Bone

Question 1

What is endchrondrial ossification?

Answer 1

Formation of bone from cartilage

Question 2

What is intramembranous ossification?

Answer 2

Bone from forming from mesenchymal tissue (MSC)
Cells that can differentiate into different cells
make flat bones e.g. Skull, clavicle

Question 3

How do mesenchymal cells form into compact bone?

Answer 3

MSCs
Osteoprogenitor cells
Osteoblasts (osteoblasts)
Mineralises (osteoclasts and osteocytes)
Mature compact bone

Question 4

What are a) osteoblasts b)osteoclasts and c)osteocytes?

Answer 4

A)Lie on edge of bone and lay down new bone.
B)Absorbs bone tissue during healing using H+ ions and lysosomal enzymes - remodel bone
C)Mature bone cell - has close gap junctions to pass nutrients between cells.

Question 5

What is cancellous vs compact bone?

Answer 5

Cancellous = spongy
Compact = hard - 80% of bone

Question 6

What are Haversian and Vockman canals?

Answer 6

Canals that carry blood vessels, lymph vessel and nerves between bone.

Question 7

What is the structural difference between mature and immature bone?

Answer 7

Mature bone - spirals of osteons

Immature - randomly arranged osteons

Question 8

What does bone contain?

Answer 8

Calcium minerals (65%)
Type 1 collagen (23%)
Water (10%)
Non-collagen proteins (2%)

Question 9

What two properties help bone withstand fracture?

Answer 9

Great compressive and tensile strength

Flexibility

Question 10

What a bone first fractures, what is the first stage of repair?

Answer 10

Hematoma formation
Bone cells die and osteoclasts remove dead tissue
Inflammation and swelling
Phagocytic cells gather

Question 11

After a hematoma has formed, what is the second stage of bone repair?

Answer 11

Fibrocartilagenous callus formation 
Proclaims of granulation tissue forms (capillaries)
Fibroblasts lay down collagen
Osteoblasts begin laying down new bone 
Hyaline cartilage formation

Question 12

After fibrocartilaginous callus formation, what is the third stage of bone repair?

Answer 12

Bony callus formation
Endochrondrial ossification replaces cartilage
Intramembranous ossification forms new bone
Last between 2 days - 2 months

Question 13

After bony callus formation, what is the last stage of bone repair?

Answer 13

Bone remodelling
Cancellous bone is remodelled into compact bone
Remodelling by osteoclasts

Question 14

When using bone banks in surgery, what is an autograft, an homograft, and a heterograft?

Answer 14

Autograft - patient’s own bone
Homograft - another human’s bone
Hetreograft - animal’s bone e.g. calf

Question 15

What is osteoporosis?

Answer 15

A disease where mineralised bone decreases in mass

Bone no longer provides adequate support to is susceptible to fracture.

Question 16

How do normal via osteoporosis bone look different?

Answer 16

Normal - solid bone

Osteoporosis - lots of little holes in bone

Question 17

What is type 1 osteoporosis?

Answer 17

Post menopausal women

Increase in osteoclast number due to reduction in oestrogen

Question 18

What is Type 2 osteoporosis?

Answer 18

‘Senile’ osteoporosis
Happens in both sexes
Age age - reduction in osteoblast function

Question 19

What five factors affect osteoporosis?

Answer 19

Genetics - less common in black people
Calcium deficiency
Vitamin D deficiency - old people stay indoors
Exercise - lack of leads to bone loss
Smoking - correlation in women