Bone

Question 1

What is contained in the EC matrix of bone?

Answer 1

• Type I Collagen
• Ground substance
• Minerals

Question 2

What are the two types of bone formation?

Answer 2

Endochondral: The Formation of bone in which a cartilage template is gradually replaced by a bone matrix

Intramembranous: Development of bone from tissue or membrane.

Question 3

What are the zones of endochondral bone growth from the middle to the end if the long bone?

Answer 3

Resting —> Proliferating —> Hypertrophic —> Calcification —> Reabsorption —> Bone Deposition

Question 4

Which types of bones form from which type of growth?

Answer 4

Endochondral: Compact Bone (Long)

Intramembranous: Spongy Bone (Short, flat, irregular)

Question 5

Describe the process of intramembranous ossification?

Answer 5

1. Mesenchymal cell condense and differentiate into osteoblasts to form primary ossification center
2. Osteoblasts Secrete Osteoid to form primary woven bone matrix; Become trapped in lacunae and become osteocytes
3. Osteoblasts fill in spaces in spongy bone producing osteoblasts with their trapped blood vessels
4. Bone is remodels through balance of osteoblasts/clasts

Question 6

What are the types of bone cells and their roles?

Answer 6

Osteoprogenitor cells - stem cells

Osteoblasts - Produce Primary matrix

Osteocytes - Trapped in lacunae

Osteoblasts - Bone reabsorption

Question 7

What are the layers of the periosteum?

Answer 7

1. Outer fibrous layer

2. Deep inner osteopenia layer

Question 8

How does cancellous bone differentiate structurally from compact?

Answer 8

• No haversion canals

- irregular shapes and marrow spaces

Question 9

How are Bone cells differentiated by stain?

Answer 9

Osteoblasts are basophilic

Osteoblasts are acidophilic

Question 10

What are sharper fibers?

Answer 10

Fibrous CT which anchor the periosteum

Question 11

What hormones affect bone?

Answer 11

Calcitonin - Inhibits bone reabsorption

Parathyroid - Increases osteoclasts activity

Question 12

What results from VD deficiency?

Answer 12

• Poor mineralization of bone matrix
• Do not harden sufficiently
• Rickets/Osteomalacia

Question 13

What are the main hereditary bone disorders?

Answer 13

Achondroplasia - chondrocytes division inhibited; Endochondrol bones affected. Most common dwarfism

Osteogenesis imperfecta- Brittle Bone Disease; Type I collagen defects.

Question 14

What are the hormonal bone diseases?

Answer 14

Acromegaly - Exces GH in adults; inverses formation producing thicker periosteum and coarsened facial features

Gigantism - Excess GH in children leading to extended growth.

Pituitary dwarfism - Decreases GH reduces both endochondral and membranous ossification.