Bone and Cartilage

Question 1

two general types of bone

Answer 1

1. cortical compact bone (external)

2. cancellous spongey bone (internal - trabecular scaffolding)

Question 2

to microscopic types of bone

Answer 2

1. woven bone
   
   • irregular, rapid collagen deposition
   • more osteoclasts
   • present in foetus and fracture callus
2. lamellar bone
   
   • collagen slowly placed in parallel
   • fewer osteocytes
   • normal form in adults

Question 3

bone composition

Answer 3

60% inorganic (HA)
15% water
25% (90% collagen, then proteoglycans and glycoproteins for repair and immune response)

Question 4

structure of lamellar bone

Answer 4

• laid in concentric lamellae giving longitudinal columns
• in harversian system (around haversian canal) - one together called an osteon
• have lateral volkman’s canals (canaliculi) laterally joining haversian canals
• canals have blood vessels

Question 5

structure of cancelous bone

Answer 5

• network of thin trabeculae (made of lamelae)
• no haversian system obvious
• spaces filled with bone marrow
• thin bone for diffusing nutrients easily

Question 6

cells of bone?

Answer 6

osteoblasts

• on surface of bone
• place collagen matrix later mineralised by calcium salts

osteocytes

• osteoblasts caught in spaces (lacunae) of bone
• contact other osteocytes via canaliculi

osteoclasts

• within concavities of bone (howship’s lacunae)
• large, multinucleated, macrophage related cells
• resorb bone

Question 7

name of thin layer of bone between old bone and osteoblasts

Answer 7

osteoid

Question 8

what is apposition (bone lecture)

Answer 8

the balance of resorption and deposition of bone

Question 9

what is cartilage

Answer 9

avascular, unmineralised CT

Question 10

types of cartilage

Answer 10

1. hyaline cartilage (most widespread)
2. fibrocartilage (interspinal disks)
3. elastic cartilage (ears/epiglottic)

Question 11

what cells place cartilage

Answer 11

chondroblasts (if trapped in matrix = chondrocytes)

Question 12

what type of bone growth is for long bones

Answer 12

endochondral ossification

- cartilage forms model of bone the ossified

Question 13

what type of bone growth used for flat bones

Answer 13

intramembranous ossification

- no cartilage precursor, formed from scratch in CT

Question 14

how does long bone growth work

Answer 14

diaphyseal ossification occurs at side of epiphyseal plate where older cartilage lie (neck of bone side), in epiphyseal plate have cartilage proliferation, eventually this plate seals and bone can no longer grow in length (epiphyseal ossification?)