Bone Flashcards
Functions of bone (4)
Weight bearing/support
Protection
Mineral store (ca2+)
Blood formation
Articular Cartilage
smooth white tissue that covers ends of the bone to form joints
Epiphyseal line/plate
Hyaline cartilage plate, located at each end of long bone where growth occurs in children and adolescents
Spongy bone/ Trabecular bone
Porous bone, highly vascularised and contains red marrow
Medullary cavity
Central cavity of bone shafts where red marrow and yellow marrow (adipose) is stored
Endosteum
Thin vascular membrane of connective tissue that lines surface of medullary cavity
Periosteum
a dense layer of vascularised connective tissue enveloping the bones, except surface of joints
Nutrient Foramen
Holes in the periosteum which feeds blood vessels into the bone
Osteons/Haversian System
Compact bone organised in circular structures
Features of Haversion System
Volkmann's Canal Haversian Canal Osteon Canaliculi Osteocyte Lamellae Lacunae
Canaliculi
Communication between cells
Lacunae
Contain osteocytes
Volkmann’s canal
Transport blood from periosteum into bone and communicate with Haversians system
Haversians canal
Allow blood vessels and nerves to travel through them
Types of bones
Flat bone (frontal) Sutural bone (fuse skull bones) Short bone (capal) Irregular bone (vertebrae) Sesamoid bone- patella Long bone (femur)
Two types of bone formation
Endochondral
Intramembranous
Endochondral
Most common in long bone growth
Intramembranous
common in flat bone, mandible, maxilla, clavicles)
Endochondral Ossification
Foetal hyaline cartilage model
Cartilage calcifies
Blood vessel invade cartilage
Primary ossification in diaphysis
Secondary ossification form in epiphysis
Bone replace cartilage except for epiphyseal growth plate
Growth plat eventually ossifies to form epiphyseal lines
Mesenchymal cells develop into___
Osteoprogenitor cells that mature into osteoblasts
Osteoblasts_____
deposit bone and residual mesenchymal cells develop blood vessels and bone marrow
Intramembranous ossification also occurs in
adult cortical bone
Osteoblasts secrete____
Osteoid
Osteoid
unmineralised, organic portion of bone matrix
Osteocyte
cells inside bone that come from osteoblasts
Bone consist of _____
45% hydroxyapatite crystals
35% Collagen type 1
20% water
Hydroxyapatite crystals
complex of calcium phosphate
Makes bone stiff and able to support structures
Collagen type 1
gives bone flexibility and reduce risks of fractures
High tensile strength
Water
important for mechanical properties
Bone Turnover/Remodelling
Osteoclasts break down old bone
Osteoblasts buld new bone
Howship’s Lacunae
Resorption pits
Osteoblasts become ____ once surrounded by ____
Osteocyte and matrix
Derived from haemopoietic cells (like macrophages) and found on bone surface
Osteoclasts
Osteoporosis
More resorption than formation due to loss of inhibitory effect of oestrogen
Brittle bones
Paget’s disease
Increase in formation
Leads to compression of nerves= deafness
