Bones

Question 1

Name the 5 classifications of bones.

Answer 1

Long bone
Flat bone
Short bone
Irregular bone Sesamoid bone

Question 2

What is the axial skeleton?

Answer 2

Bones of head and trunk

Question 3

What is the appendicular skeleton?

Answer 3

Supports the appendages (all the other bones)

Question 4

Describe long bones. And give an example.

Answer 4

Tubular shape with hollow shaft, and ends expanded for articulation with other bones

Cancellous & compact bone

Appendicular skeleton, femur, humerus, ulna

Question 5

Describe short bones. And give an example.

Answer 5

Cuboidal/round shape

Cancellous surrounded by compact bone

Carpals & tarsals

Question 6

Describe flat bone.

And give an example.

Answer 6

Plates of bone, often curved

Thin inner & outer layer of compact bone

Protection - skull, ribs

Question 7

Describe irregular bone.

And give an example.

Answer 7

Fits into no other categories

Various shapes, vertebrae, sphenoid

Question 8

Describe Sesamoid bone. And give an example.

Answer 8

Small bones inside tendons

Reduce friction on tendon

Patella

Question 9

What is the difference between primary and secondary bone?

Answer 9

Primary - bone tissue that appears in embryological development (immature)

Secondary is what replaces primary bone in maturity

Question 10

What are the three categories of bone structure?

Answer 10

Bone matrix
Woven bone
Lamellar bone

Question 11

What are the components of bone matrix?

Answer 11

20% OSTEOID
(organic component)
-type I collagen
-GAGs

70% MINERAL
(inorganic component)
-calcium & phosphate forming hydroxyapatite

10% WATER

Question 12

What are the components of woven bone?

Answer 12

Coarse collagen fibres with low mineral content

Question 13

Where is woven bone found in the body?

Answer 13

Produced rapidly for fracture repair and in embryological development

Gets remodelled

Question 14

What is the basic structure of lamellar bone?

Answer 14

Regular, parallel collagen fibres

Question 15

What are the two types of lamellar bone?

Answer 15

Compact/cortical: outer shell of long bones, very dense

Cancellous/spongy: less dense, weaker & more flexible

Question 16

What are GAGs?

Answer 16

Glycosaminoglycans

Carbohydrate polymers attached to extracellular matrix proteins to form proteoglycans

Question 17

What is hydroxyapatite?

Answer 17

The mineral component of bone

Mainly calcium and phosphate

Question 18

What is ossification?

Answer 18

The process of laying down new bone material by cells called osteoblasts.
Bone tissue formation.

Question 19

Two types of ossification?

Answer 19

Intramembranous

Endochondral

Question 20

What type of bone is made by intramembranous ossification?

Answer 20

Flat bones - skull, clavicle

Some cortical/compact bone

Question 21

How does intramembranous ossification work?

Answer 21

Bones form within sheets of connective tissue

Mesenchymal stem cells replicate and form an ossification centre (clump of cells)

The cells differentiate into osteoprogenitor cells, then into osteoblasts

Osteoblasts secrete osteoid, which is then mineralised

So you have bone! Which is then remodelled by osteoclasts & blasts to make flat sheets

Question 22

What type of bone is made by Endochondral ossification?

Answer 22

Most other (non-flat) bones

Question 23

How does Endochondral ossification work?

Answer 23

Replacement of pre-devloped cartilage to form bone

Embryonic Mesenchymal cells condense forming the hyaline cartilage model

Blood vessels penetrate bringing nutrients & osteoprogenitor cells

Osteoprogenitor cells differentiate into osteoblasts, creating a primary ossification centre

Osteoblasts deposit bone matrix, building cancellous bone in shaft and cortical bone at collars

Bone is remodelled

Question 24

What are the functions of bone?

Answer 24

Support - framework for attachment of muscles & other tissues

Protection - protect internal organs

Movement - act as levers and points of attachment for muscles