Bone Formation Flashcards
Intramembranous ossification
replaces mesenchyme
Endochondral ossification bone’s
preceded by cartilage model
What type of bone is replaced before secondary bone in both intramembranous and endochondral ossification
Woven bone appears first
Intramembranous bone formation is for what type of bone
Flat bones, pelvis, ribs, sternum, scapula
What type of cells differentiate into osteoblasts Paraxial mesoderm
describe process of intrmembranous bone ossification mesenchyme cells differentiate into osteoblasts secreting osteoid at multiple ossification centers, osteoid calcifies, fusion of ossification centers
Where do osteoblasts secrete osteoid
ossification centers
what happens to the mesenchyme that do not form bone
these become the bone marrow and periosteum
Compact bone surrounds_____
Spongy bone
Endochondral ossification is for what types of bones
Most bones, long bones, vertebrae,
Endochondral bone formation permits
Permits functional stress
what type of cartilage makes the model to be replaced in endochondrlal ossification
hyaline type II cartilage???? not sure that this is correct
Explain endochondrla ossification
Mesenchyme differentiates into cartilage surrounded by perichondrium, chondrocytes resorb cartilage which begins calcifying, chondrocytes die leaving hard matrix, Concurrently vessels are invading perichondrium. Progenitor cells differentiate into osteoblasts and perichondrium is now periosteum. Osteoblasts form periosteal bone collar. Primary ossification center forming with vessels and osteoblasts penetrating diaphysis, osteoid hardening and cartilage degenerating. Secondary ossification centers form in the epiphysis. Bone replaces cartilage via osetoblasts everywhere except articular surfaces & ends of diaphysis (epiphyseal growth plates). Bone inside diaphysis removed by osteoclasts forming medullary cavity.
periosteum, what did it differentiate from
from perichondrium surrounding cartilage model
What forms the periosteal bone collar
Osteoblasts
what differentiated into osteoblasts
progenitor cells
periosteal bone collar forms around forms around the ______
diaphysis in endochondral ossification
Primary ossification center forming when
with vessels and osteoblasts penetrating diaphysis, osteoid hardening and cartilage degenerating this is formed
where do secondary ossification centers form
in the epiphysis
Bone replaces cartilage everywhere except
articular surfaces & ends of diaphysis
medullary cavity is formed by
Bone inside diaphysis removed by osteoclasts forming this..
Cartilage repair has rich capacity for repair T/F
False, poor capacity because of poor vascular supply
In cartilage repair, why is the presence of the perichondrium important?
If this is present, then the precursor cells differentiate into chondroblasts producing more matrix
Perichondrium
what first surrounds developing bone in beginning of endochondral bone growth before the bone collar and what eventually becomes the periosteum.
what forms bony callus
osteoprogenitor cells laying new primary bone
soft callus is a
fibrocartilage
Epiphyseal growth plates composed of
hyaline cartilage type II
How does longitudinal growth occur
epiphyseal growth plates, cartilage proliferates and replaced by bone
What are the 5 zones of epiphyseal plate
Resting zone, proliferative zone, hypertrophic zone, calcified cartilage zone and ossification zone
What zone is near the epiphyseal end? by diaphysis?
resting zone ossification zone
Resting zone
Typical hyaline cartilage
Proliferative zone
chondrocytes divide into columns
hypertrophic zone
chondrocytes grow in size
calcified cartilage zone
Cartilage calcifies, chondrocytes apoptosis
Ossification zone
osteogenic cells & vessels invade, osteoblasts secrete osteoid over calcified cartilage and osteoclasts resorb cartilage
during growth epiphyseal growth plate changes in thickness T/F
F, long bone grows in length only
Eventually epiphyseal plate is replaced with bone T/F
True
when is the epiphyseal plate eliminated
different time but usually 25yrs.
Bone turnover involves
resorption & laying down new bone
bone growth =
rate bone formation > bone loss
Why do bones have an excellent capacity for repair?
due to extensive vasculature and osteoprogenitor cells in endosteum, periosteum
Endosteum
a thin vascular membrane of connective tissue that lines the surface of the bony tissue that forms the medullary cavity of long bones.
Osteocytes lie within
Lacunae
Process of fracture repairs
Blood clot forms, (hematoma), bones resorbed (osteoclasts), fibrocartilage-like soft callus formed, osteoprogenitor cells lay primary bone forming bony callus,
blood clot in bone repair
hematome
soft callus is formed from
bone resorption via osteoclasts into this
