Forbes) questions with verified answers
# Osteoclasts > # Osteoblasts Ans✓✓✓ Bone removal exceeds bone
deposition, osteoporosis can result. Spongy bone (trabeculae)
reabsorbed before compact bone
#1 Step Ans✓✓✓ Fetal hyaline cartilage model develops (8-12 weeks).
Chondroblasts secrete cartilage matrix, and hyaline cartilage model
forms. Chondrocytes trapped within lacunae, perichondrium surrounds
cartilage
#1 Step Ans✓✓✓ Ossification centers form within thickened regions of
mesenchyme beginning @ eighth week of development.
Multiple ossification centers form within the thickened mesenchyme as
the number of osteoblasts increases
#1 Step Ans✓✓✓ Undifferentiated stem cells at the internal edge of
the perichondrium begin to divide
#2 Step Ans✓✓✓ Cartilage calcifies, periosteal bone collar forms.
Chondrocytes hypertrophy (enlarge), and cartilage matrix begins
calcification. Blood vessels grow toward cartilage and penetrate the
perichondrium around shaft. SC in perichondrium divide, form
osteoblasts. Perichondrium-> periosteum. Osteoblasts in internal layer
of periosteum secrete layer of osteoid around calcified shaft. Osteoid
hardens, forming periosteal bone collar around shaft
,#2 Step Ans✓✓✓ New undifferentiated SC and committed cells that
differentiate into chondroblasts are located at the periphery of the old
cartilage, where they begin to produce and secrete new cartilage matrix
#2 Step Ans✓✓✓ Osteoid undergoes calcification as calcium salts are
deposited onto the osteoid and they crystallize. When calcification
entraps osteoblasts w/in lacunae in the matrix, entrapped cells become
osteocytes
#3 Step Ans✓✓✓ Primary ossification center forms in diaphysis.
Remains of calcified cartilage serve as template where osteoblasts
produce osteoid, now called primary ossification center (first major
center of bone formation). Development extends towards both
epiphyses from the primary ossification center. Healthy bone CT
displaces calcified, degenerating cartilage in shaft.
#3 Step Ans✓✓✓ The chondroblasts, as a result of matrix formation,
push apart and become chondrocytes, with each occupying its own
lacunae. The cartilage continues to grow at the periphery as
chondrocytes continue to produce more matrix
#3 Step Ans✓✓✓ Woven bone and surrounding periosteum form.
Woven bone eventually replaced w/ lamellar bone. Mesenchyme that
surround woven bone thickens and forms periosteum. Additional
osteoblasts produced, new bv begin to branch. Calcified trabeculae and
intertrabecular spaces composed of spongy bone
,#4 Step Ans✓✓✓ Secondary ossification center form in the epiphyses.
Same process as one that formed primary ossification, but in epiphyses.
Hyaline cartilage in center of each epiphysis calcifies and begins to
degenerate. Epiphyseal bv and osteoprogenitor cells enter epiphyses.
Secondary ossification centers form as bone displaces calcified
cartilage, and osteoclasts resorb some bone matrix w/in diaphysis,
creating medullary cavity
#5 Step Ans✓✓✓ Bone replaces almost all cartilage, except the
articular cartilage and epiphyseal cartilage. By late development,
almost all hyaline cartilage is displaced by bone. Hyaline cartilage
remains as articular cartilage only on articular surface of each epiphysis
and at epiphyseal plates
#6 Step Ans✓✓✓ Lengthwise growth continues until the epiphyseal
plates ossify and form epiphyseal lines. Continues into puberty until the
epiphyseal plate develops into epiphyseal line, indicating adult length.
Most epiphyseal plates ossify and become epiphyseal lines between
ages 10-25
A. Articular Cartilage Ans✓✓✓ f: decrease friction, absorb shock
Acromegaly (Adults) Ans✓✓✓ High levels of HGH (after development),
results in enlarged hands, feet, jaw, organs
Cartilage continues growing, ossifies into bone
, Adult # of Bones Ans✓✓✓ 206
fetal= 275 (fuse together)
Aging of the Skeleton Ans✓✓✓
Amphiarthrotic Ans✓✓✓ Some movement
Ex: female coccyx (passageway for childbirth)
Aponeuroses Ans✓✓✓ Broad sheets of CT that attach adjoining
muscles or to broad areas of bone
Appendicular Osteopathology Ans✓✓✓
Appositional Bone Formation Ans✓✓✓ Increases diameter of long
bones
Appositional Ans✓✓✓ Increases diameter of long bones
Medullary cavity is increased (lamellae inside is broken as diameter
increases)
Arthritis Ans✓✓✓ Inflammation of a joint