Osseous Physiology Flashcards
Medullary cavity
“Marrow” cavity
Hollow cavity in diaphysis. Contains yellow bone marrow for adipose storage
Greenstick fracture
Usually seen in kids.
Partial fracture.
Once side broken, other side bent.
Osteoclasts
Cells that destroy bone as a natural part of growth and repair.
Haverian System
aka Osteon
Repeating units of all the components of compact bone around one central canal.
Includes canal, blood and lymph vessels, lacunas, canaliculi, oseocytes and concentric lamellae
Osteoblasts
Bone builders
Synthesize collagen fibres and initiate calcification.
Take Ca+ from blood for use in cells
Under what circumstances does ossification a occur?
- As an embryo (beginning in 6th week)
- Childhood and adolescence
- Normal remodelling of bone through adulthood
- Fracture repair.
Metaphyseal arteries/veins
Enter at the metaphysis to supply blood to the metaphysis and red bone marrow
Six key functions of the skeletal system:
- Support
- Protection
- Movement
- Control of mineral content (Ca+, P, Fe+)
- Hemopoesis
Storage of triglycerides.
Articular cartilage
Covers epiphysis. Reduces friction and allows movement at joints.
Most commonly composed of hyaline cartilage.
Pott’s fracture
Occurs only in legs. Closed fracture with damage to ankle articulation.
Stress fracture
Microscopic tears in the fissures of the bone.
Usually caused by repetitive and strenuous activities.
Diaphysis
Main portion of the bone (the shaft)
Development of Marrow Cavity
Part of endochondral ossification.
Occurs through osteoclast activity.
Osteocytes
Mature bone cells
Maintain daily metabolic activities of the bone
Perforating canals
aka Volkmann’s canals
Perpendicular canals that run superficial to deep.
Carry blood, lymphatic vessels, nerves, from periosteum.
Spongy bone
No osteons
Appears spongy due to lattice and irregular pattern of bone tissue distribution.
Greater blood supply than compact bone
Periosteum
The “skin” surrounding bones.
Made of irregular sense connective tissue.
Merges with tendons
Contains nerve endings which detect irregularities/pathologies
Osteogenic cells
AKA osteoprogenitors
Unspecified stem cells serviced from mesenchyme cells
Hypertrophic cartilage zone
In metaphysis, in between proliferating and calcified cartilage zone.
Large mature chondrocytes situated in columns.
X Rays
aka radiography
developed by William C. Roentgen
Electron beam shot through object and reflect off of hard objects. Use ionizing radiation.
Digital X-rays 50% more efficient and less harmful than traditional cathode tubes
What are the two types of canals found in compact bone?
Perforating (Volkmann’s) and Central (Haversian)
What are the two type of bone formation?
Intramembranous and endochondrial
Crystallized mineral salts in the ECM of the bone
Calcium phosphate Ca3(PO4)2 most abundant
Calcium hydroxide second most abundant.
What are the stages of Endochondral Ossification?
- Development of cartilage model
- Growth of cartilage model
- Development of primary ossification centre
- Development of the marrow cavity
- Development of secondary ossification centres
- Formation of articular cartilage and epiphyseal plate
Calcitriol
A form of Vitamin D which increases absorption of Ca+ from the GI tract.
Reparative Phase 2.0
Osteogenic cells become osteoblasts, which convert fibrocartilage into spongy bone. (bony callus formation)
Lasts 3-4 months
Epiphysis
Proximal and distal ends of bones.
Tend to have projections and fossa that articulate with other bones
What are some of the key roles of Ca+?
- act as a cofactor in numerous chemical reactions in the body
- deeply involved in blood clotting
- involved in muscle contractions
What are the stages of Intramembranous Ossification?
- Development of ossification centre
- - chemical messages cause mesenchymal cells to develop into osteoblasts, which secrete bone ECM - Calcification
- - osteoblasts –> osteocytes - Formation of trabelculae
- - matrix continues to harden and trabeculae form.
- - development of spongy tissue, red bone marrow - Development of periosteum
- - periosteum forms. Compact bone replaces spongy bone where appropriate.
Deposition
The process by which osteoblasts will lay down minerals and collagen fibres to create ECM
Two main portions of bone tissue
Spongy and compact
Concentric lamellae
Concentric rings surrounding each central canal.
AKA osteon
Factors that affect bone growth
Minerals (Ca+, P, F, Mg, Mn) Vitamins Vit A -- promotes osteoblasts Vit C -- collagen formation Vit D -- absorption of Ca+ Vit K & B12 -- build bone proteins Hormones (T3 & T4 from thyroid and IGF in response to hGH -- promote bone growth)
Proliferating cartilage zone
In the metaphysis, next to resting cartilage zone.
Contain large chondrocytes that replicate and divide to replace old/dying chondrocytes.
Appear like a stack of coins.
Epiphyseal arteries/veins
Enter at epiphyseal portion to supply blood to the epiphysis and red bone marrow
Development of secondary ossification centres.
Part of endochondral ossification
– epiphyseal place formed from penetration of epiphyseal arteries
Growth occurs outwards from epiphysis.
Cartilage continues to be converted into bone.