Biological Materials Flashcards

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1
Q

What are bones made up of?

A

Collagen (30% dry weight) - resist tensile loading

Minerals (70% dry weight) - resist compression

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2
Q

How much are bones capable to withstand compared to that of normal life?

A

6 times the amount

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3
Q

What are the two types of bones and which is stronger?

A

Cortical (outside) - strongest

Trabecular (inside)

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4
Q

What are the 2 different types of bone injury?

A

Traumatic - one-off

Fatigue Induced - stress related

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5
Q

What is Wolff’s Law?

A

Bones form in the reaction to the forces placed upon it

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6
Q

What are the 5 types of bone fracture?

A

1) Diaphyseal Impaction - axial compression
2) Transverse - bending
3) Spiral - torsion
4) Oblique Transfer - axial and bending
5) Oblique - axial, bending and torsion

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7
Q

How are transverse fractures caused?

A

Bending loads

Combination of forces causes the break to occur - cracks at right angles

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8
Q

What are the different types of cartilage?

A

Structure-less (hyaline cartilage in knee)

Contain connective tissue (fibrocartilage in ribs)

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9
Q

What is the percentage of weight that the collagen fibrils take up in the organic matrix?

What material makes you spongy?

A

10-30%

Proteoglycons suck up the water and make your joints spongy

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10
Q

What is anisotropic in relation to direction of loading?

A

If you apply force one way - the bones will respond the same way

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11
Q

How does cartilage show visoelastic behaviour?

A
  • Moves slowly and returns back to normal

- When loading it deforms and then increases size again

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12
Q

What are the different types of articular cartilage injuries? (3)

What happens during avascular cartilage?

A

Avascular - where there is no blood supply, it repairs slowly and shows no external signs.

Overuse Injuries –> cartilage wears away
High Impact –> cartilage swells

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13
Q

What are the 6 types of deep connective tissue?

What role does it play in the body?

A

1) Tendons –> cords of packed collagen
2) Aponeuroses –> spread out to improve more activity for a single muscle
3) Deep Fascia –> envelop individual muscles and bind them into groups
4) Intramuscular Septa –> separates muscle groups passing from deep fascia to the bone
5) Ligaments –> similar to tendons and contains elastin
6) Ligamentous Joint Capsules –> guide motion and prevent excessive motion - goes around the bone

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14
Q

Tendons:
What is its failure strain?
Where is the main site for energy return during elastic recoil? (E.g.)

A

8-10%

Achilles tendon - in basketball players its long but in rugby players its short

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15
Q

Ligaments:
What is their purpose?
What is the role of mechanoreceptors?

A

To cope with tensile forces (tension)

Mechanoreceptors initiate tension in nearby muscles to assist in maintaining joint stability

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16
Q

What are other examples of injuries? (3)

A

1) Sprains –> caused by excessive joint motion
2) Direct Blows –> stretching and permanent deformation
3) Ligament Failure –> bending and torsion to the distal limb

17
Q

What are the different types of ligament failure?

A

Mid Substance Tear @ fast loading rates

Bony Avulsion @ low load rates - where the ligament is stronger than the bone and just snaps off

18
Q

What are the effects of muscle tears?

A

1) Loss of stability
2) Joint misalignment
3) Abnormal Contact pressures
4) Loss of proprioception

19
Q

How far can muscles stretch past resting before they rupture?

A

160%

20
Q

How much more stiffness is an eccentric contraction more than concentric and why?

A

200x greater - the muscle always tries to shorten, so when a muscle is contracting eccentrically it still wants to shortern