Lecture 10: Bone and cartilage

Question 1

After M-CSF is released by osteoblasts, it binds ____ which causes

Answer 1

M-CSF receptor on monocyte, which now becomes a macrophage and expresses RANK

Question 2

What does RANK do after being expressed on macrophage

Answer 2

Binds RANKL on osteoblast and the macrophage becomes a multinucleated immature osteoclast

Question 3

Osteoclasts secrete

Answer 3

Cathepsin K

H+ Cl- ions

Question 4

What happens when osteoblasts secretes osteoprotegerin

Answer 4

Osteoprotegerin binds RANKL with higher affinity than RANK
This inhibits maturation of osteoclasts
PTH blocks synthesis of osteoprotegerin

Question 5

Woven bone

Answer 5

Occurs during bone development or repair
Produced rapidly
Haphazard collagen foundation
Less structural integrity

Question 6

PTH stimulates

Answer 6

Differentiation of monocyte precursors to form osteoclasts

formation of ruffled borders on osteoclasts

Question 7

Fibrocartilage characteristics

Answer 7

Increased collagen
Reduced cellularity compared to hyaline
No perichondrium
Type I collagen
Single sparse chondrocytes

Question 8

Fibrocartilage location

Answer 8

Intervertebral discs
Pubic symphysis
Insertion of some tendons/ligaments
Closely associated with dense CT or hyaline cartilage

Question 9

Sharpeys fibers

Answer 9

Collagen fibers derived from the outer layer of the periosteum, projecting into the outer circumferential lamellar system

Question 10

Matrix of bone consists of

Answer 10

Organ component osteoid

Inorganic component hydroxyapatite (35-65% of matrix)

Question 11

Components of cartilage matrix

Answer 11

Collagen type II (type I in fibrocartilage)
Hyaluronic acid
Chondroitin, keratin and heparin sulfate
Glycosaminoglycans

Question 12

Osteocytes

Answer 12

Maintain bone matrix

Help control calcium/phosphate levels in matrix

Question 13

Elastic cartilage chondrocytes

Answer 13

Chondrocytes are mostly located singly

Question 14

Spongy bone

Answer 14

Trabecular/cancellous bone

3-D lattice of branching, bony spicules intertwined to form trabeculae surrounding bone marrow spaces in long/flat bones

Question 15

Osteoblasts are derived from and give rise to

Answer 15

Osteoprogenitor cells

Osteocytes

Question 16

What happens when PTH binds receptor on osteoblast

Answer 16

Osteoblast is stimulated to synthesize & express M-CSF and RANKL
(Monocyte-Colony stimulating factor)

Question 17

Function of H+ and Cl-

Answer 17

Dissolve the inorganic matrix

Question 18

Osteocalcin function

Answer 18

High binding affinity for hydroxyapatite

Question 19

Calcitonin function

Answer 19

Reduces bone resorption

Question 20

Vitamin D-3 function

Answer 20

Regulates expression of osteocalcin

Question 21

Osteoblasts

Answer 21

Secrete bone matrix

Secrete collagen and catalyze mineralization

Question 22

Osteoclasts are derived from

Answer 22

Monocyte lineage

Question 23

Hyaline cartilage strength

Answer 23

Solid but flexible

Question 24

Territorial matrix content

Answer 24

High glycosaminoglycan content, low collagen content

Question 25

Hyaline cartilage found in

Answer 25

External auditory meatus
Larynx
Tracheal cartilages
Bronchial cartilages
Fetal long bones
Articular ends of bones

Question 26

Elastic cartilage found in

Answer 26

Auricle

Epiglottis

Question 27

Function of Cathepsin K

Answer 27

Lysosomal protease involved in bone resorption and remodeling that can catabolize elastin, collagen and gelatin (organic matrix)

Question 28

Major protein products of osteoblasts

Answer 28

Type I collagen
Osteocalcin
Osteonectin
Osteopontin
Osteoprotegrin
RANKL