Quiz 1.3

Question 1

Functions of Bone

Answer 1

Protect vital organs
Support soft tissue
Produce RBCs
Reservoir for minerals (Ca)
Attachment site for skeletal muscle
System of machines to receive muscle torque and make movement

Question 2

Osteon

Answer 2

Allow cortical bone to remain rigid while receiving nutrients and removing waste
One “group of circles” in bone histology

Question 3

Bones comprised of

Answer 3

Bone cells and ECM

Question 4

Osteoblasts

Answer 4

Form bone matrix

Question 5

Osteocytes

Answer 5

Maintains bone tissue

Question 6

Osteoclasts

Answer 6

Resorbs bone

Question 7

Osteoprogenitor cells

Answer 7

Stem cells

Question 8

ECM composed of

Answer 8

Collagen fibers, inorganic materials

Question 9

Factors that influence mechanical properties of bone

Answer 9

Structure
Geometry
Mode of loading
Rate of loading
Frequency of loading
Muscle activity
Age

Question 10

Structure

Answer 10

Mineral (largest)
-Ca & P, compressive strength
Collagen, water (middle)
-tensile strength, some flex
Ground substance
-Gel surrounding collagen, compressive strength

Question 11

Geometry

Answer 11

Cross sectional area is proportional to failure point
Increase A = increase strength
Polar moment of inertia

Question 12

Polar moment of inertia

Answer 12

Distribution of bone tissue around neutral axis
Mass away from axis = increas PMI
Close to axis = decrease PMI
More dense = handle more force

Question 13

Mode of loading

Answer 13

Anisotropic: stiffness and strength depend on mode
Failure highest during Compression, then tension, then lowest at shear

Question 14

Why is failure lowest with shear

Answer 14

Because smallest SA along shear plane, bones not made for shear load

Question 15

Rate of loading

Answer 15

Visco-eleastic: Stiffness and strength depends on speed of load
High load rate: Increase stiff, increase failure point (increase E storage)

Question 16

Decreased loading rate

Answer 16

Slower app of force; cracking with NO fragments, little/no soft tissue damage

Question 17

Increased loading rate

Answer 17

Faster app of force; comminuted with displaced fragments, extensive soft tissue damage

Question 18

Viscoelasticity

Answer 18

Materials behave in elastic and viscous manners with different rates of loading
Higher loading rate, increase stiff
See graph

Question 19

Frequency of loading

Answer 19

Bones fatigue/weaken during repeated loading because fatigue process out paces repair
Factors: magnitude of load, number of load apps, number load apps in given time
See graph of injury

Question 20

Fatigue fractures

Answer 20

Stress fracture
High load, few reps
low load, many reps

Question 21

Muscle activity

Answer 21

Muscles may produce tensile or compressive stresses on bone, offset mechanical stress

Question 22

Aging

Answer 22

Decrease bone density with age, collage and mineral content decrease so does bone mass and size (Decrease stiff and strength)

Question 23

Bone remodeling

Answer 23

Increase bone density; alters size, shape, and structure based on imposed mechanical demands
Affected by activity level and implants

Question 24

Wolff’s law

Answer 24

Bone tissue is gained/lost depending on level of stress sustained.
Increase mechanical stress, increase bone tissue production