intro to bones and tissues Flashcards
- How many bones in adults and children respectively?
206 (+ sesamoids)
270 children
- What is the Axial skeleton comprised of?
Cranium
Vertebral Column Rib Cage
- What is the Appendicular skeleton comprised of?
Pectoral girdle
Upper and Lower Limbs Pelvic Girdle
- What are the functions of the skeleton?
Supports body so you can stand up and not fall
Protection of your vital organs Movement - works with muscles so you can get around Mineral storage - Stores calcium and phosphate Produces blood cells
- What two ways do bones develop in utero?
Intramembranous Ossification - First occurs after conception → flat bones
mesenchymal cells -> bone
Endochondral Ossification - Begins 2 months into utero → long bones mesenchymal cells -> cartilage -> bone
- What are the different types of bone cells and what do they do?
Osteogenic cell - Bone ‘stem cell’
Osteocyte - 'Mature' bone cell, formed when osteoblast becomes imbedded in its secretions and they sense mechanical strain to direct osteoclast and osteoblast activity Osteoblast - Bone 'forming' Secretes 'osteoid' and catalyses mineralisation of osteoid Osteoclast - Bone 'breaking', dissolve and resorb bone by phagocytosis and are derived from bone marrow?
- Where are Osteogenic cells and Osteocytes found respectively?
Osteogenic cells - Deep layers of periosteum
Osteocytes - Entrapped in matrix
- Where are Osteoclasts and Osteoblasts found respectively?
Osteoblasts - Growing portions of bone, including periosteum and endosteum
Osteoclasts - Bone surfaces and at sites of old, injured or unneeded bone
- What are the organic and inorganic compositions of the bone matrix respectively?
Organic - 40%
Type 1 Collagen 90% Ground Substance 10% - Proteoglycans, Glycoproteins, Cytokine and Growth Factors Inorganic - 60% Calcium hydroxyapatite Osteocalcium phosphate
- Describe the structure of immature bone
Laid down in a ‘woven’ manner - relatively weak, disorganised
Mineralised and replaced by mature bone
- How would you describe the structure of mature bone?
Mineralised woven bone- organised
Lamellar (layer) structure - very strong
- Describe the structures of the individual mature bone types (Cortical and Cancellous)
Cortical
- ‘Compact’ - dense
- Suitable for weight baring
- has osteons, few spaces, and provides protection support and resisting stresses
Cancellous - 'Spongy' - honeycomb structure - Not suitable for weight baring
- Describe what an osteon is comprised of?
Concentric ‘lamellae’ around a central ‘Haversian Canal’
The 'Haversian Canal' contains blood vessels, nerves and lymphatics
- What are Lacunae?
Small spaces containing osteocytes
Tiny Canaliculi radiate from lacunae filled with extracellular fluid
- What are transverse perforating canals in the bone called?
Volkmans Canals
- What is the Physis ?
- What happens here during interstitial growth?
aka the physeal plate - the Zone of elongation in long bone, which contains hyaline cartilage
Epiphyseal side - Hyaline cartilage active and dividing to form hyaline cartilage matrix Diaphyseal side - Cartilage calcified and dies and then replaced by bone
- In the femur, where does growth occur?
Proximal physis around the hip and the distal physis around the knee
- What is appositional growth?
Deposition of bone beneath the periosteum to increase thickness
- How does appositional growth occur?
Ridges in periosteum create a groove for periosteal blood vessel
Periosteal ridges fuse, forming an endosteum-lined tunnel Osteoblasts in endosteum build new concentric lamellae inward toward center of tunnel, forming a new osteon Bone grows outwards as osteoblasts in periosteum build new circumferential lamellae Osteon formation repeats as new periosteal ridges fold over blood vessel
- How do you classify the 3 joints?
-
Fibrous - Sutures, Syndesmosis, Interosseous membrane
Cartilaginous - Synchondroses (Spine), Symphyses (pubic) Synovial - Plane, Hinge, Condyloid, Pivot, Saddle, Ball & Socket
- Describe the structure of the synovial joint capsules
Articular capsules (Outer) - keeps bones together structurally
Synovial membrane (Inner) contains synovial fluid
- What is the function of synovial fluid?
- How are synovial joints stabilised?
To reduce friction during movement
Bone surfaces - hip joint for example has a congruent bone surface so the ball and socket are very stable Ligaments prevent bones moving in excess and in extreme directions to keep the joint in tact
also muscles/tendons
- How does the shoulder joint’s stability compare with that of the hip?
Joint articulation- Mismatch-shallow socket, whereas the hip has a complete fit as it has a deep socket
Joint Capsule - Weak in shoulder, strong in hip Ligaments - Lacks strong ligaments in shoulder, strong network of ligaments in hip Muscles - Rotator cuff dependent with the shoulder but hip joint is supported by muscles in the hip Stabilty - Unstable in shoulder, more stable in hip Mobility - Extremely mobile in shoulder, less mobile in hip
- Which type of cartilage is found in intervertebral discs?
Fibrocartilage
- Which cartilage consists of chondrocytes and comprised of type II collagen interacting with proteoglycans and elastin?
- Which cartilage consists of chondrocytes and fibroblasts surrounded by type I collagen?
Elastic cartilage
Fibrocartilage
- Which cartilage consists of chondrocytes surrounded by territorial and interterritorial matrices containing type II collagen interacting with proteoglycans?
- Which cartilages are surrounded by perichondrium?
Hyaline cartilage
Hylaine and elastic cartilage
- Which cartilage is not surrounded by perichondrium?
- Are fibrocartilage, elastic and hyaline cartilage vascular or avascular?
Fibrocartilage
Avascular
Explain how intramembranous ossifiation leads to the development of mesenchymal to bone?
- Mesenchymal stem cells aggregate and form osteoblasts by differentiation
- Ossification centre forms
- Osteoblasts begin to secrete osteoid
- Peripheral mesenchymal cells continue to differentiate
- Osteoblasts secrete osteoid inwards towards ossification centre
- Osteoblasts become trapped in osteoid causing differentiation into osteocytes
- Osteoid calcifies and hardens after several days
- Osteoid continues to be deposited, assembles in random manner around embryonic blood vessels
- Finely woven trabeculae forms
- Mesenchyme begins to differentiate int periosteum
- Lamellar bone replaces woven bone at outer edge creating layers internal spongy bone remains
- Vascular tissue within trabecular spaces forms red marrow
- Osteoblasts remain on bone surface to remodel when needed
