Bone

Question 1

What type of tissue is bone?

Answer 1

Connective tissue.

Question 2

What are the functions of bone?

Answer 2

Weight-bearing and support for mechanical function
Protection
Mineral store
Blood formation (red bone marrow)

Question 3

Name some types of bone.

Answer 3

Flat, long, sutural, short, irregular, sesamoid.

Question 4

What is cortical bone?

Answer 4

Compact/hard bone.

Question 5

What is trabecular bone?

Answer 5

Spongey bone.

Question 6

Why is bone highly vascularised?

Answer 6

There are many blood vessels.

Question 7

What is stored in the medullary cavity?

Answer 7

Red bone marrow- produces blood cells.

Question 8

What are the membranes?

Answer 8

Periosteum (membrane surrounding bone)

Endosteum (inside the membrane)

Question 9

How is cortical bone arranged?

Answer 9

Arranged in Osteons/Havernious systems- small circular structures with perforating canals around.

Question 10

What lies around Haversion canals?

Answer 10

Osteocytes and bone matrix lamellae.

Question 11

How is trabecular bone arranged?

Answer 11

Less dense than cortical bone, no Osteons/Havernious canal systems- have a network of lamellated trabecular which are filled with bone marrow. The orientation of trabeculae reflects the main direction of mechanical force.

Question 12

What are the two types of bone formation?

Answer 12

Endochondral

Intramembraneous

Question 13

What is the most common type of bone formation?

Answer 13

Endochondral.

Question 14

What happens during endochondrial ossification?

Answer 14

The bone forms firstly as a cartilage model.
Blood vessels then invade the cartilage.
The cartilage is replaced with bone- it remains in an epiphyseal growth phase then eventually ossifies.

Question 15

What distinguishes endochondrial ossification?

Answer 15

Cartiligonous phase.

Question 16

What happens during intermembranous ossification?

Answer 16

Mesenchymal cells develop into osteoprogenitor cells which mature into osteoblasts and start depositing bone.
Residual mesenchymal cells deposit blood and bone marrow.
This bone formation also occurs in adult cortical bone.

Question 17

What is bone composed of?

Answer 17

Cells (osteoblasts/osteocytes/osteoclasts)
Extracellular matrix
Minerals
Collagen

Question 18

What are the 3 types of cell in the bone?

Answer 18

Osteoblasts
Osteocytes
Osteoclasts

Question 19

What is the bone extracellular matrix composed of?

Answer 19

45% hydroxyapatite crystals (complex form of calcium phosphate), water, collagen.

Question 20

What do minerals do in the bone?

Answer 20

Stiffen / rigidify structures.

Question 21

What does collagen do?

Answer 21

Gives support and flexibility- reduces the risk of fracture because it has a high threshold of tension.

Question 22

What does healthy bone have a balance of?

Answer 22

Bone remodelling- removal/formation.

Question 23

Is bone remodelling a constant process?

Answer 23

Yes- even in adult bone.

Question 24

What do osteoclasts do?

Answer 24

Reabsorb bone matrix.

Question 25

Where are osteoclasts found?

Answer 25

Surface of bone mineral.

Question 26

What do osteoblasts do?

Answer 26

Role in initial bone formation and bone remodelling.

Question 27

Where are osteoblasts found?

Answer 27

Periosteum / endosteum

Question 28

What do osteocytes do?

Answer 28

Maintain the mineral concentration through enzyme secretion.

Question 29

Where are osteocytes found?

Answer 29

Lacunae.

Question 30

Name some disorders of bone remodelling.

Answer 30

Osteoporosis, osteopetrosis, Paget’s disease.

Question 31

What is bone mass controlled by?

Answer 31

Genetics and environment.

Question 32

What else can affect bone mass/

Answer 32

High mechanical load (eg. athletes).