone mass per year do women and men lose?
Women = 8% Men = 3%
