Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

PTY1016 FOP 1 > Biomechanics (tissues) > Flashcards

Biomechanics (tissues) Flashcards

1
Q

What are the types of forces on the musculoskeletal system?

A
  1. Tension
  2. Compression
  3. Bending
  4. Shear
  5. Torsion
  6. Combined loading
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What is tension?

A

Forces are from opposite directions

(Pulling two ends apart)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What can overload with ‘tension’ cause?

A

Sprains, strains, (sometimes) peripheral nerve injury

E.g. hamstring tear

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What is compression?

A

Forces moving in an approximating (similar) direction

(pushing two ends towards e/o)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What can overload with ‘compression’ cause?

A

fractures
(sometimes) disc damage/nerve compression

E.g. stress fracture of vertebrae, disc herniation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What is bending?

A

Force that produces tension on one side of the body’s longitudinal axis and compression on the other side

legit just bending

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What is shear?

A

Combination of tension and compression

forces NOT moving in opposite or approximating (similar) directions exclusively

tbh, the forces look like they from opp sides (like upper part has force from side A, lower part has force from side B)

E.g. ACL ruptures

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What is torsion?

A

Force applied in twisting

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What is combined loading?

A

When loading results in more than one type of stress (force)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What is stress?

A

A physical quantity
An external force

Force per unit area applied to the material

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What is strain?

A

Stresses lead to strain (deformation)
E.g. putting pressure on an object causes it to stretch

Strain is a measure of how much an object is being stretched

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

How to calculate stress?

A

Force/cross-sectional area

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

How to calculate strain?

A

Elongation/original length

Basically: new length - original length/original length

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What is elastic modulus?

A

calculate = Stress/Strain

indicator of an object’s likelihood to deform when a force is applied

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Look at slide 8 of mechanics biological tissues notes (stress-strain curves)

A

HAVE YOU LOOKED AT IT?

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What are the three regions in the stress-strain curve?

A
  1. Initial linearly elastic region
  2. Intermediate region
  3. Final region
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What is initial linearly elastic region?

A

Where the
slope = elastic modulus

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What is the intermediate region?

A

Exhibit yielding & nonlinear elasto-plastic material behaviour

Strain hardening; entering plastic phase

Basically, being stretched & deformation can become permanent

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What is the final region?

A

Exhibits linear plasticity where slope = strain hardening modulus

Necking
Until failure

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What is plastic behaviour?

A

An object or material has plastic behavior when stress is larger than the elastic limit

Basically, when stress is removed, the object doesn’t return to original (deformation is permanent)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

What is uncrimping?

A

Taking up slack
From slack to straight

E.g. flabby resistance band; you pull it straight BUT not stretched yet

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

`Look at slide 10 of mechanics biological tissues notes

A

HAVE YOU LOOKED AT IT?

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

What happens at the toe phase (0-2%)?

A

Uncrimping: takiing up the slack (from slack to straight with NO stretch at all)

Macroscopic slack (bc not homogenous)

Needs more force to bring about deformation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

What happens during the linear stretch (~2-5%)?

A

Elasticity (tissues will be stretched according to force applied)

Start of plasticity halfway through (abit)

Therapeutic range (around 4-6%)

Viscoelasticity
Force
Relaxation
Creep
Hysteresis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

What happens during the primary failure phase (5-8%)

A

Part of the therapeutic range (until ~6%)
Viscoelasticity
Plasticity
Force
Creep
Relaxation

1-2 degree injury (aft the end of therapeutic range = injuries!)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

What happens during total failure phase (after 8%)?

A

Influenced to failure
basically, total failure (e.g. ligament tear)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

What is viscoelasticity?

A

Materials that show viscous & elastic characteristics when undergoing deformation (time-dependent)

All connective tissues are viscoelastic materials (basically - fluid-like component in their behaviour)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

What is viscosity (viscoelasticity)?

A

Material’s resistance to flow (a fluid property - there’s fluid phase & solid phase)

High viscosity fluids: flow slowly (e.g. honey)
Lower-viscosity fluids: flow quickly (e.g. water)

↓es w temperature (easier to flow; e.g. use of heat before stretching)

↓es w slowly applied loads

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

What is elasticity (viscoelasticity)?

