Level 2 - Skeletal Development 2 Flashcards
The process of laying down new bone material by cells called osteoblasts. It is synonymous with bone tissue formation
Ossification (osteogenesis)
What are the 2 processes resulting in the formation of normal, healthy bone tissue
Intramembranous ossification
Endochondral ossification
-occurs with a connective tissue membrane, no cartilage present
Ex. Flat bones in skull, clavicle, mandible
Intramembranous ossification
-bone formation from cartilage
Ex. Long bones
Endochondral ossification
Where is the primary ossification Center always?
The shaft of a long bone
Where is the secondary ossification centre always?
In the epiphysis of a long bone
What 4 layers is the epiphyseal plate made of?
-resting cartilage cells
-zone of proliferation
-zone of hypertrophy
-zone of calcification
Point of attachment joining the epiphysis to the shaft
“Resting” cartilage cells
Cartilage cells undergoing active mitosis, which causes the layer to thicken and the plate to increase in length
Zone of proliferation
Older, enlarged cells undergoing degenerative changes associated with calcium deposition
Zone of hypertrophy
Dead or dying cartilage cells undergoing rapid calcification. Therefore, creating new bone tissue and bone grows in length
Zone of calcification
Where does bone growth occur?
Added bone (new growth) is closer to the shaft side
What is the process called where mature bone tissue is removed form the skeleton?
Bone resorption
A life long process where mature bone is removed from skeleton and new bone tissue is formed
Bone remodeling
T/F
Bone remodeling also responds to functional demands of the mechanical loading
True
As a result, bone is added where needed and removed where not needed
T/F
In the first year of life, almost 100% of the skeleton is replaced
True
How much of the skeleton is replaced each year in adults?
10%
T/F
An imbalance in the regulation of bone remodelling (bone resorption and bone formation) may result in metabolic disease, such as osteoporosis
True
T/F
Bones grow in length and diameter by the combined action of osteoclasts and osteoblasts
True
-osteoclasts enlargement the diameter of the medullary cavity and demineralize the tissue
-osteoblasts from the periosteum build new bone around the outside of the bone
T/F
Mechanical stress strengthens bones (physical activity)
True
T/F
Remodeling activity is important for blood calcium levels to be maintained as well as permitting bone growth in length and diameter, and the changing size of the medial part cavity
True
What causes a fracture hematoma?
Fracture tearing and destroying blood vessels that carry nutrients to osteocytes
Blood clot occurring immediately after the fracture, which is then absorbed and replaced by callus
Fracture hematoma
Special repair tissue that binds the broken ends of the fracture together
Callus
-avascular connective connective tissue
-has flexibility of firm plastic
-no canal system or blood vessels
-chondrocytes receive oxygen and nutrients by diffusion
Cartilage
Fibrous covering of cartilage
Perichondrium
Why do cartilage types differ?
-amount of matrix present
-amount of elastic and collagenous fibers
-most common type of cartilage
-covers particular surfaces of bones
-forms the costal cartilages, cartilage rings in trachea, tip of nose
-forms from special cells in chondrificstion centers, which secrete matrix material
-chondrocytes are isolated into lacunae
Hyaline cartilage
-large number of elastic fibers confers elasticity and resilience
-forms eat, epiglottis, eustachian tubes
Elastic cartilage
-small quantities of matrix and abundant fibrous elements
-strong and rigid
-occurs in pubic symph. And intervertebral disks
Fibrocartilage
-tough rubber like nature permits cartilage to sustain great weight or serve as shock absorber
-strong yet pliable support structure
-permits growth in length of long bones
Functions of cartilage
-cartilage cells divide and secrete additional matrix
-seen during childhood and early adolescence while cartilage is still soft and capable of expansion from within
Interstitial or endogenous growth
-chondrocytes in the deep layer of the perichondrium divide and secrete matrix
-new matrix is deposited on the surface, thereby increasing its size
-unusual in early childhood, but once initiated continues throughout life
Appositional or exogenous growth
When is the Skelton fully ossified by?
Mid 20s
*soft tissue may continue to grow; ossifies more slowly
The skeleton comprises of approximately how much compact and cancellous bone?
80% compact
20% cancellous
Mature bone cells
Osteocytes
T/F
Trabeculae provide the internal support structure of bone and are aligned along the direction of forces to provide tensile and compressive strength
True
Process in which the red bone marrow produces red and white blood cells
Haematopoiesis
T/F
Blood vessels do not enter or exit the bone at surfaces covered by articular hyaline cartilage
True
