Lecture 18 Flashcards

1
Q

What is whole body center of mass located on the body

A

Approx just in front of lumbosacral junction in standing posture

May move outside the body

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2
Q

What is center of gravity

A

The point through which the force of gravity acts on an object or system

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3
Q

COM and COG have the same…

A

Position

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4
Q

Tissue mechanics focuses on

A

Bones
Ligaments
Cartilage
Tendons

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5
Q

What is a load

A

An externally applied force

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6
Q

What are the different types of loading

A

Axial

Bending

Shear

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7
Q

What is axial loading

A

Loading acts along longitudinal axis of a body

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8
Q

What is involved in axial loading

A

Compression

Tension

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9
Q

What is compression

A

A load that squeezes the parts of a body together

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10
Q

What is tension

A

A load that pulls the parts of a body apart

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11
Q

What is bending loading

A

A load applied perpendicular to the longitudinal axis of a body causing a body to curve

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12
Q

What is involved in bending

A

Three point bending

Four point bending

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13
Q

What is three point bending

A

Three forces applied

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14
Q

What is four point bending

A

Four forces applied

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15
Q

What is the effect of bending determined by

A

Cross section area

Length of body

Distribution of the material around the neutral axis

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16
Q

What is area moment of inertia

A

Combined effect of cross section area and how it is distributed from the neutral axis

A measure of the bodys resistance to bending

17
Q

During bending what loading occurs on one side and what loading on the other side

A

Tensile loading on one side

Compressive loading on the other

18
Q

What is shear loading

A

Two forces are directed towards each other

But the forces are not along the same line and instead they are directed parallel to the surface of a structure

19
Q

What does shearing cause to happen to an object

A

Two surfaces to move in opposite parallel directions

Causes one part of the body to move parallel past another part

20
Q

What is Shear loading broken up into

A

Direct

Torsion

21
Q

What is torsional loading

A

Loads that exists when there is a twist around the neutral axis

22
Q

What is stress

What is the equation

What is the unit

A

The way a force is distributed within a body

Force / area

Unit N/m^2

23
Q

What is strain

A

The change in dimension normalized to the original dimension

24
Q

What is the equation of strain

A

Change in dimension / original dimension

25
Q

What is the equation for elastic modulus

A

Stress / strain

26
Q

What is strain energy

A

The amount of energy that the body can absorb as it deformed

27
Q

What is strain energy density

A

The amount of energy that can be absorbed by a normalised piece of tissue

28
Q

What is bones function

A

Provides a rigid framework that gives body shape

Functions as a set of rigid links and mechanical levers

Provides attachment sites for muscle tendon complexes

Protects the CNS and various internal organs

29
Q

What is bone mineral content

A

Total amount of mineral in bone

30
Q

What is bone mineral density

A

The mineral content in an area or volume of bone

31
Q

Overall strength of the bone is affected by

A

Bone mineral density

Where the bone is placed

32
Q

Bone is considered…

Why

A

Asymmetric

Bone is stronger in compression vs tension

Bone is stronger in tension vs shear

33
Q

Males have greater… (bone)

A

Peak bone mass

Rate of gain for bone mineral content

34
Q

Females have… (bone)

A

Transient decrease in bone mass around the menopause age of 45 - 60

35
Q

Bone is a what tissue

A

Dynamic

36
Q

Disuse and aging have what effect on bones

A

Inverse relationship with bone health

37
Q

Exercise has what effect on bones

A

Beneficial effect on mechanical properties of bone

38
Q

Weight bearing exercise has what effect on bones

A

Direct relationship with bone health

39
Q

Exercise should be: (in order to help bone health)

A

Dynamic loading

Moderate to high loading rate

Short duration

Long rest periods - allows tissue adaptation to new load