Lecture 17- Cartilage and bone

Question 1

What does appositional growth mean?

Answer 1

Growth from the periphery

Question 2

What does interstitial growth mean?

Answer 2

Growth from the centre

Question 3

What are the differences between hyaline, elastic and fibrous cartilage?

Answer 3

• Fibrocartilage is made up of mostly type I collagen whereas Hyaline and elastic are made up of type Type II
• Elastic cartilage also contains many elastic fibres
• Fibrocartilage contains fibroblasts and chondrocytes in the cartilage whereas Elastic and Hyaline only contains chondrocytes

Question 4

Where is Hyaline cartilage found?

Answer 4

• Articular ends of bones
• Larynx
• Trachea
• Lung
• Nose cartilage

Question 5

Where is fibrocartilage found?

Answer 5

• Meniscus
• Intervertebral disc
• Pubic symphysis
• Articular discs of sternoclavicular+ temporomanidubular joints

Question 6

What do the inorganic components of bone do?

Answer 6

• Mineralises the collagen matrix and makes it into bone

- Resists bending+ compression forces

Question 7

Where are the osteoprogenitor, osteocyte , osteoblasts and osteoclasts located on the bone?

Answer 7

• Inner layer of endosteum+ periosteum
• On the surface of cortical bone
• Inner layer of endosteum+ spicules
• Trapped within osteon

Question 8

Outline the process of endochondral ossification

Answer 8

1) Hyaline cartilage 5-6 weeks
2) Collar of periosteal bone appears in shaft (6-8 weeks)
3) Central cartilage calcifies. Nutrient artery penetrates and supplies osteogenic cells. Primary ossification centre (8-12 weeks)
4) Medulla becomes cancellous bone. Cartilage forms epiphyseal growth plate. Secondary centres of ossification epiphysis. (Post-natal)
5) Epiphyses ossify+ growth plates continue move apart, lengthening bone
6) Epiphyseal growth plates replaced. Hyaline articular cartilage persists. (mature adult)

Question 9

What is the difference between rheumatoid+ osetoarthritis and what are the effects of both?

Answer 9

Rheumatoid is caused by autoimmune disease whereby there is inflammatory cells invading the synovial membrane. Damage to bone+ articular cartilage whereas osteoarthritis is narrowing of joint space, bone rubs against bone, destroys hyaline cartilage.
Reduced smooth articlation+ growth of osteophytes- pain

Question 10

Where does mature bone carry on growing?

Answer 10

Epiphyseal growth plate- Fibroblasts differentiates into chondroblasts then into chondrocytes. In the zone of calcified cartilage the chondrocytes get destroyed+ degenerate and calcify. Osteoblasts mineralise the spicules left by the extracellular collagen matrix to form bone.

Question 11

Describe the microstructure of cortical and cancellous bone

Answer 11

Compact- Osteons, Haverson cancal’s going through it. It’s in layers (lamellae) Traps mineralised collagen and osteoblasts.Volkmann’s canal horizontal in between. Osteocytes sit in lacuane.
Spongy bone- Trabecullae with bone marrow in between and the blood vessels goes through

Question 12

Hyaline cartilage-trachea

Answer 12

C-shaped.
Surrounds mucosa
Reinforces trachea+ protects and maintains airway