MS System - Bones

Question 1

Describe the functional anatomy of a long bone

Answer 1

Epiphysis - Top/End of the bone - mainly made of trabecular bone
Metaphysis - connects the epiphysis and diaphysis at the neck of the bone, region of growth during
development
Diaphysis - Shaft of the bone, mainly made of cortical bone

Bone marrow is contained in the diaphysis

Periosteum - fibrous connective tissue sheath covering cortical bone

Question 2

Name some types of long bone

Answer 2

Humerus, Tibia, Femur, Fibula, Ulna, Radius, Metacarpals and Phalanges

Question 3

What is the structure of cancellous bone ?

Answer 3

Spongy trabecular bone
Give supporting strength to weight bearing ends of bone
The trabeculae are laid down along lines of stress
The gaps in the trabecular bone contain, osteocytes, osteoclasts, osteoblasts, lacuna etc.

Question 4

What is the structure of compact bone ?

Answer 4

Cortical, strong bone
On the outside of the bone, forms the shaft of long bones
Provides stiffness and strength

Question 5

Haematopoiesis

Answer 5

Blood cell formation in bone marrow

Question 6

What is cartilage ?

Answer 6

Strong connective tissue that supports the body and is softer and more flexible than bone (NOT CALCIFIED)

Question 7

What is bone ?

Answer 7

Flexible cartilage hardened by minerals

Question 8

What would happen to bones without

1. Collagen ?
2. Minerals ?

Answer 8

1. Shatter
2. Become bendy

Question 9

Epiphysis

Answer 9

Flared end of the long bone
Articular Surface
Covered in hyaline cartilage

Question 10

Diaphysis

Answer 10

Shaft of the long bone
Hollow cylinder
Contains bone marrow
Porous

Question 11

Nutrient Foramen

Answer 11

Small opening in the middle of the external surface of the diaphysis, through which an artery enters the bone to provide nourishment (via blood supply)

Question 12

Periosteum

Answer 12

Fibrous connective tissue sheath, covering external bone surfaces that supplies blood, nerves and cells

Question 13

What 3 cell types are present in the periosteum ?

Answer 13

1. Fibroblasts
2. Mesenchymal cells
3. Osteoclasts

Question 14

Fibroblasts

Answer 14

Cells that synthesise collagen

Question 15

Mesenchymal cells

Answer 15

Able to differentiate into osteoblasts and chondroblasts

Question 16

Metaphysis

Answer 16

Growth zone between the epiphysis and diaphysis during growth in childhood.

Question 17

What are the 2 major types of bone ?

Answer 17

1. Trabecullar
2. Cortical

Question 18

Are all bone cells in contact with blood vessels ?

Answer 18

No, for example osteocytes

Question 19

In what formation do cortical bones arrange themselves ?

Answer 19

Concentric circles

Question 20

Haversian canals

Answer 20

Carry blood vertically

Question 21

Volkman’s canals

Answer 21

Carry blood perpendicularly through bone.

Question 22

What is the anatomical unit of cortical bone ?

Answer 22

Osteon

Question 23

What type of fibres are located inside of cortical bone ?

Answer 23

Collagen

Question 24

What characteristic do network fibres provide to cortical bone ?

Answer 24

Flexibility and strength

Question 25

Which compound adds strength and hardens cortical bone ?

Answer 25

Calcium hydroxyapatite

Question 26

What is the anatomical unit of trabecular bone ?

Answer 26

Trabecula

Question 27

How is collagen arranged in the bone matrix ?

Answer 27

Highly organised in parallel arrangement.

Question 28

Vitamin D function

Answer 28

Regulates the amount of calcium and phosphate in the body

Question 29

Rickets

Answer 29

Vit D deficiency

Question 30

Vitamin C function

Answer 30

A nutrient the body needs for blood vessels, cartilage, muscle and collagen.

Question 31

Scurvy

Answer 31

Vit C deficiency

Question 32

Osteoblasts

Answer 32

Bone forming cells - Single nucleus - Covers the surface of the bone - Forms an osseous matrix and becomes enclosed as an osteocyte

Question 33

Osteoclasts

Answer 33

Chew bone matrix by demineralisation - Multinucleated cells derived from haematopoietic cells - Respond to mechanical stress and physiological demands

Question 34

Osteocytes

Answer 34

Mature bone cells - Relatively inactive - Maintains bone matrix via cell-cell communication

Question 35

Osteoprogenitor cells

Answer 35

Bone stem cells

Question 36

Life cycle of osteoblasts

Answer 36

Derived from osteoprogenitor cells Stimulated to form bone at specific sites Deposition of organic matrix (collagen) then hydroxyapatite Eventually become entombed in mineral to form osteocytes

Question 37

What 2 things regulate osteoclasts ?

Answer 37

Hormones Osteoblasts

Question 38

What is the function of osteoclasts releasing H+ and hydrolytic enzymes ?

Answer 38

Dissolve minerals Liberate calcium Break down the extracellular matrix

Question 39

Where are osteocytes found ?

Answer 39

Embedded in the bone matrix (lacunae)

Question 40

Lacunae

Answer 40

small cavities in the bone that contain osteocytes

Question 41

How do osteocytes communicate ?

Answer 41

Finger like projections in canaliculi GAP junctions

Question 42

How is the equilibrium between osteoblast and osteoclast activity controlled ?

Answer 42

Signalling between different cells in bone Hormone signalling

Question 43

Calcitonin

Answer 43

Lowers activity of osteoclasts and blood calcium levels

Question 44

Parathyroid hormone

Answer 44

Increases activity of osteoclasts and blood calcium levels

Question 45

4 stages of TRABECULAR bone remodelling

Answer 45

1. Quiescence 2. Resorption by osteoclasts (burrowing into bone structure) 3. Osteoprogenator cells triggered (differentiate into osteoblasts) 4. Osteoblasts lay down new bone

Question 46

3 stages of CORTICAL bone remodelling

Answer 46

1. Osteoclasts reabsorb bone 2. Osteoblasts lay down a new matrix 3. Osteoblasts become embedded and become osteocytes

Question 47

Wolf's Law

Answer 47

Bone ADAPTS to the load under which it is placed "Use it or Lose it"

Question 48

Causes of bone mass and density increase (1)

Answer 48

Excessive mechanical simulation

Question 49

Causes of bone mass density decrease (3)

Answer 49

Non weight bearing (Immobilisation) Sex hormone deficiency (Menopause) Endocrine and nutritional disorders

Question 50

Osteoporosis

Answer 50

A pathological condition where chewing outweighs the building

Question 51

Where does bone growth begin during fetal life ?

Answer 51

Diaphysis

Question 52

Name the 5 zones in bone lengthening

Answer 52

Resting zone - chondroblasts Growth zone - mitosis of chondroblasts, forming columns Hypertrophic zone - chondroblasts become chondrocytes Calcification zone - chondrocytes deposit minerals between the columns. This destroys the chondrocytes. Ossification zone - columns break down, osteoblasts lay down new disorganised bone which is eventually remodelled by osteoclasts and blasts.