Chapter 6

Question 1

What are 6 main roles of bone

Answer 1

Support, movement, protection for organs, mineral homeostasis, hemopoiesis, triglyceride storage

Question 2

Define disphysis

Answer 2

Bone shaft

Question 3

Define epiohyses

Answer 3

Growth plates at ends of bone

Question 4

Metaphases

Answer 4

Region between diaphysis ans epiphyses, contains epiphyseal plate

Question 5

What is articular cartilage

Answer 5

Hyaline cartilage covering epiphyses at joints, reduces shock and friction. Avascular, no perichondrium

Question 6

What is periosteum?

Answer 6

Connective tissue sheath covering bone. Contains blood vessels. Has outer fibrous layer and inner osteogenic layer. Protects bone, assists in repair, provides attachment for ligaments

Question 7

What are perforating fibres?

Answer 7

Attaches periosteum to bone

Question 8

What are osteoprogenitor cells?

Answer 8

Originate from mesenchyme, unspecialized bone stem cells, only ones that divide. Found in periosteum, endosteum, and central canals

Question 9

How do blood vessels penetrate bone?

Answer 9

Through transverse interosteonic canals

Question 10

How do osteocytes communicate?

Answer 10

Gap junctions

Question 11

Where is spongy bone tissue found?

Answer 11

In epiphyses, rim of medullary cavity, short, flat, sesamoid and irregular bones

Question 12

Where is red bone marrow found?

Answer 12

Hip bones, ribs, sternum, vertebrae, proximal ends of humerus and femur

Question 13

What are the blood supplies for bone

Answer 13

Outer part of bone and periosteum–periosteal arteries
Inner part of bone, spongy bone, and marrow–nutrient artery
End of long bones–epiphyseal and metaphyseal arteries

Question 14

What are the two types of osteogenesis?

Answer 14

Intramembranous and endochondral

Question 15

What are the steps for intramembranous ossification?

Answer 15

1. Development of ossification centre
2. Calcification
3. Formation of trabeculae
4. Development of periosteum

Question 16

What are the steps of endochondral ossification

Answer 16

1. Development of cartilage model
2. Growth of cartilage model
3. Development of primary ossification center (proceeds inward)
4. Development of medullary cavity
5. Development of secondary ossification center
6. Formation of articular cartilage and epiphyseal plate

Question 17

What bones are grown from each method of ossification?

Answer 17

Endochondral–most bones, long bones
Intramembranous–flat bones of skull, most facial bones, mandible and clavicle

Question 18

What cells form medullary cavity?

Answer 18

Osteoclasts

Question 19

What is interstitial and appositional growth?

Answer 19

Interstitial–length
Appositional–width

Question 20

Primary vs secondary ossification center

Answer 20

Primary in diaphysis, secondary in epiphysis

Question 21

How does growth occur at epiphyseal plates?

Answer 21

Growth occurs from zone of proliferating cartilage, secretes ECM. The proliferating cartilage creates more chondrocytes which develop in the zone of hypertrophic cartilage. The ECM calcifies, and chondrocytes die, and endochondral ossification occurs.

Question 22

How is the epiphyseal plate anchored to bone?

Answer 22

At the zone of resting cartilage, through chondrocytes

Question 23

How does appositional growth occur?

Answer 23

1. Periosteal cells differentiate into osteoblasts, secrete ECM, forms ridges
2. Ridges fold and fuse to form tunnels, enclosing blood vessels
3. Endosteum osteoblasts form concentric lamellae to form osteon
4. As osteon forms, osteoblasts deposit new circumferential lamellae

Question 24

What are the parts to the feedback cycle for calcium?

Answer 24

Receptors: parathyroid gland cells
Input: cAMP
Control center: PTH gene
Output: PTH
Effectors: osteoclasts and kidneys

Question 25

What is calcitonin?

Answer 25

Secreted from parafollicular cells in thyroid, inhibits osteoclasts

Question 26

What factors affect bone growth and remodelling?

Answer 26

Minerals, hormones (insulin like growth factor, stimulates osteoblasts, T3 and T4 stimulate osteoblasts, insulin helps synthesize proteins, estrogen and other sex hormones), vitamins (A, C, D, K, B12)