Flashcards in Biological Materials Deck (20):
What are bones made up of?
Collagen (30% dry weight) - resist tensile loading
Minerals (70% dry weight) - resist compression
How much are bones capable to withstand compared to that of normal life?
6 times the amount
What are the two types of bones and which is stronger?
Cortical (outside) - strongest
What are the 2 different types of bone injury?
Traumatic - one-off
Fatigue Induced - stress related
What is Wolff's Law?
Bones form in the reaction to the forces placed upon it
What are the 5 types of bone fracture?
1) Diaphyseal Impaction - axial compression
2) Transverse - bending
3) Spiral - torsion
4) Oblique Transfer - axial and bending
5) Oblique - axial, bending and torsion
How are transverse fractures caused?
Combination of forces causes the break to occur - cracks at right angles
What are the different types of cartilage?
Structure-less (hyaline cartilage in knee)
Contain connective tissue (fibrocartilage in ribs)
What is the percentage of weight that the collagen fibrils take up in the organic matrix?
What material makes you spongy?
Proteoglycons suck up the water and make your joints spongy
What is anisotropic in relation to direction of loading?
If you apply force one way - the bones will respond the same way
How does cartilage show visoelastic behaviour?
- Moves slowly and returns back to normal
- When loading it deforms and then increases size again
What are the different types of articular cartilage injuries? (3)
What happens during avascular cartilage?
Avascular - where there is no blood supply, it repairs slowly and shows no external signs.
Overuse Injuries --> cartilage wears away
High Impact --> cartilage swells
What are the 6 types of deep connective tissue?
What role does it play in the body?
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
What is its failure strain?
Where is the main site for energy return during elastic recoil? (E.g.)
Achilles tendon - in basketball players its long but in rugby players its short
What is their purpose?
What is the role of mechanoreceptors?
To cope with tensile forces (tension)
Mechanoreceptors initiate tension in nearby muscles to assist in maintaining joint stability
What are other examples of injuries? (3)
1) Sprains --> caused by excessive joint motion
2) Direct Blows --> stretching and permanent deformation
3) Ligament Failure --> bending and torsion to the distal limb
What are the different types of ligament failure?
Mid Substance Tear @ fast loading rates
Bony Avulsion @ low load rates - where the ligament is stronger than the bone and just snaps off
What are the effects of muscle tears?
1) Loss of stability
2) Joint misalignment
3) Abnormal Contact pressures
4) Loss of proprioception
How far can muscles stretch past resting before they rupture?