Exam 4 - Bone 1

Question 1

Functions of bone

Answer 1

• Support
• Protection: skull around brain; ribs, sternum, vertebrae, protect organs of thoracic cavity
• Movement
• Storage of Ca and P
• Blood cell production
• Enhances insulin effects

Question 2

Osteocalcin

Answer 2

Secreted from osteoblasts

• increases number of beta cells in pancreas
• increases sensitivity in tissues to insulin WHILE INHIBITING WEIGHT GAIN

Question 3

Dry weight of bone

Answer 3

1/3 organic

2/3 inorganic matter

Question 4

Organic matter of bone

Answer 4

collagen
glycosaminoglycans
proteoglycans
glycoproteins

Question 5

inorganic matter of bone

Answer 5

85% hydroxyapatite
10% calcium carbonate
other minerals (fluoride, potassium, magnesium)

Question 6

Combination of organic and inorganic materials of bone

Answer 6

Provides strength and resilience

• minerals resist COMPRESSION; collagen resist TENSION
• bone adapts by varying proportions

Question 7

If mineral is removed

Answer 7

bone is too bendable

Question 8

if collagen is removed

Answer 8

bone is too brittle

Question 9

osteogenic cells in endostium and periosteum…

Answer 9

give rise to NEW OSTEOBLASTS which arise from embryonic FIBROBLASTS

Question 10

produce and may help mineralize organic matter of matrix

Answer 10

Osteoblasts

Question 11

Osteoblasts trapped in the matrix they formed

Answer 11

OsteoCYTES

Question 12

Other information about osteocytes

Answer 12

• cells in lacunae connected by gap junctions inside canaliculi
• CONTRIBUTE TO HEMOSTATIC MAINTENANCE OF BONE DENSITY and blood concentrations of calcium and phosphates
• strain sensors: flow of extracellular fluid of lacunae and canaliculi results in remodeling if needed

Question 13

Spaces occupied by osteocyte cell body

Answer 13

Lacunae

Question 14

Canals occupied by osteocyte cell processes

Answer 14

Canaliculi

Question 15

Share no common origin w/ other bone cells

Answer 15

OsteoCLASTS

Question 16

basic structural unit of bone

Answer 16

osteon / Harvesian system

Question 17

run PARALLEL to long axis

Answer 17

Central / Harvesian canals

Question 18

Concentric layers of compact bone tissue that surround central canal

Answer 18

Lamellae

Question 19

Perforating / Volkmann’s canal

Answer 19

• runs PERPENDICULAR to long axis
• both perforating and central canals contain blood vessels
• DIRECT FLOW OF NUTRIENTS FROM VESSELS THROUGH CELL PROCESSES OF OSTEOBLASTS AND FROM ONE CELL TO THE NEXT

Question 20

Outer layer is fibrous

Answer 20

Periosteum

Question 21

Inner layer of periosteum

Answer 21

• consist of SINGLE LAYER OF CELLS including osteoblasts, osteoclasts, and osteochondral progenitor cells

Question 22

Fibers of tendons become continuous w/ fibers of …?

Answer 22

Periosteum

Question 23

Sharpey’s fibers

Answer 23

some periosteal fibers that penetrate through the periosteum and into the bone
- strengthen attachment of tendon to bone

Question 24

Endosteum

Answer 24

• similar to INNER LAYER OF PERIOSTEUM

- lines all lateral spaces including spaces in cancellous bone

Question 25

When you break a bone, what do you actually break?

Answer 25

Periosteum, the bone itself doesn't have innervation for you to feel

Question 26

How do osteoclasts develop?

Answer 26

by fusion of 3-10 stem cells - develop from bone marrow stem cells - osteogenic cells, osteoblasts, and osteocytes come from same cell lineage (MESENCHYME) BUT OSTEOCLASTS HAVE INDEPENDENT AND DIFFERENT ORIGIN

Question 27

Osteoclast responsibility

Answer 27

Resorption of bone - H+ ions pumped across membrane which eats away bone - Enzymes released that digest the bone

Question 28

Woven bone

Answer 28

- collagen fibers randomly oriented | - FORMED DURING FETAL DEVELOPMENT AND FRACTURE REPAIR

Question 29

Remodelling

Answer 29

- removing old bone and adding new | - woven bone is "remodeled" into lamellar bone

Question 30

Lamellar bone

Answer 30

- mature bone in sheets called LAMELLAE | - fibers are oriented in one direction in each layer, but in different directions in different layers for strength

Question 31

Spongy bone

Answer 31

Spongelike appearance formed by plates of bone called TRABECULAE - SPACES FILLED W/ RED BONE MARROW

Question 32

Have few osteons or central canals

Answer 32

Trabeculae; no osteocyte is far from blood of bone marrow

Question 33

Develop along bone's lines of stress

Answer 33

Trabeculae; provides strength w/ little weight

Question 34

Shaft comprised of COMPACT BONE

Answer 34

Diaphysis

Question 35

End of the bone comprised of CANCELLOUS BONE (SPONGY)

Answer 35

Epiphysis

Question 36

Comprised of hyaline cartilage; PRESENT UNTIL GROWTH STOPS

Answer 36

Epiphyseal plate

Question 37

In children _____ is filled w/ red bone marrow.

Answer 37

medullary cavity

Question 38

Endochondrial ossification takes place in...?

Answer 38

cartilage

Question 39

Intramembranous ossification takes place in...?

Answer 39

connective tissue "membrane" similar to the dermis | - as such sometimes called DERMAL BONES (flat bones of skull, clavicle) because membrane looks similar to dermis

Question 40

Clinical relevance of intramembranous ossification

Answer 40

there are some bones that are produced by this ossification; when someone has growth hormone excess, they growth in width and those bones are prone to growing more w/ this excess

Question 41

both methods of ossification:

Answer 41

- produce WOVEN BONE THAT IS THEN REMODELED | - produce bone that is, AFTER REMODELING, INDISTINGUISHABLE as forming from one method or the other

Question 42

Revew slides

Answer 42

16-18 on powerpoint