Lec 13 Bone Development

Question 1

What is an osteoblast?

Answer 1

cell that build bone; derived from mesenchymal stem cell in periosteum
secretes collagen and catalyzes mineralization

Question 2

What is an osteoclast?

Answer 2

multinucleated; much bigger than osteocyte; breaks down bone

Question 3

What is an osteocyte?

Answer 3

bone cell; senses mechanical force/stress on bone

Question 4

What type of collagen do osteoblasts secrete?

Answer 4

type 1 collagen

Question 5

What can you use to measure level of osteoblast activity?

Answer 5

• alkaline phosphotase

- osteocalcin

Question 6

What is effect of calcitonin on bone development?

Answer 6

inhibits osteoclasts

Question 7

What is effect of PTH on bone development?

Answer 7

activates osteoblasts

Question 8

What is effect of insulin on bone development?

Answer 8

activates osteoblast to stimulate matrix synthesis

Question 9

What is sclerostin?

Answer 9

protein that has inhibitor effect on osteoblastic activity; when osteocyte senses micro-crack –> stop producing sclerostin so build more bone

Question 10

Where does osteoclast reside?

Answer 10

at ruffled border

Question 11

What is RANK?

Answer 11

receptor on osteoclast precursor; binds RANK-Ligand [RANK-L] on osteoblast which activates it

Question 12

What is osteoprotegerin?

Answer 12

protein on osteoblast that blocks RANK so that osteoblasts can inhibit osteoclasts

Question 13

What is function of diaphysis?

Answer 13

thicker cortex, less trabicular bone

Question 14

What is function of metaphysis?

Answer 14

aids in stabilization

Question 15

How does bone grow in width?

Answer 15

resorption from middle; growth outside = maintains central hollow portion

Question 16

What do cement lines represent?

Answer 16

signs of where old surface of bone was before growth/remodelling

Question 17

What happens to cement lines in pagets?

Answer 17

become very irregular

Question 18

WHat is first step in skeletal morphogenesis?

Answer 18

cartilage formation

Question 19

What is endochondral ossification?

Answer 19

replacement of cartilage with bone; main way that skeletal forms

Question 20

When does epiphyseal growth plate remain open until?

Answer 20

until full maturity at age 19-20

Question 21

What is intramembranous ossification?

Answer 21

directly form bone from fibrous periosteal layer

Question 22

What type of bone makes up cortex?

Answer 22

mostly compact

Question 23

What type of bone makes up medullary?

Answer 23

cancellous/trabecullar bone –> have space that is occupied by fat/red marrow

Question 24

What parts of skeleton have marrow in adults?

Answer 24

only axial skeleton

Question 25

What is difference woven vs lamellar bone?

Answer 25

woven bone is immature; less organized; suggests pathology

lamellar = more stable, organized

Question 26

What type of joints are synovial joints?

Answer 26

diarthrosis

Question 27

What kind of ECM is secreted by chondrocytes?

Answer 27

made up of type 2 collagen + proteoglycans

Question 28

WHere is fibrocartilage located?

Answer 28

in intervertebral disc; meniscus

Question 29

Where is elastic cartilage located?

Answer 29

ear

Question 30

What are type A vs type B synoviocytes?

Answer 30

type A = phagocytic

type B = secrete synovial fluid