Basic Science

Question 1

What are the 3 main functions of bone?

Answer 1

1. Haemopoetic
2. Calcium Homeostasis
3. Mechanical Support

Question 2

How can bone be classified?

Answer 2

According to anatomy and structure

Question 3

How can bones be divided anatomically

Answer 3

Long Bones
Flat Bones

Question 4

What are the three main sections of a long bone?

Answer 4

Epiphysis
Metaphysis
Diaphysis

Question 5

Give some examples of flat bones

Answer 5

Pelvis
Skull
Scapula
Clavicle

Question 6

How can the structure of bone be further subdivided

Answer 6

Macroscopic
Microscopic

Question 7

What are the two types of macroscopic bone

Answer 7

Woven - immature
Lamellar - mature

Question 8

What are the features of woven bone? (3)

Answer 8

Isotropic - Behaves the same regardless of direction of load applied to it
High turnover
Lacks mechanical properties

Question 9

Give some examples of woven bone lacking mechanical properties of mature bone (3)

Answer 9

1. Fracture callus
2. Embryonic long bone formation
3. Pathological bone

Question 10

What are the features of lamellar bone (3)

Answer 10

1. Anisotropic - behaves differently according to direction of load applied to it
2. Slow turnover
3. Stronger mechanically

Question 11

How much of the skeleton does cortical bone make up and what are its two main features

Answer 11

80%
Slow turnover
Higher Young’s modulus

Question 12

What is the microscopic unit of cortical bone

Answer 12

Osteon

Question 13

Describe the structure of an osteon

Answer 13

Concentric rings (lamellae) of type 1 collagen arranged around a central neurovascular canal (Haversian canal)

Question 14

What connects the intravascular supply of an osteon to the extravascular supply?

Answer 14

Volkmann’s canal (run perpendicular)

Question 15

What separates osteons and what is their significance

Answer 15

Cement lines - potential source of weakness - can can cause fracture or crack

Question 16

What are the characteristics of Cancellous bone?

Answer 16

High turnover
Lower Young’s modulus

Question 17

Describe the structure of cancellous bone

Answer 17

Composed of trabecular - lamellae arranged as struts or plates in a loose open network which is highly porous with the pores being filled by red marrow

Question 18

What is the broad microscopic subdivision of bone

Answer 18

Cells (10%)
Extracellular matrix (90%)

Question 19

What are the four main types of bone cells

Answer 19

1. Osteoblasts
2. Osteoclasts
3. Osteocytes
4. Bone lining cells

Question 20

Where do osteoblasts originate from? What are some other cell types that differentiate from this lineage

Answer 20

Mesenchymal stem cell lineage.
Fibroblasts, chondroblasts, myoblasts, lipoblasts

Question 21

What do osteoblasts produce

Answer 21

Unmineralised bone matrix - osteoid which eventually becomes mineralised by calcium and becomes hard

Question 22

What lineage do osteoclasts come from and what other cell type also descend from this lineage?

Answer 22

Haemopoetic

Question 23

Draw a diagram of an osteoclast absorbing bone and label all the relevant parts

Answer 23

Refer to Video 1 of let’s talk Dr basic science

Question 24

What does the acid produced by osteoclasts break down

Answer 24

Inorganic bone - calcium hydroxyapatite

Question 25

What factor produced by osteoclasts breaks down organic (type 1 collagen) component of bone?

Answer 25

TRAP - Tartrate resistant acid phosphatase

Question 26

Define an osteocyte

Answer 26

Mature osteoblast covered in osteoid

Question 27

What do osteocytes do?

Answer 27

Detect chemical changes to lay down new bone and recruit bone lining cells

Question 28

Subdivide the extracellular matrix (90%) of bone

Answer 28

Organic (40%)/Inorganic (60%)

Question 29

What makes of the organic part of the extracellular matrix?

Answer 29

Type 1 collagen Glycoproteins Growth factors

Question 30

What is type 1 collagen responsible for?

Answer 30

Tensile strength of bone

Question 31

What is the main component of inorganic extracellular matrix?

Answer 31

Calcium hydroxyapatite which provides the compressive strength

Question 32

What is the formula for calcium hydroxyapatite

Answer 32

Ca₁₀(PO₄)₆(OH)₂

Question 33

What percentage of cardiac output does bone have and how would you classify this?

Answer 33

5-10% Anatomy and physiology

Question 34

What are the three main blood supplies of bone?

Answer 34

1. Nutrient artery system - high pressure 2. Metaphyseal-epiphyseal system 3. Periosteal system - low pressure

Question 35

How does the nutrient artery work

Answer 35

Branch from major artery - enters the bone at mid diaphysis from nutrient foramen

Question 36

How does normal blood flow work physiologically?

Answer 36

Centrifugally - inside to out from high to low pressure

Question 37

How does blood flow work in developing bone or fracture

Answer 37

Centripetal - high - low (out to in) as periosteum is thicker