Bone formation

Question 1

compact bone

Answer 1

dense/cortical bone. makes up 80% of bone mass.

Question 2

spongy bone

Answer 2

cancellous/trabecular. makes up 20% of bone mass. found internally to compact bone

Question 3

ligaments

Answer 3

type of joint that connects bone to bone. made of dense regular tissue.

Question 4

tendons

Answer 4

type of joint that connects muscles to bone. made of dense regular tissue.

Question 5

hyaline cartilage

Answer 5

covers the ends of bone, growth plates, and connects ribs to sternum

Question 6

fibrocartilage

Answer 6

absorbs shock. found in vertebrae, pubic symphysis, and knee joints

Question 7

bone functions

Answer 7

protection and support
movement
hemopoiesis (marrow - formation of blood cells)
storage of minerals and energy

Question 8

calcium and phosphate in bone

Answer 8

provide strength and rigidity, found in bone matrix

Question 9

lipids

Answer 9

provide energy, found in yellow marrow

Question 10

red bone marrow (myeloid)

Answer 10

contains reticular connective tissue, developing blood cells, and adipocytes. in children it’s found in spongy bone and medullary cavity. in adults it’s only found in spongy bone (and medullary cavity contains more adipocytes and yellow marrow)

Question 11

yellow marrow

Answer 11

contains reticular connective tissue and adipocytes. found in medullary cavities in adults

Question 12

osteoprogenitor cells

Answer 12

stem cells that mature into osteoblasts. found in periosteum and endosteum.

Question 13

osteoblasts

Answer 13

cells that synthesize and secrete initial, semisolid form of bone ground substance called osteoids. osteoblasts become trapped after calcification, and differentiate into osteocytes.

Question 14

osteocytes

Answer 14

maintain bone matrix and detect mechanical stress. stress causes osteocytes to signal osteoblasts to deposit more bone matrix.

Question 15

osteoclasts

Answer 15

phagocytic cells formed in red bone marrow. function in breaking down bone during resorption. found in the periosteum and endosteum.

Question 16

osteogenesis

Answer 16

ossification - the formation and development of bone that begins in embryo and continues through childhood.

Question 17

intramembranous ossification

Answer 17

forms within mesenchyme tissue. forms flat bones of skill and some facial bones.

Question 18

endochondral ossification

Answer 18

forms within hyaline cartilage. forms most bones of skeleton (vertebrae, limb bones, etc.)

Question 19

osteoid

Answer 19

collagen fibers and semisolid ground substance that makes up bone matrix and contributes to bone tissue flexibility.

Question 20

hydroxyapatite

Answer 20

crysal salts formed from calcium phosphate, calcium hydroxide, calcium carbonate, and ions like sodium, magnesium, sulfate, and fluoride. contribute to bone rigidity and compressional strength.

Question 21

mesenchyme

Answer 21

embryonic connective tissue that has mesenchymal cells and a lot of group substance. forms the flat bones of skull and some facial bones.

Question 22

first step of intramembranous ossification

Answer 22

during 8th week of embryonic growth, mesenchyme cells divide to form osteoprogenitor cells, which then form osteoblasts

Question 23

2nd step of oossification

Answer 23

osteoblasts form osteiod, creating ossification centers

Question 24

3rd step of intramembranous ossification

Answer 24

calcium salts deposited into osteoid solidify and cause calcification of osteoid

Question 25

4th step of intramembranous ossification

Answer 25

calcification results in woven bone (similar to spongy bone)

Question 26

5th step of intramembranous ossification

Answer 26

mesenchyme tissue surrounding woven bone thickens and forms periosteum

Question 27

6th step of intramembranous ossification

Answer 27

woven bone is remodeled into lamellar bone to form spongy and compact bone

Question 28

1st step of endochondral ossification

Answer 28

during 8-12th week of embryonic growth, chondroblasts secrete cartilage matrix and form a hyaline cartilage model. once trapped in cartilage, chondroblasts --> chondrocytes, perchondrium surrounds the cartilage.

Question 29

2nd step of endochondral ossification

Answer 29

within the diaphysis, the chondrocytes enlarge and resorb some of the surrounding cartilage matrix, forming large holes. holes trigger calcification, chondrocytes die due to lack of nutrients.

Question 30

3rd step of endochondral ossification

Answer 30

blood vessels grow into perichondrium, and stem cells within perichondrium divide to form osteoprogenitor cells, which then turn into osteoblasts.

Question 31

4th step of endochondral ossification

Answer 31

osteoblasts secrete osteoid around the calcified cartilagenous diaphysis, forming the periosteal bone collar.

Question 32

5th step of endochondral ossification

Answer 32

capillaries carrying osteoblasts form a periosteal band, which extends into the core of the cartilage diaphysis.

Question 33

6th step of endochondral ossification

Answer 33

osteoblasts produce osteoid, form the primary ossification center. bone formation extends in both directions toward the epiphyses.

Question 34

7th step of endochondral ossification

Answer 34

around the time of birth, hyaline cartilage in the center of the epiphyses calicifies and begins to degenerate.

Question 35

8th step of endochondral ossification

Answer 35

blood vessels and osteoprogenitor cells enter and bone is formed where the cartilage was, forming the secondary ossification centers.

Question 36

9th step of endochondral ossification

Answer 36

osteoclasts resorb some of the bone matrix within the diaphysis and create the medullary cavity.

Question 37

10th step of endochondral ossification

Answer 37

almost all cartilage has been replaced by bone except articular cartilage (on articular surfaces and at epiphyseal plates)

Question 38

final step of endochondral ossification

Answer 38

lengthwise, growth continues until epiphyseal plate solidifies to form epiphyseal line (last plates to ossify are in clavicle in late 20s).

Question 39

interstitial bone growth

Answer 39

the growth of long bones in length. occurs due to growth of cartilage within epiphyseal plates pushing the epiphyses away from each other.

Question 40

zone of resting cartilage

Answer 40

nearest to epiphysis, resemble mature hyaline cartilage

Question 41

zone of proliferating cartilage

Answer 41

chondrocytes undergo rapid mitotic cell division (forming into chondroblasts). newly formed chondroblasts form new cartilage.

Question 42

zone of hypertrophic cartilage

Answer 42

chondrocytes begin to enlarge and resorb cartilage

Question 43

zone of calcified cartilage

Answer 43

thinning cartilage between enlarged chondrocytes are calcified

Question 44

zone of ossification

Answer 44

calcified cartilage breaks, allowing entry of blood vessels and osteoprogenitor cells. new bone matrix is formed. nearest to diaphysis.

Question 45

appositional growth.

Answer 45

osteoblasts form external circumferential lamellae to increase diameter of bone. occurs deep to the periosteum. osteoclasts within the endosteum resorb bone matrix within medullary cavity, causing the cavity to widen.

Question 46

bone remodeling

Answer 46

dynamic process of continual addition of new bone tissue and removal of old bone tissue due to mechanical stress and hormones. 20% of the adult human skeleton is replaced yearly.