A

Material’s ability to return to its original length/shape aft removal of deforming load

Length changes/deformations proportional to applied forces/loads

When stretched, work is done (force x dist) = energy in stretched material inc.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
30
Q

What does elasticity depend on?

A

Depends on collagen & elastin amounts

If more elastin = stretch better
if more collagen = more difficult to stretch

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
31
Q

What are the time- and rate-dependent properties?

A
  1. creep
  2. stress-relaxation
  3. strain-rate sensitivity
  4. hysteresis
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
32
Q

What is creep?

A

Progressive strain (deformation) of a material when under a constant load over time

Basically, deformation increases as (fixed/constant) force increases. When force removed, tissue recovers to original length in nonlinear manner

E.g. gravitational force on body. Stand whole day, gravitational force on vertebral column = intervertebral discs squashed; but sleep (supine) = force is removed (?) = taller

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
33
Q

Example of creep

A

Gravitational force on body.

Stand whole day, gravitational force on vertebral column = intervertebral discs squashed; but sleep (supine) = force is removed (?) = intervertebral discs return to normal position = talller

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
34
Q

What is stress relaxation?

A

Reduction of stress within a material over time as the material is subjected to a constant deformation

Stress generally ↓ w time (therefore relaxation)

BASICALLY, stretch in same position for long period = becomes easier = then can stretch further

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
35
Q

Examples of stress relaxation

A

Stretch until the force drops then stretch some more = achieves the overlap b/w elastic & plastic phase = permanent change

Serial casting = stretch the tissue to max & cast it (at max range) = next day, push more & cast again & so on

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
36
Q

What is hysteresis?

A

When force is applied (loaded) and removed (unloaded) to a structure, the resulting load-deformation curves do not follow the same path

NOT all energy gained due to lengthening work (force x dist) is recovered during exchange from energy to shortening work (some energy lost, as heat)

BASICALLY, deformation does not return to original (still stretched) bc energy recovered is less

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
37
Q

What is strain-rate sensitivity?

A

Tissues behave differently if loaded at different rates

*subsequent stress-relaxation will be LARGER if load applied fast
**Creep will take longer to occur if rapid loading

basically how fast/slow you apply stress

38
Q

What happens to strain-rate sensitivity if load is applied rapidly?

A

Tissue is stiffer
larger peak force can be applied to tissue
Need more force since stress is lower

Fast = strain not that strong = need more force

39
Q

What are the biological tissues?

A

Hard: bone, teeth
*Soft: tendons, ligaments, joint capsules, skin, muscles, articular cartilage

40
Q

Phases of a bone fracture

A

Acute phase: Week 1-2
Sub-acute phase: Week 2 - Month 3
Chronic: After month 3

41
Q

What happens in a fracture?

A

Just read through and agar agar know:
1. blood pours into injured area to form a clot - aka fracture haematoma (scaffold for migration of cells & source of growth factors)
2. granulation tissue gives rise to the callus = acts like a protective cast
3. endochondral ossification - soft callus converred to hard bony framework
4. Callus remodelled so thaat cartilaginous structure converts to calcified bone matrix & bone is shaped to near-normal shape

42
Q

Purpose of bones

A
  1. supports & protects internal organs
  2. assists movement: sites for muscle attachment & facilitates muscle actions & body movement
  3. mineral “bank” : reservoir for calcium deposit = maintain homeostasis of bld calcium
  4. blood cell production
  5. adipose tissue (yellow marrow)
43
Q

Types of bones

A
  1. Long bone (e.g. humerus)
  2. Short bone (e.g. carpal bone)
  3. Irregular bone (e.g. vertebra)
  4. sesamoid bone (e.g. patella, sesamoid of thumb)
  5. Flat bone (e.g. sternum)
44
Q

Composition of bones

A

Most to least:
Calcium
Organic compounds (mostly collagen)
Phosphate
Carbonate
Magnesium
Sodium & Potassium

45
Q

What are the two types of bone tissue?

A

Cortical (aka compact) bone tissue

Cancellous/trabecular (aka spongy) bone tissue

46
Q

What are cortical (compact) bone tissues?

A

Dense material forming outer shell (cortex) of the bones

47
Q

What are cancellous/trabecular (spongy) bone tissue?

