Lecture 4

Question 1

5 bone shapes, and example of each?

Answer 1

Long - tibia, fibula,
Short - trapezium, capitate,
Flat - parietal, scapula,
Irregular - vertebrae,
Sesamoid - patella.

Question 2

What does periosteum mean?

Answer 2

Outer surface of bone.

Question 3

What does endosteum mean?

Answer 3

Inner surface of bone.

Question 4

What does diaphysis mean?

Answer 4

Long, thin middle portion of bone.

Question 5

What are epiphysis?

Answer 5

Widened ends of bone.

Question 6

Where is metaphysis?

Answer 6

Between epiphysis and diaphysis.

Question 7

6 functions of bone?

Answer 7

Support organs, 
protection, 
system of levers, 
store for minerals, 
haemopoiesis, 
endocrine organ?

Question 8

2 components of bone matrix?

Answer 8

Osteocollagen - organic component.

Hydroxy-apatite - mineral component.

Question 9

6 things forming osteocollagen?

Answer 9

Type I collagen,
bone proteoglycan,
osteocalcin, osteonectin, osteopontin (3 non collagenous proteins).
Hydroxy-apatite.

Question 10

What is collagen I biochemically speaking?

Answer 10

3 amino acid repeat. Gly-X-Y.

Question 11

What do osteoblasts do?

Answer 11

Synthesise bone matrix before priming it for subsequent mineralisation.

Question 12

What shape are they, and what do they contain?

Answer 12

Plump cuboidal.

Many organelles for synthesis and secretion of protein.

Question 13

Where are they found?

Answer 13

Form epithelioid layer on bone surface.

Question 14

What are osteocytes formed from, and when?

Answer 14

Formed from oustblasts when engulfed in bone matrix during apposition.

Question 15

Where are osteocytes found, and what do they rely on to survive?

Answer 15

Entombed within bone matrix.

Rely on canaliculi to bone surface and other entombed cells.

Question 16

What may osteocytes function in?

Answer 16

May function in regulation of calcium homeostasis and act as strain gauge for physical loads.

Question 17

What are osteoclasts (structurally), and what is their function?

Answer 17

Large multinucleate cells.

Resorption of bone.

Question 18

What are lining cells?

Answer 18

Osteoblasts which have completed phase of synthetic activity.

Question 19

Can lining cells reactivate?

Answer 19

Yes.

Question 20

2 types of bone matrix?

Answer 20

Woven or dense.

Question 21

What are osteons/Haversian systems?

Answer 21

Bone units in dense bone.

• Haversian canals,
• Volkmans canals,
• Lacunae,
• Canaliculi.

Question 22

What are Haversian’s and Volkman’s canals?

Answer 22

Haversian - longitudinal tunnels for blood vessels surrounded by dense osteocytes.
Volkman - Horizontal tunnels for blood vessels.

Question 23

What are lacunae and canaliculi?

Answer 23

Lacunae - caves in matrix occupied by osteocytes.

Canaliculi - Minute supply pipes between lacunae and canals.

Question 24

What type of growth does cartilage use?

Answer 24

Interstitial growth.

Question 25

What type of growth do flat bones use?

Answer 25

Appositional growth.

Question 26

What type of growth do long bones use?

Answer 26

Endochondral growth.

Question 27

Two types of ossification, and what type of growth is each?

Answer 27

Intramembranous - appositional.

Endochondral - endochondral.

Question 28

When is the epiphysis open, enabling growth to continue?

Answer 28

When cartilage growth rate exceeds rate of ossification.

Question 29

2 types of marrow and their function?

Answer 29

Red marrow - site of haematopoiesis.

Yellow marrow - fat store.

Question 30

Does fracture repair involve both peri- and endo- steum?

Answer 30

Yes.

Question 31

What repairs fractures?

Answer 31

Osteoblasts - migrate into crack, synthesising new bone.

Question 32

4 steps involved when osteoblasts synthesise new bone

Answer 32

Hematoma forms at site.
Primary callus forms from cartilage, splinting bone.
Spongy callus forms from spongy bone.
After 6-8 weeks, converted to dense bone, then remodelled to refine join.

Question 33

2 radiobiology techniques for checking up on bone?

Answer 33

X-ray imaging

Strontium 90.