MSK 1

Question 1

Osteoblast have what origin?

Answer 1

Mesenchymal origin

Question 2

Osteoblasts produce what?

Answer 2

Osteoid

Question 3

What bone cells initiate mineralization? And how?

Answer 3

Osteoblasts, by sending signals that control deposition of calcium and other minerals

Question 4

Osteocytes stimulate what?

Answer 4

Formation and Resorption of Bone

Question 5

Osteocytes play an important role in the homeostasis of what?

Answer 5

Calcium and Phosphorus

Question 6

___________ are VERY sensitive to changes in mechanical forces on bone and produce regulatory factors that direct mechanical forces on bone and produce regulatory factors that direct __________ and ________of bone of bone

Answer 6

Osteocytes, modelling and re‐modelling

Question 7

____________ have hematopoietic stem cell origin

Answer 7

Osteoclasts

Question 8

How are osteoclasts formed?

Answer 8

fusion of cells from monocyte/macrophage lineage (form multinucleated cells)

Question 9

What is the primary function of Osteoclasts?

Answer 9

Resorption of Bone

Question 10

How does osteclasts resorb bone?

Answer 10

produce acid hydrolases that dissolve and breakdown the inorganic and organic portions of bone

Question 11

What is Periosteum?

Answer 11

The outer lining of bone

Question 12

What makes up the extracellular matrix of bone? And are they organic or inorganic?

Answer 12

Osteoid (organic) and Calcium hydroxyapatite (CHAP) crystals (inorganic)

Question 13

Osteoid is made up of what? And which component is in greatest quantity?

Answer 13

Predominantly collagen fibers and glycoproteins.

Approximately 90% is type I collagen

Question 14

What are the Microscopic Classifications of bone?

Answer 14

Woven and Lamellar bone

Question 15

What is woven bone?

Answer 15

Immature bone that is present during fetal development and in the early stages of bone repair (active remodeling)

• A microscopic classification

Question 16

What is Lamellar Bone? How are collagen fibres arranged?

Answer 16

Mature bone: Collagen fibers are arranged in a parallel pattern

• A microscopic classification

Question 17

What are the Macroscopic Classifications of bone?

Answer 17

Compact Bones and Cancellous Bone

Question 18

Name 3 characteristics of compact bone

Answer 18

1. Compact bone is found in the cortex of bone or below articular cartilage.
2. Compact bone is HIGH DENSITY.
3. Compact bone can be either woven (if it’s immature or reactive) or lamellar (if it’s mature)

Question 19

Name 3 characteristics of cancellous bone

Answer 19

1. Cancellous bone is found in the
   medullary cavity of bones.
2. Cancellous bone is LOW DENSITY.
3. Cancellous bone can also be either mature (lamellar) bone or immature (woven) bone

Question 20

Is woven bone cancellous or compact bone?

Answer 20

NIETHER! cancellous or compact bone can be either lameler (mature) or wooden (immature)

Question 21

what is endochondral ossification ?

Answer 21

Bone develops from a hyaline cartilaginous model that is subsequently replaced by osseous tissue present in the ossification centers

Question 22

What is unique about intramembranous ossification?

Answer 22

There is no pre‐existing cartilaginous model

Question 23

Growth (lengthening) of the bone occurs on on what side of the bone?

Answer 23

metaphyseal side

Question 24

What is skeletal maturity?

Answer 24

Once the growth plate closes and there is no further increase in length of the bone

Question 25

What are the three zones of the growth plate?

Answer 25

1. The Reserve (or resting) Zone
2. The Proliferative Zone
   3.The Hypertrophic Zone

Question 26

What happens in the Reserve (or resting) Zone?

Answer 26

Where all the lazy‐ass, vacationing, do‐nothing chondrocytes hang out.

Question 27

What happens in the Proliferative Zone?

Answer 27

where chondrocytes multiply (proliferate), accumulate glycogen and produce the extracellular matrix of cartilage.

Question 28

In which zone of the physis does the bone lengthen?

Answer 28

Proliferative Zone

Question 29

What happens in the Hypertrophic Zone?

Answer 29

Where the chondrocytes mature and begin to mineralize the extracellular matrix of cartilage. After this they undergoe apoptosis

Question 30

During bone growth and development what happens at the metaphysis? What is the name of the specific area this happens?

Answer 30

the cartilaginous “blueprint” is transformed through endochondral ossification into bone

Happens in the area called the PRIMARY SPONGIOSA

Question 31

What happens at the secondary spongiosa?

Answer 31

Remodelling

Question 32

Bone is remodelled in response to ______

Answer 32

changing forces

Question 33

What happens in remodelling?

Answer 33

Life‐long process in which mature bone is removed from the skeleton and new bone tissue is formed

Question 34

How is it ensured that bone mass and shape remain constant during remodelling?

Answer 34

resorption must precede formation

Question 35

What are the five reactions to bone injury?

Answer 35

1. Necrosis
2. Altered trabeculae +/- reduced bone elongation
3. Changes in size, shape, and mass (modelling)
4. Production of new bone
5. Periosteal reaction

Question 36

What is a bone sequestrum?

Answer 36

forms when an area of devitalized (necrotic/mummified) bone is walled off by fibrous granulation tissue or reactive bone

Question 37

What is Wolff’s Law?

Answer 37

Adaptation of bone in response to use

Question 38

Decreased mechanical use causes what?

Answer 38

Increased resorption

Question 39

In normal remodeling there is no change in _____________

Answer 39

shape or amount of bone produced

Question 40

Excessive new bone formation is called?

Answer 40

hyperostosis