A

Consists of thin plates (trabeculae) in a loose mesh structure enclosed by cortical bone

48
Q

What are bones covered by?

A

Dense fibrous mbn - periosteum

Covers the entire bone except for joint surfaces

49
Q

What are joint surfaces covered by?

A

articular cartilage

50
Q

Spongy bone vs compact bone

A

Aka: Cancellous tissue vs cortical tissue

Area: spongy makes up inner cavity of bone while compact is the outer covering

Porosity: spongy more porous than compact

Functional unit: functional unit of spongy is trabeculae while compact is osteons

51
Q

What are the major factors influencing mechanical behaviour of bone?

A
  1. Composition of bone
  2. Mechanical properties of tissues comprising the bone
  3. Size & geometry of bone
  4. Direction, magnitude & rate of applied loads
52
Q

What can bones be characterised as (3 points)?

A
  1. Nonhomogenous material: consists of cells, organic & inorganic substances w diff material properties
  2. Anisotropic (direction dependent): direction of force applied affects behaviour
  3. Viscoelastic (time & rate dependent): bone can resist rapidly applied load better than slowly applied loads (basically bone is stiffer & stronger at higher strain rates)
53
Q

What are the effects of anisotrophy?

A

Stress-strain behaviour dependent on orientation of bone w respect to direction of loading

If force is applied longitudinally (e.g. top down like in walking/standing), stronger & stiffer (larger elastic modulus)

If force applied transversely (e.g. 90 degree to the bone), more brittle & weaker

Note: in soccer/muay thai, there may be transverse force but if it’s fast (e.g. kick), more force is needed

54
Q

What is the viscoelastic property of bone?

A

Brittle: material fails before permanent deformation

Ductile: material deforms greatly before failure (to do with stiffness)

55
Q

What are the factors affecting integrity of bone (4 points)?

A
  1. Osteoporosis
  2. Surgery
  3. Bone defects
  4. Screw holes for pins & bone plates
56
Q

How does osteoporosis affect integrity of bone?

A

Reduces bone integrity in terms of strength & stiffness by reducing apparent density

57
Q

How does surgery affect bone integrity?

A

Alters normal bone geometry
May cause leg length difference = some muscles may be shorter = muscle imbalance

58
Q

How do bone defects affect integrity of bone?

A

Usually congenital
e.g. genu valgus/varus

59
Q

How does screwing holes for pins & bone plates affect integrity of bone?

A

Causes stress concentrations on bone (abnormal force)

60
Q

What is osteoporosis characterized by?

A

Low bone mass
Deterioration of bone micro-architecture
Compromised bone strength

most epidemic bone dz in older populations

61
Q

What does osteoporosis lead to?

A

Bone fragility
Increased risk of fracture under low loads

62
Q

Types of soft tissues (6 points)

A
  1. Articular cartilage
  2. tendon
  3. ligament
  4. muscle
  5. joint capsules
  6. skin
63
Q

Collagen fibres

A

Not effective under compression
Individual fibrils of collagen fibers surrounded by gel-like ground substance (mainly water)

Possess two phases: solid-fluid OR viscoelastic material behaviour

63
Q

What is the composition of soft tissues?

A

All soft tissues are composite (made up of 2 or more materials) materials

Main structural elements:
Collagen fibres: gives structure & stiffness
Elastin fibres: thinner & cross-linked; can be crimped/uncrimped

64
Q

What happens to collagen fibres when stretched & released?

A

When stretched: energy stored in fibre like a spring

When released: releases energy & fibre returns to its unstretched state

64
Q

Elastin fibres

A

Fibrous protein whose material properties resemble the properties of rubber

Elastin + microfibrils form highly extensible elastic fibres that are reversible at high strains

65
Q

Difference in behaviour of elastin fibres & collagen fibres

A

Elastin fibres possess low-modulus elastic material property (not stiff)

Collagen fibres show a higher modulus viscoelastic behaviour (stiffer)

66
Q

Collagen vs Elastin

A

Found in: collagen in skin & protective tissues (e.g. joint capsule); elastin in connective tissue of elastic structures

Abundance: collagen 3rd most abundant protein; elastin less abundant

Colour: collagen white; elastin yellow

Purpose: Collagen gives strength to structures; elastin provides elasticity to structures

Production: collagen produced until ageing process; elastin produced mainly in fetal period

67
Q

Viscoelastic model comprises:

A

A spring: models elastic behaviour
A dashpot: models time dependent behaviour

68
Q

Movement of body segments (skeletal muscles)

A

Achieved as a result of forces generated by skeletal muscles which convert chemical energy into mechanical work

69
Q

What are skeletal muscles composed of?

