Cartilage and bone

Question 1

Cartilage

Answer 1

Modified connective tissue that provides support

Question 2

Condrocytes

Answer 2

located in lacunae

Question 3

Cartilage location in the body

Answer 3

Nose
intervertebral discs
associated with ribs
articular surface of bones
trachea/epiglottis/larynx/bronchi
pinna of ear
pubic symphysis

Question 4

Major functions of cartilage

Answer 4

supports soft tissue
forms articular surfaces of bones
growth in length of long bones

Question 5

Proteoglycans

Answer 5

composed of glycosaminoglycans (GAGs)

-linear polymers of repeating disaccharide units

Question 6

Principle GAGs in cartilage

Answer 6

Chrondroitin 4 and 6

Keratan sulfate

Question 7

Type II collagen

Answer 7

Forms a fibrillar scaffold

-determines tissue shape and produces tensile strength

Question 8

Perichondrium

Answer 8

formed from mesenchyme surrounding center of chodrification

Question 9

Two layers of perichondrium

Answer 9

Outer fibrous layer- type I collagen and Fibroblasts

Inner (chondrogenic) layer- chondroblasts

Question 10

Chondrocytes

Answer 10

produce and secrete ECM

end up in lacunae

Question 11

Cartilage is avascular

Answer 11

Receives nutrition from blood vessels of perichondrium

Question 12

Consequences of lack of blood vessels in cartilage

Answer 12

Size limitation
low metabolic rate
poor repair potential of tissue
systemic treatment with drugs difficult

Question 13

Hyaline cartilage

Answer 13

Most common form of cartilage
location- ventral ends of ribs
tracheal rings
larynx/bronchi/trachea
articular surfaces of joints
epiphyseal plate
nose

Question 14

Elastic cartilage

Answer 14

Where flexible support is need
external ear
epiglottis
several laryngeal cartilages
eustachian tube

ECM- contains numerous elastic fibers
-stains with orcein dyes

Question 15

Fibrocartilage

Answer 15

Location

• annulus fibrosus
• pubic symphysis
• a few tendons
• menisci of knee joint

ECM- increased amount of collagen causing eosinophilic appearance

No perichondrium associated with fibrocartilage

Question 16

Calcification of matrix

Answer 16

Hyaline cartilage is most susceptible

commonly occurs during aging

Question 17

Osteoarthritis

Answer 17

Gradual loss or change in physical properties of articular cartilage
commonly occurs during aging

Question 18

Chondroma

Answer 18

Benign tumors of cartilage

Question 19

Chondrosarcoma

Answer 19

Slow growing malignant tumors of cartilage

Question 20

Bone function

Answer 20

support fleshy structures
protects vital organs
harbors bone barrow
reservoir of Ca & phosphate
involved in body movement

Question 21

Periosteum

Answer 21

Specialized connective tissue surrounding bone

Question 22

Endosteum

Answer 22

specialized connective tissue with osteogenic potential

-lines inner surfaces of bone

Question 23

Does bone have blood vessels and nerves?

Answer 23

YES

Question 24

Spongy bone

Answer 24

3D lattice of branching trabecular

-form a system of interconnected spaces filled with bone marrow

Question 25

Compact bone

Answer 25

Composed mostly of ECM

-Lamella

Question 26

Lacunae

Answer 26

small cavities containing an osteocyte

Question 27

Canaliculi

Answer 27

small tubular channels

• communicate with canaliculi of adjacent lacunae
• essential for nutrition of osteocytes
• gap junctions allow ions and small molecules to pass from cell to cell

Question 28

Haversian canals

Answer 28

Contain small blood vessels, loose connective tissue, small nerves

run parallel to long axis of bone

Question 29

Volkman’s canals

Answer 29

Run at oblique angles to long axis of bone

-connect Haversian canals to one another and to free surface of bone

Question 30

ECM Osteoid

Answer 30

Type I collagen
GAGs and proteoglycans
responsible for toughness and resilience of bone

Question 31

Inorganic salts

Answer 31

thin plates or crystals of Ca phosphates

-responsible for hardness of bone

Question 32

Periosteum- 2 layers

Answer 32

Outer (fibrous) layer

Deeper (cellular) layer

Question 33

outer fibrous layer of bone

Answer 33

consists of dense irregular connective tissue
blood vessels which enter Volkmans canals
some collagen fibers anchor periosteum to bone

Question 34

Deeper cellular layer of bone

Answer 34

Osteogenic potential
Osteoprogenitor cells present in adults
-not actively making bone but can be reactivated

Question 35

endosteum

Answer 35

lines surfaces of vascular channels

covers the trabecular of spongy bone

Question 36

remodeling of bone

Answer 36

involves activity of osteoblast and osteoclasts
Spongy (trabecular) bone is more responsive to changes in load than compact (cortical) bone

In compact bone aversion systems are formed, resorbed and replaced throughout life

Question 37

Interstitial lamellae in compact bone

Answer 37

are persisting fragments of previous Haversian systems

Question 38

Osteoclasts morphology

Answer 38

Small pits on surface of bone

• Large cells
• Multinucleated
• eosinophilic cytoplasm
• ruffled border
• rich in mito and lysosomes
• attached to bone by podosomes which form tight seals

Question 39

Osteoclasts function

Answer 39

Break down of organic matrix by means of lysosomal hydrolytic enzymes

• dissolution of bone mineral by creating an acid environment
• –proton pump in membrane of ruffled border

Question 40

Osteoclast origin

Answer 40

fusion of monocytes

Question 41

osteoporosis

Answer 41

Estrogen levels fall @ menopause
-osteoclast activity enhanced
–bone resorption exceeds bone formation
results in skeletal fragility and increased susceptibility to fractures

Question 42

Osteopetrosis

Answer 42

Dense, heavy bones
bone formation exceeds bone resorption
-defective osteoclasts

Question 43

Osteogenesis imperfecta

Answer 43

Bone fragility

Osteoblasts produce insufficient type I collagen

Question 44

Rickets

Answer 44

softening of bones
Bone matrix does not calcify normally
-due to insufficient dietart Ca or failure to produce Vit D in children