15 Cartilage And Bone

Question 1

What do all types of cartilage have in common?

Answer 1

All have matrix containing proteolycan and hyaluronic acid

All have chondrocytes

Question 2

What are the 3 types of cartilage?

Answer 2

Hyaline
Elastic
Fibrocartilage

Question 3

What cells are present in hyaline cartilage?

Answer 3

Chondrocytes (present in isogenous groups)
Perichondrial cells develop into chondroblasts
Chondroblasts divide into chondrocytes

Question 4

What is hyaline cartilage’s role in Fetal development?

Answer 4

Precursor model of bones in fetus that develop by endochondral ossification

Question 5

Proteoglycan structure in cartilage ground substance

Answer 5

Similar to other connective tissues
About 100 hyaluronate proteoglycan aggregates per collagen fibril
Makes stiff gel-like substance

Question 6

Where is hyaline cartilage found?

Answer 6

Cartilage in nose
Articulate cartilage of joint
Costal cartilage
Larynx, trachea

Question 7

What is the perichondrium?

Answer 7

Covers margin of hyaline cartilage

Dense connective tissue

Question 8

Chondrocytes position

Answer 8

Lie in cartilage extracellular matrix which they produce and maintain

Question 9

What is appositional growth?

Answer 9

Growth from the periphery inwards

Question 10

What is interstitial growth?

Answer 10

Growth from the centre outwards

Question 11

Layers of tracheal wall (out to in)

Answer 11

Adventitious (areolar CT)
Hyaline cartilage
Submucosa with possible seromucous glands
Mucosa
Lumen of trachea lined with pseudostratified ciliated epithelium

Question 12

What cells are present in elastic cartilage?

Answer 12

Chondrocytes

Also contains elastic fibres

Question 13

Where is elastic cartilage found?

Answer 13

Pinna of ear
Eustachian tube
Epiglottis

Question 14

What cells are present in fibrocartilage?

Answer 14

Chondrocytes and fibroblasts
It is a combination of dense regular connective tissue and hyaline cartilage
No surrounding perichondrium

Question 15

Where is fibrocartilage found?

Answer 15

Intervertebral discs
Meniscus of knee joint
Pubic symphysis
Can act as shock absorber and resist to shearing forces

Question 16

Cartilage acts as template for bone formation

Answer 16

For developing long bones
Grow by endochondral ossification
Hyaline cartilage is model
Subsequently mineralises to form bone

Question 17

Growth plates

Answer 17

Present at femur head and end

Separates epiphysis from diaphysis

Question 18

Long bone development by endochondral ossification - embryo 5-6 weeks

Answer 18

Initial cartilage model

Miniature version of adult bone

Question 19

Long bone development by endochondral ossification - embryo 6-8 weeks

Answer 19

Collar of periosteal (compact) bone appears at sides of shaft

Question 20

Long bone development by endochondral ossification - fetus 8-12 weeks

Answer 20

Central cartilage calcifies
Nutrient artery penetrates, supplying bone-depositing osteogenic cells
Primary ossification centre formed

Question 21

Long bone development by endochondral ossification - postnatal

Answer 21

Medulla becomes cancellous bone
Cartilage forms epiphyseal growth plates
Epiphyses develop secondary centres of ossification at either end of bone

Question 22

Long bone development by endochondral ossification - prepubertal

Answer 22

Epiphyses ossify

Growth plates continue to move apart, lengthening bone

Question 23

Long bone development by endochondral ossification - mature adult

Answer 23

Epiphyseal growth plates replaced by bone

Hyaline articular cartilage persists

Question 24

Where are osteocytes?

Answer 24

In middle of bone

Question 25

Where are osteoblasts?

Answer 25

On edge of bone
When surrounded by new osteoid, becomes osteocyte
They secrete substance of bone

Question 26

Organic component of bone in matrix

Answer 26

Non-collagenous proteins stimulate osteoblasts to do their function
- Osteocalcin 
- Osteonectin
- Phosphoproteins
- Bone sialoprotein
- Bone morphogenic proteins
They resist pulling and tensing forces

Question 27

Osteoprogenitor

Answer 27

Undifferentiated cells - stem cells

Inner layer of endosteum and periosteum

Question 28

Osteoblast

Answer 28

Intermediate cells that cannot divide
Inner layer of endosteum and spicules
Lay down new bone

Question 29

Osteocyte

Answer 29

Terminally differentiated bone cell
Trapped within osteon
No longer lay down matrix - tissue maintenance

Question 30

Osteoclast

Answer 30

Large cells with many nuclei
Fused monocytes (WBCs)
On surface of cortical bone (endosteum)
Reabsorption of existing bone/breaks down bone

Question 31

Compact bone

Answer 31

Osteon - layers of bone around osteocyte, have blood vessels and nerves
Lamellar of compact mineralised collagen
Send out filipodia to communicate with other osteocytes
Haversian canal are vertical blood vessels
Volkmanns canal are horizontal blood vessels

Question 32

Osteoarthritis

Answer 32

Degeneration of bones
Mechanical failure of articular cartilage
Narrowing of joint space
Bone rubs against bone

Question 33

Rheumatoid arthritis

Answer 33

Autoimmune disease
Inflammation of synovial membrane
Thickening of joint capsule
Both bone and cartilage disintegrate

Question 34

Changes associated with rheumatoid arthritis

Answer 34

Osteoclasts degrade bone
Fibroblasts out down scar tissue
Macrophages digest bone
T cells recognise tissues as non-self