MS System: Bones

Question 1

What are the basic functions of bone?

Answer 1

Enables movement

Protection of vital organs

Storage of minerals

Haematopoiesis- blood cell formation

Question 2

What two elements are bone made up?

Answer 2

Collagen fibres- mucopolysaccharide

Calcium phosphate- hydroxyapatite

Question 3

What does collagen fibre framework give the bone?

Answer 3

Its tensile strength

Question 4

What does calcium phosphate give the bone?

Answer 4

Compressional strength

Question 5

What are the three basic cells of bone?

Answer 5

Osteoblasts

Osteocytes

Osteoclasts

Question 6

What are the different structures of the long bone?

Answer 6

Epiphysis- head

Diaphysis- shaft

Periosteum- fibrous connective sheath

Metaphysis- between epiphysis and diaphysis

Question 7

What does fibroblasts produce?

Answer 7

Collagen

Question 8

What are mesenchymal cells?

Answer 8

Cells that can differentiate into osteoblasts and chondroblasts

Question 9

What is the epiphyseal line?

Answer 9

Area of growth of long bone

Question 10

When looking at a cross section of a bone, what are then different layers?

Answer 10

Periosteum

Shaft compact bone

Medullary cavity

Question 11

What are the two types of bone in long bones?

Answer 11

Trabecular/cancellous

Cortical

Question 12

Describe trabecular bone

Answer 12

Spongy and porous

Give supporting strength to the ends of the weight bearing bone

Have high surface area for metabolism

Question 13

Describe cortical bone

Answer 13

Bone on the outside that forms the shaft of the long bone

Provides stiffness and strength

Question 14

How is trabeculae bone laid down?

Answer 14

They are laid down along lines of stress

This allows for distribution of stress

Question 15

What are the two different canals blood is carried to the bone?

Answer 15

Volkman’s and Haversian canals

Question 16

In what direction does Haversian and Volkman’s canals carry blood?

Answer 16

Haversian- along long axis

Volkman’s- Perpendicularly

Question 17

What is rickets?

Answer 17

Vitamin D deficiency- failure of calcium absorption

Question 18

What is scurvy?

Answer 18

Vitamin C deficiency- lack of collagen

Question 19

What are osteoblasts?

Answer 19

Mononucleate cells

When stimulated to form bone will deposit organic matrix then hydroxyapatite

Question 20

What are osteoclasts?

Answer 20

Multinucleate

Release hydrogen and hydrolytic enzymes to dissolve the mineral, liberate calcium and breakdown extracellular matric

Question 21

What are osteocytes?

Answer 21

Ebtomed and matured osteoblasts

Communicate via finger-like projections in canaliculi

Question 22

What is the function of calcitonin?

Answer 22

Decrease activity of osteoclasts and blood calcium levels

Question 23

What is the function of parathyroid hormone?

Answer 23

Increase activity of osteoclasts

Releases calcium

Question 24

What are the different steps of trabecular bone remodelling?

Answer 24

Quiescence

Resorption by osteoclasts

Surface exposed to osteoprogenitors, osteoblasts start to differentiate

Osteoblasts lay down new bone

Question 25

What are the different steps I cortical bone remodelling?

Answer 25

A cutting cone is formed through osteoclasts, this is followed by osteoblasts which eventually get surrounded and become osteocytes

Question 26

What is Wolff's law?

Answer 26

Bone adapts to the load under which it is placed

Question 27

How can bone mass and density increase?

Answer 27

Excessive mechanical stimulation

Question 28

How can bone mass and density decrease?

Answer 28

Non-weight bearing Sex-hormone deficiency Endocrine/nutritional disorders

Question 29

When does woman have a significant decrease in bone mass?

Answer 29

Menopause Caused by the decrease in oestrogens levels

Question 30

What is cartilage formed by?

Answer 30

Formed by chondroblasts Reshaped by chondrocytes

Question 31

Where does bone growth begin in fetal life?

Answer 31

Diaphysis

Question 32

What happens to cartilage in foetuses?

Answer 32

Ossification Endochondral- long bones Intramembranous- flat bones

Question 33

After birth where does bone growth occur?

Answer 33

In the epiphysis Secondary centre of ossification

Question 34

Describe how bone growth occurs after birth?

Answer 34

The epiphyseal plate is replaced with bone and at the end of puberty these fuse

Question 35

Describe bone repair in fractures?

Answer 35

Callus formation- osteoblasts quickly form woven bone to bridge the gap Lamellar bone laid down- collagen organised in regular sheets to gives strength and resilience Remodelling by osteoclasts to restore original bone shape