A

Muscle fibres & myofibrils

70
Q

What kind of material behaviour does skeletal muscles exchibit?

A

Viscoelastic material behaviour (bc have both collagen & elastin)

Muscles are viscous in a sense bc no internal resistance to motion

71
Q

What is muscle contraction?

A

development of tension in the muscle

concentric, eccentric & isometric contractions

72
Q

What is flexibility of the human body due to?

A

Joints
articulations
skeletal system

(therefore, after surgery/injury, must stretch the joints (some force = some deformation); if lie down whole day, tissues shorten = become tight = problem)

73
Q

What are the two primary functions of joints?

A

Mobility
Stability

74
Q

Structural classification of joints (3 points)

A

FIbrous joints
- dense connective tissue connect bones
- b/w bones in close contact

Cartilaginous joints
- hyaline cartilage/fibrocartilage connect bones

Synovial joints
- most complex
- allow free movement

75
Q

Functional classification of joints (3 points)

A

Synarthrotic joints
- considered immovable

amphiarthrotic joints
- slightly movable

diarthrotic joints
- freely movable

76
Q

Look at slide 54 of mechanics biological tissues notes

A

HAVE YOU LOOKED AT IT?

77
Q

Glenohumeral joint

A

Ball-and-socket joint
Enables arm to move in 3 planes (triaxial motion)

  1. High level of mobility
  2. Reduced stability
  3. Increase vulnerability of joint to injuries (e.g. dislocations)
78
Q

Humeroulnar joint

A

Movement only in one plane (uniaxial motion)
More stable
Less prone to injuries than shoulder joint

79
Q

What are the functions of articular cartilage (4 points)?

A
  1. Covers articulating surfaces of bones at diarthrodial (synovial) joints (if X there, wear & tear)
  2. Provides weight bearing surface w low friction & tear
  3. facilitates relative movement of articulating bones
  4. distributes loads over larger contact area (reduces stress applied to bones)
80
Q

What happens to the articular cartilage under tension?

A

Cartilage responds by realigning the collagen fibres which carry the tensile loads applied to tissue

81
Q

What are shear stresses on the articular cartilage due to?

A

Frictional forces (2 surfaces rubbing on e/o) b/w the relative movement of articulating surfaces

82
Q

What are the changes of the joints over time (lifespan changes)?

A
  1. Joint stiffness in older people
  2. Fibrous joints change first
  3. Symphysis joints may change in the vertebral column (water loss from intervertebral discs) = loss of disc height & flexibility
  4. Synovial joint loses elasticity
83
Q

What are tendons?

A

Fibrous connective tissues
Execute joint motion by transmitting mechanical forces from MUSCLES TO BONES

Passive tissues (cannot contract to generate forces)

84
Q

What are ligaments?

A

Fibrous connective tissues
Attaches bones to to another bone across a joint

85
Q

Tendons compared to muscles

A

Tendons are stiffer, have higher tensile strength & can endure larger stresses

86
Q

What do tendons enable muscles to do?

A

Enables muscles to transmit forces to bones without wasting energy to stretch tendons

87
Q

What is the purpose of ligaments?

A

Guide & stabilise skeletal joint movement
Prevent excessive motion

88
Q

Ligament vs tendons (elastic fibres)

A

Ligaments have a greater proportion of elastic fibres = higher extensibility BUT lower strength & stiffness

Also viscoelastic & exhibits hysteresis

89
Q

Difference between tendon & ligament

A

Main function: tendon connect muscle to bone; ligament connect bone to bone at joints

Toughness & elasticity: tendon tougher; ligament more elastic

Injuries: tendon - tenosynovitis, avulsion (w fracture), tendinitis (mostly inflammation); ligament - sprains & torn ligament

Formation: tendon - modification of the white fibrous tissues; ligament - formed with yellow elastic tissue modification along collagen fibres

PTY1016 FOP 1 (16 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions