Bone formation and fracture healing Flashcards
Types of connective tissue
Embryonic tissue, Mature tissue
3 types of mature tissue
Connective tissue proper- loose or dense
supporting connective tissue- cartilage and bone
liquid connective tissue- blood or lymph
What does cartilage consist of?
A dense network of collagen fibres and elastic fibres; embedded in chondrotin sulphate.
What is chondrotin sulphate?
A gel like component of the ground substance
What does bone further subcategorise into?
Compact bone and Spongey bone
Functions of the skeletal system and bones
-Support
-Protection
Assistance in movement
-Mineral Homeostasis
-Blood cell production (Hemopoiesis)
-Triglyceride storage
Features of cartilage (5)
-More flexible than bone
-Tough and shock absorbs
-Avascular
-Gets nutrients via diffusion from the pericadium or synovial fluid
-Maintains pliable support for structures
Types of bones
Long bone
Short bone
Flat bone
Sesamoid bone
Long bone features and examples
Longer than they are wide, Unique shaped ends for articulations e.g femur, humerus
Short bone features and examples
Often cube/box shaped, about as long as they are wide e.g carpal and tarsal bones
Irregular bone features and examples
Often in groups and various shapes and sizes e.g vertebrae in spine and facial bones
Flat bone features and examples
Often broad, thin, flat e.g scapulae, ribs, sternum
Sesamoid bone features and examples
Found in tendons
Reduce friction on tendons
absorb and redistribute weight-bearing forces e.g patella
Structure of bone
Diaphysis, Epiphysis, Metaphysis, Articular cartilage, Periosteum, Medullary cavity, Endosteum
The diaphysis part of bone features
Is the bone’s shaft or body. It is hollow, yet thick and compact
The epiphysis part of bone features
Are the proximal and distal ends of the bone.
The metaphysis part of bone features
Are the regions between the diaphysis and the epiphysies.
The articular cartilage feature of the bone
A thin layer of hyaline cartilage covering the part of the epiphysis where the bone forms an articulation with another bone. Perforating fibres
Periosteum part of bone features
dense, fibrous membrane covering bony surfaces and muscle
It contains the blood vessels and nerves that provide nourishment and sensation to the bone
What does the periosteum part of bone help with?
helps with blood supply to bones during development, remodeling and repair
The medullary cavity of bone features
Hollow cylindrical space within the diaphysis that contains fatty yellow bone marrow and numerous blood vessels
Endosteum part of the bone features
Thin fibrous membrane that lines the medullary cavity.
A single layer of osteoblasts cells and a small amount of connective tissue
What are the four types of cells present in bone tissue
Osteogenic cells, Osteoblasts, Osteocytes, Osteoclasts.
Osteoprogenic cells
Unspecified bone stem cells, undergo cell division, resulting cells develop into osteoblasts
Osteoblasts
Bone building cells
They synthesize and secrete collagen fibres
Osteocytes
Are mature bone cells
Exchange nutrients and wastes with the blood
Osteoclasts
Bone destroying cells
They are responsible for bone resorption (break down of extracellular matrix)
They also regulate bone calcium levels
Types of cartilage (3)
Hyaline cartilage- covers articular surfaces of bones
Elastics cartilage- Provides both strength and elasticity to certain parts of the body e.g ears
Fibrocartilage- Strong, rigid, dense. Provides tough material for e.g intervertebral discs and pubic symphysis
What does the bone’s flexibility depend on?
Collagen fibres
Spongey bone structure
-Located in the interior of the bone
-Covered by the protective compact bone
-Composed of lamellae which are arranged in irregular thin column called trabeculae
- Trabeculae contain bone marrow - red and yellow
- Helps bones resist stress without breaking
Compact bone structure (5)
-Composed of units called osteons
- Osteons consist of lamellae which have a common centre- central canal
- Between lamellae are small spaces called lacunae which contain osteoctyes
- Radiating in all directions from lacunae are canaliculi which join lacunae together
-The organization of osteons changes in response to the physical demands places on the skeleton
What is bone homeostasis?
-It is where injured bone is removed and is replaced by new tissue
-It is the balance between osteoclasts and osteoblasts
Repair process of a fractured bone (the phases)
Reactive phase
Reparative phase
Bone remodeling phase
Reactive phase
-Blood vessels are broken
-Haematoma forms
-Blood circulation ceases
-Swelling and inflammation occur in response to dead cells, producing debris
-Phagocytes begin to remove dead or damaged tissue
-Hours to days
Reactive -> reparative
Formation of soft callus which bridges broken ends of bone
Reparative phase
-Nearly healthy bone tissue osteoprogenitor cells develop into osteoblasts forming spongey bone trabeculae whihc join living and dead bone together
-Fibrocartilage coverted to spongey bone and the callus is now a bony ‘hard’ callus
-Days to weeks
Remodelling phase
-Dead portions of original bones are reabsorbed by osteoclasts
-Compact bone replaces spongey bone around border of fracture
-Usually a thickened surface remains as evidence of a fracture site
