Bone Growth & Ossification

Question 1

skeleton is made of what before 6 weeks of development?

Answer 1

hyaline cartilage CT

Question 2

what is replaced with bone CT?

Answer 2

hyaline cartilage, mesenchyme

Question 3

mesenchyme

Answer 3

embryonic CT

Question 4

what remains of the hyaline cartilage in adults?

Answer 4

articular cartilage at ends of long bones

Question 5

ossification

Answer 5

replacement of other CT with bone CT

Question 6

2 types of ossification

Answer 6

intramembranous , endochondral ossification

Question 7

intramembranous ossification

Answer 7

bone CT replaces sheets of CT (mesenchyme)

Question 8

what is intramembranous ossification involved in developing?

Answer 8

skull, face, clavicle, mandible

Question 9

endochondral ossification

Answer 9

bones CT replaces hyaline cartilage CT

Question 10

what is endochondral ossification involved in developing?

Answer 10

limbs, vertebrae, hips

Question 11

basic process of ossification

Answer 11

1. other CT with some weakness is invaded with osteoblasts
2. osteoblasts and osteocytes rearrange calcified extracellular matrix and create patterns of ossification around blood vessels
3. bone starts to grow outwards towards site

Question 12

ossification centers

Answer 12

growth sites

Question 13

basic steps of intramembranous ossification

Answer 13

1. ossification centers begin to form within thickened regions of mesenchyme
2. ossification centers lay down osteoid to undergo calcification
3. woven bone begins to form and mesenchyme condenses to become periosteum
4. bone is remodeled to form lamellar bone

Question 14

osteoid

Answer 14

organic component of extracellular matrix

Question 15

basic steps of endochondral ossification

Answer 15

1. chondrocytes start to deteriorate in the center of the hyaline cartilage model
2. cavitation of hyaline cartilage within cartilage model
3. invasion of internal cavities by periosteal bud
4. formation of medullary cavity continues; secondary ossification centers in the epiphysis form
5. ossification in epiphysis; when completed hyaline cartilage remains only in epiphyseal plate and articular cartilage

Question 16

most common ossification for bone formation

Answer 16

endochondral ossification

Question 17

why does deterioration occur?

Answer 17

hyaline cartilage is too large to allow for diffusion of nutrients/gasses

Question 18

big takeaways of endochondral ossification

Answer 18

start with hyaline cartilage model of bone, bone collar formed around surface by cartilage, ossification begins within the diaphysis, secondary ossification centers in epiphysis which replace cartilage

Question 19

appositional growth

Answer 19

bone grows in diameter as new bone is added onto surface

Question 20

osteoclasts resorbs bone in

Answer 20

medullary cavity; enlargens cavity

Question 21

process of appositional growth

Answer 21

1. bone formation at surface of bone
2. ridges enlarge and create deep pocket; grow up ad around blood vessels
3. ridges meet and fuse trapping blood vessels within bone
4. bone deposition proceeds inward toward the blood vessel creating osteon shape
5. additional circumferential lamellae are deposited along perimeter increasing diameter
6. osteon is complete with central canal which contains blood vessel and second blood vessel become enclosed

Question 22

epiphyseal plate

Answer 22

area of cartilage in the metaphysis

Question 23

epiphyseal line

Answer 23

compact bone that marks end of epiphysis