[2] Lecture 12: Bone And Cartilage

Question 1

3 major types of cartilage:

Answer 1

Hyaline
Elastic
Fibrocartilage

Question 2

How is cartilage types discerned?

Answer 2

Based on their matrix

Question 3

What type of collagen is present in cartilage extracellular matrix?

Answer 3

Type II collagen

EXCEPT: fibrocartilage possesses type I collagen

Question 4

Most common cartilage
Contains type II collagen
Surrounded by perichondrium 
Chondrocytes found in groups
Appositional and interstitial growth

Answer 4

Hyaline cartilage

Question 5

Where is hyaline cartilage located..examples:

Answer 5

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

Question 6

Type II collagen 
Surrounded by perichondrium 
Yellow color d/t elastic fibers
Chondrocytes mostly located singly
More flexible..

Answer 6

Elastic cartilage

Question 7

Where is elastic cartilage located..ex:

Answer 7

Auricle (pinna) of the ear

Epiglottis

Question 8

Increased collagen in matrix
Type I collagen
No perichondrium 
Fibrous texture
Single sparse linear Chondrocytes

Answer 8

Fibrocartilage

Question 9

Where is fibrocartilage found…ex:

Answer 9

Intervertebral discs
Pubic symphysis
Insertion of some tendons/ ligaments
Asso. W/ dense CT or hyaline cart.

Question 10

Why is fibrocartilage no considered a cartilage by some>?

Answer 10

No perichondrium

Question 11

Cells in cartilage:

Answer 11

Chondroblasts

Chondrocytes

Question 12

Components of cartilage extracellular matrix (ECM):

Answer 12

• Collagen fibers (II-hyaline and elastic/// I for fibrocartilage)
• Amorphous ground substance

Question 13

Lay down cartilage matrix and become Chondrocytes

Answer 13

Chondroblasts

Question 14

Maintain cartilage matrix

Answer 14

Chondrocytes

Question 15

Pockets w/in the matrix where the chondroblasts and Chondrocytes are found

Answer 15

Lacunae

Question 16

Layers of perichondrium:

Answer 16

Outer fibrous layer [contains fibroblasts]

Inner chondrogenic layer [chondroblasts become chondrocytes]

Question 17

groups of 2-8 Chondrocytes occupying the same lacunae as a result of mitotic division

Answer 17

Isogenous groups- these separate as they lay down matrix of their own

Question 18

Composed of high glycosaminoglycan content but low collagen content

Surrounds each chondrocyte

Answer 18

Territorial matrix

Question 19

Low glycosaminoglycan content but high collagen content

Surrounds territorial matrix

Answer 19

Inner-territorial matrix

Question 20

This is circumscribed by moderately stained territorial matrix and less intensely stained interterritorial matrix

Answer 20

Pericellular matrix

Question 21

Bone while developing and during repair

Produced rapidly, haphazard collagen foundation, less structural integrity

Answer 21

Woven bone

Question 22

How do bones grow?

Answer 22

Appositional growth of a hyaline cartilage model.

Question 23

Matrix of bone components:

Answer 23

Osteoid-organic

Hydroxyapatite-inorganic

Question 24

How is bone classified?

Answer 24

Arrangement of the matrix

Question 25

3D lattice of branching, bony spicules intertwined to form trabecular surrounding the bone marrow spaces in the long bones and flat bones.

Answer 25

Spongy bone OR: trabecular / cancellous

Question 26

Lacks cavities and forms a dense plate on the outside of long bones

Answer 26

Compact or lamellar bone

Question 27

Describe Osteon/canaliculi system

Answer 27

Osteocytes are found between lamellae in lacunae. They're connected to each other and Haversian canal via canaliculi this forms Osteon

Question 28

Secretes bone matrix, collagen and catalyzes mineralization

Answer 28

Osteoblast

Question 29

Maintains bone matrix and helps to control calcium and phosphate levels in matrix Derived from osteoblasts-trapped in matrix they secrete

Answer 29

Osteocyte

Question 30

Remodels bone through bone resorption-microfractures and such

Answer 30

Osteoclast

Question 31

Stem cells which in the adult are described as bone lining cells. In adult, found in inner portion of the periosteum, endosteum, and lining vascular canals of compact bone. -derived from mesenchyme of the embryonic Somite [sclerotome]

Answer 31

Osteoprogenitor cells

Question 32

Derived from osteoprogenitor cells And gives rise to osteocytes Regulates expression of osteocalcin

Answer 32

Osteoblasts

Question 33

Derived from monocytes lineage- which is derived from the monocyte precursors in Bone marrow

Answer 33

Osteoclast

Question 34

What does ARF stand for?

Answer 34

Activation-resorption-reversal-formation Active during adult remodeling and during development

Question 35

Primary regulator of bone turnover

Answer 35

Parathyroid hormone

Question 36

At low PTH levels,

Answer 36

Bone formation by osteoblasts is stimulated

Question 37

At high PTH levels,

Answer 37

Osteoblasts are stimulated to release osteoclast-differentiation factors

Question 38

What stimulates the differentiation of monocyte precursors to for osteoclasts?

Answer 38

PTH, also forms ruffled borders on osteoclasts

Question 39

What would elevated PTH levels cause?

Answer 39

Eroded bone and fibrosis of the resulting spaces (osteitis fibrosa)

Question 40

Steps of osteoblasts regulating osteoclasts

Answer 40

1-PTH binds to receptors on the osteoblast 2-Osteoblast is stimulated to synthesize M-CSF and RANKL 3-osteoblast releases M-CSF 4-M-CSF binds to the M-CSF receptor on the monocyte that just happened to be close. 5-Monocyte is now macrophage and expresses RANK 6-RANK binds to RANKL-coupling osteoblast and macrophage 7-Macrophage becomes a multinucelated immature osteoclast

Question 41

Secretes osteoprotegerin

Answer 41

Osteoblast

Question 42

What blocks RANKL site from macrophages to prevent formation of more osteoclasts?

Answer 42

Osteoprotegerin occupies RANKL when there is NO PTH present

Question 43

PTH blocks X the synthesis of what in osteoblasts?

Answer 43

Osteoprotegerin

Question 44

Acts to reduce bone resorption

Answer 44

Calcitonin

Question 45

2 major products secreted by osteoclasts:

Answer 45

Cathepsin K H+ Cl- ions

Question 46

A lysosomal protease involved in bone remodeling and resorption that can catabolism elastin, collagen, and gelatin [organic matrix]

Answer 46

Cathepsin K

Question 47

secreted by osteoclast to Dissolves the inorganic matrix

Answer 47

H+Cl- ions