Week 11: Bone Tissue, Growth and Healing

Question 1

What are the components of bone tissue?

Answer 1

supporting connective tissue, specialized cells, inorganic components (calcium salt deposits) and organic components (collagen fibres)

Question 2

What is the bone matrix made up of?

Answer 2

70% hydroxyapatite (inorganic) and 30% collagen fibres (organic)

Question 3

What are the 4 types of bone cells?

Answer 3

osteoprogenitor cells, osteoblasts, osteocytes, osteoclasts

Question 4

What are osteoprogenitor cells?

Answer 4

stem cells that divide to produce osteoblasts

Question 5

Where are osteoprogenitor cells located?

Answer 5

in the endosteum and the inner cellular layer of periosteum

Question 6

What is the main function of osteoprogenitor cells?

Answer 6

assist in fracture repair

Question 7

What are osteoblasts?

Answer 7

immature bone cells that secrete matrix compounds

Question 8

What are osteocytes?

Answer 8

mature bone cells that maintain the bone matrix

Question 9

Where are osteocytes located?

Answer 9

in lacunae and between layers of matrix

Question 10

What are the functions of osteocytes?

Answer 10

maintain protein and mineral content of matrix, to help repair damaged bone

Question 11

What are osteoclasts?

Answer 11

derived from stem cells in bone marrow that produce macrophages

Question 12

What is the function of osteoclasts?

Answer 12

dissolve bone matrix and release stored minerals

Question 13

What has to be balanced to achieve bone homeostasis?

Answer 13

bone building by osteoblasts and bone breakdown by osteoclasts

Question 14

What are the features of a compact bone?

Answer 14

osteon (basic transport unit), osteocytes arranged in concentric lamellae around a central canal, perforating canals (perpendicular to central canal), circumferential lamellae (bind osteons together)

Question 15

What are the features of a spongy (cancellous) bone?

Answer 15

no osteons, open network of trabeculae (spaces between are filled with red and yellow bone marrow)

Question 16

Where can periosteum be found?

Answer 16

covering compact bone (excluding parts in joint capsules)

Question 17

What is the function of periosteum?

Answer 17

isolate bone from surrounding tissue, provide a route for blood and nerve supply, participate in bone growth and repair

Question 18

What are the two layers of the periosteum?

Answer 18

fibrous layer and cellular layer

Question 19

Where can endosteum be found?

Answer 19

on the inside of compact bone

Question 20

Define osteogenesis

Answer 20

bone formation

Question 21

what is ossification?

Answer 21

the process of replacing other tissues with bone

Question 22

What are the forms of ossification?

Answer 22

endochondral ossification and intramembranous ossification

Question 23

What is endochondral ossification?

Answer 23

ossifies bones that originate as hyaline cartilage

Question 24

What is intramembranous ossification?

Answer 24

produces flat bones

Question 25

How is blood supplied to mature bones?

Answer 25

nutrient artery and vein, metaphyseal vessels (supplies epiphyseal cartilage), periosteal vessels (supplies superficial lamellae)

Question 26

How is a fracture repaired?

Answer 26

1- bleeding, producing a clot
2- cells of endosteum and periosteum move into fracture zone
3- osteoblasts form spongy bone
4- osteoblasts, osteocytes and osteoclasts remodel he fracture or up to a year