Osteogenesis and Joints

Question 1

In intramembranous bone formation, what do mesenchymal cells differentiate into?

Answer 1

osteoblasts

Question 2

In intramembraneous bone formation, what do osteoblasts secrete?

Answer 2

osteoid; it traps some of the osteoblasts.

Question 3

What is another term for trapped osteoblasts in the osteoid?

Answer 3

osteocytes

Question 4

In intramembranous bone formation, what do the osteocytes form?

Answer 4

A functional syncytium

Question 5

In intramembranous bone formation, what ion causes mineralization?

Answer 5

calcium ions

Question 6

What does osteoid include?

Answer 6

collagen I and non-collagen proteins.

Question 7

What do primary ossification centers become?

Answer 7

a trabecula.

Question 8

What do numerous trabeculae fuse together to become?

Answer 8

spongy bone

Question 9

In intramembranous bone formation, what is the initial type of bone formed?

Answer 9

woven bone; its collagen fibers are arranged randomly.

Question 10

What type of bone includes aligned collagen fibers?

Answer 10

lamellar bone

Question 11

In endochondral bone formation, what is cartilage replaced by?

Answer 11

bone

Question 12

In endochondral bone formation, what do chondrocytes release?

Answer 12

vascular endothelial growth factor

Question 13

In endochondral bone formation, when do chondrocytes apoptose?

Answer 13

After vessels have formed

Question 14

In endochondral bone formation, what cells used calcified strands as substrates for deposition of osteoid?

Answer 14

osteoblasts

Question 15

Where does secondary ossification occur?

Answer 15

in the epiphyses

Question 16

What are the epiphyses and diaphyses separated by?

Answer 16

A growth plate

Question 17

What are the four zones of the growth plate?

Answer 17

reserve zone, proliferative zone, hypertrophic zone, vascular invasion zone

Question 18

What occurs in the reserve zone?

Answer 18

primitive hyaline cartilage is found; it is responsible for the growth in length of bone and erosion/deposition process advances.

Question 19

What is the epiphysis made of?

Answer 19

hyaline cartilage

Question 20

What occurs in the proliferative zone?

Answer 20

chondrocytes mitotically divide and form stacks parallel to cartilage.

Question 21

What occurs in the hypertrophic zone?

Answer 21

chondrocytes apoptose and calcification occurs

Question 22

What occurs in the vascular invasion zone?

Answer 22

vessels invade the bone.

Question 23

Where does ossification first occur?

Answer 23

The diaphysis (midsection) of a long bone

Question 24

During ossification, what lays periosteal bone on top of endochondral bone?

Answer 24

perisoteum

Question 25

Each epiphysis plate is separated from the diaphysis by what?

Answer 25

a plate of hyaline cartilage

Question 26

During endochondral bone formation, what is the role of the osteoclast?

Answer 26

to break down bone in the center of diaphysis and form a medullary cavity.

Question 27

During endochondral bone formation, cartilage is continually added to what end of the ephiphyseal plate?

Answer 27

distal end

Question 28

During endochondral bone formation, cartilage is replaced by bone at what end?

Answer 28

proximal end; this increases bone length.

Question 29

What kind of cartilage remains at either end of the bone?

Answer 29

articular cartilage

Question 30

What are the 3 zones of the epiphyseal plate?

Answer 30

zone of proliferation, hypertrophy/calcification and ossification

Question 31

What is proliferation stimulated by?

Answer 31

Indian hedgehod (ihh); it also prevents hypertrophy of chondrocytes.

Question 32

What is a joint?

Answer 32

Where two bones come together

Question 33

What are the 3 major classes of joints?

Answer 33

cartilaginous, fibrous and synovial

Question 34

What are the types of cartilaginous joints, and what are they composed of?

Answer 34

symphysis (fibrocartilage), synchondrosis (hyaline cartilage)

Question 35

What are examples of symphysis and synchondrosis joints

Answer 35

intervertebral discs, pubic symphsis (symphysis); epiphyseal plate and first sternocostal joint (synchondrosis)

Question 36

What are the types of fibrous joints, and what are they composed of?

Answer 36

suture, gomphosis and syndesmosis; collagenous or elastic fibrous CT

Question 37

What are examples of suture, gomphosis and syndesmosis joints?

Answer 37

calvaria (suture), teeth in socket (gomphosis), membrane of fibia and tibia (syndesmosis)

Question 38

What is a feature of synovial joints?

Answer 38

they are surrounded by a fluid-filled capsule.

Question 39

What are the 3 types of synovial joints?

Answer 39

monaxial, biaxial and triaxial

Question 40

What are examples of the 3 types of synovial joints?

Answer 40

hinge/knee (monaxial), finger/atlantooccipital/saddle (diaxial); ball-and-socket (triaxial)

Question 41

What type of cartilage is found in synovial joints?

Answer 41

articular (hyaline) cartilage