Bone - 2017

Question 1

Bone is ___% inorganic hydroxyappetite and _______% organic with ___% collagen and ____% non collagenous protein

Answer 1

67
33
28
5

Question 2

What are the 4 main physiological role of bone?

Answer 2

1-Structural
2-Calcium homeostasis (9-10 mg/dL)
3-Reservoir for growth factors in tissue repair
4-Contains both hematopoietic and mesenchymal progenitor cells in bone marrow

Question 3

What links haversian canals to link osteons?

Answer 3

volkmann canals

Question 4

Calcitonin ____ blood Ca++ while parathyroid _____ blood Ca++

Answer 4

lowers, raises

Question 5

What are the 3 units of compact bone?

Answer 5

1-Circumferential (outer ring of bone)
2-Concentric lamellae (intact osteons)
3-Interstitial lamellae (former concentric lamellae filling in between)

Question 6

Concentric lamella form around haversian canals forming a cylindrical structure called what?

Answer 6

Osteon

*basic functional unit of compact bone

Question 7

Found at the ends of long bones, what type of bone provides structure in marrow spaces?

Answer 7

Cancellous bone (spongy/trabecular)

Question 8

The connective tissue layer attached to the outer surface of a bone by sharpeys fibers is called? What are the two layers of the periosteum?

Answer 8

Periosteum

*has two layers, outer fibrous and inner highly cellular/vascularized

Question 9

Loose connective tissue covering the inner surface of both cancellous and compact bone whose purpose is to separate the marrow from the bone is called?

Answer 9

Endosteum

Question 10

Which bone cells are of mesenchymal origin?

Answer 10

Osteoblasts and Osteocytes (trapped osteoblasts)

Question 11

Which bone cell is of hematopoietic origin?

Answer 11

Osteoclast

Question 12

Which bone cells are mono nucleated, synthesize osteoid, arise from mesenchyme in response to a cascade of growth factors, and communicate with one another through gap junctions?

Answer 12

Osteoblasts

*secrete growth factors into osteoid matrix

Question 13

Which bone cells are large, multi-nucleated cells responsible for resorption and are marked by Tartrate Resistant acid phosphatase?

Answer 13

Osteoclasts

Question 14

What activates Osteoclast differentiation?

Answer 14

IL-1B and TNF-a

Question 15

What do osteoclasts form in order to secrete hydrogen ions and matrix degrading enzymes and transcytose broken down products? What protein that form the seal around this structure? What is the zone between this structure and intact bone called?

Answer 15

Howships Lacunae make by the ruffled border

integrin

*lamina limitans is the zone between the howships lacunae and intact bone

Question 16

What system is used to regulate osteoblast and osteoclast function?

Answer 16

RANK-RANKL-OPG system

Question 17

Which cells express RANKL?

Answer 17

Osteoblasts

Question 18

Which cells express RANK?

Answer 18

Osteoclasts

Question 19

What ligand is produced by osteoblasts to bind RANKL as a competitive antagonist to RANK?

Answer 19

OPG (Osteoprotegerin)

Question 20

What bone formation process starts with a hyaline cartilage pattern followed by mesenchymal cells condensing into chondrocytes into which collagen is secreted, mineralized and penetrated by vasculature?

Answer 20

Endochondral formation (typically long bones)

*Vasculature brings osteoblasts which start forming bone matrix

Question 21

What structure make up the primary spongiosa and are bone matrix surrounding mineralized cartilage?

Answer 21

Mixed Spicules

Question 22

Where are the secondary growth centers of some long bones?

Answer 22

Growth plates or epiphyses

Question 23

What bone formation process is mesenchymal cells condensing in fibrous CT, differentiating into osteoblasts and forming an ossification center?

Answer 23

Intramembranous formation

Question 24

Woven bone is _____formed and is then remodeled into mature ______ bone with a collar of _______ bone around it

Answer 24

Rapidly, trabecular, cortical

Question 25

What are fibrous connective tissue bands between plates of bone called? What are the two layers of these bands that join to close them? What is the purpose of this kind of joint?

Answer 25

Sutures

*inner cambian layer associated with periosteum, outer layer meets to join sutures

the purpose is to give flex to the skull as bone formation proceeds

Question 26

Bone is mainly formed around the _______ and resorbed from the ________ allowing the marrow cavity to grow

Answer 26

Periosteum, endosteum

Question 27

What are the two shapes of cortical cone osteon formation?

Answer 27

Cutting cone (osteoclasts)
Filling cone (osteoblasts)

Question 28

How do osteoblasts secrete collagen?

Answer 28

via vesicles

Question 29

What cells are entrapped in bone and possibly have cellular process which interact with surrounding bone tissue to coordinate osteoblast/clast activity?

Answer 29

osteocytes

Question 30

How do osteoclasts in Howship’s lacunae move the resorbed bone components?

Answer 30

transcytosis