Mechanical Behavior of Tissues Flashcards
1
Q
What are the 7 various loading modes
A
- Unloaded
- Tension
- Compression
- Bending
- Shear
- Torsion
- Combined Loading
2
Q
What does bending create
A
Tension and compression
3
Q
What does torsion create
A
Tension on outside but compression on inside
4
Q
What is characterized by a wide dispersion of cells in the presence of a large extracellular matrix
A
Connective tissue
5
Q
What are the parts of CT at the microscopic layer (2)
A
- Interfibrillar component
2. Fibrillar component
6
Q
True or False:
CT are unique among body structures and function is determined by ECM
A
True
7
Q
What does blast mean
A
Creating, immature cell
8
Q
What does cyte mean
A
Mature cells
9
Q
What is interfibrillar composed of
A
Hydrated proteins
10
Q
What hydrated proteins make up interfibrillar (2)
A
- Proteoglycans (PGs)
2. Glycoproteins
11
Q
What make up proteoglycans
A
Glycosaminoglycans (GAGs)
12
Q
What are glycosaminoglycans
A
Polysaccaride chains
13
Q
What are examples of glycosaminoglycans (3)
A
- Chondroitin
- Chondroitin sulfate
- Hyaluronon
14
Q
True or False:
The proportion of PGs in extracellular matrix effects hydration
A
True
15
Q
What charge do GAGs have
A
Negative
16
Q
What does GAGs having a negative charge do
A
Causes PGs to cause swelling pressure leading to flow of water into matrix
17
Q
What resist and contain the swelling
A
Collagen fibers
18
Q
Tissues subjected to high compression forces have a blank PG content
A
High
19
Q
Tissues subjected to high tensile forces have a blank PG content
A
Low
20
Q
What are the 2 major components of Fibrillar
A
- Collagen
2. Elastin
21
Q
What is the most abundant protein in the body
A
Collagen
22
Q
Most common types of collagen fibers
A
I and II
23
Q
What allow the fibers to deform under force and return to original state
A
Elastin
24
Q
What color is elastin
A
Yellow
25
What are some characteristics of elastin and collagen
Sparsely vascularized, parallel fibers, and DCT in tendons and ligaments
26
True or False:
| DCT require a longer resistance hold to lengthen than muscle
True
27
What do fibroblasts synthesize
Procollagen
28
What happens to procollagen
It is cleaved extracellularly to produce type I collagen
29
Which way is each polypeptide chain coiled
Left handed
30
How many alpha chains are coiled together in a right handed helix
3
31
What are cross links formed by
GAGs between collagen molecules
32
True or False:
| All biological tissues posses viscoelastic properties
True
33
What would happen if low amount of elastin in tendon
Easy sprains
34
What would happen if large amount of elastin in tendon
Delayed muscle contractions
35
What has more elastin tendons or ligaments
Ligaments
36
Who found that there is 2:1 elastic to cartilage ratio in the ligamentum flavum
Nachemson and Evans
37
What does the 2:1 ratio of the ligamentum flavum do
Provides a preload to motion segments
38
Tissues increase their structural or functional capability in response to overloading (stimulus response)
Overload
39
What is the overall idea of overload
To make tissue you must stimulate the tissue
40
Specific stimulus for adaption elicits specific structural and functional changes in specific elements
Specificity
41
Specificity overall idea
Task specific (meets demands of the task)
42
discontinuing training stimulus will result in de-training and the adaptive changes regress
Reversibility
43
Reversibility overall idea
stop training leads to disuse atrophy
44
What does SAID stand for
Specific Adaptions to Induce Demands
45
True or False:
| Too much or too little overload is bad
True
46
How do you strengthen cartilage
Compressive loads because it's function is to resist compression
47
What is the property of a material or structure to return to its original form following removal of deforming load
Elasticity
48
Overall idea of elasticity
An object will stretch and then return back to its original state
49
What is the property of a material to deform permanently when its loaded beyond its plastic range
Plasticity
50
Overall idea of plasticity
Property of an object to stretch and maintain the shape
51
What is the property of a material to resist loads that produce shear, controls fluid rate of flow
Viscosity
52
True or False:
| Viscosity is the solid property and elastic materials is the fluid property
False
53
When is energy released and stored
Released: during unloading
Stored: during loading
54
True or False:
| Higher rate forces do not have time to dissipate rapidly through the cracks
True
55
True or False:
| Low rate forces also do not have time to dissipate rapidly through the cracks
False
56
Which results in more tissue damage low rate or high rate
High rate
57
What is the creep phenomenon
Load is suddenly applied and then held constant over time
58
What load
Stress
59
What is deformation
Strain
60
True or False:
| Deformation reaches equilibrium
True
61
Stress relaxation is a constant what
Strain
62
During stress relaxation and creep what is held constant
Deformation
63
True or False:
| The force required to maintain deformation decreases overtime
True
64
What happens during cyclic loading
Tissue stretches and returns back to original
65
Is cyclic loading elasticity or plasticity
Elasticity
66
What happens to the load overtime
The load required to lengthen the tissue decreases
67
How do you get greater ROM but not stretching
Golgi tendon organ stimulation and heating up tissue
68
Elongation is what
Strain or deformation
69
What is all about plasticity
Hysteresis
70
What does the area under the hysteresis curve represent
Energy or heat loss during change
71
What does the bottom of the stress strain curve equal
Toe region
72
What does the middle of the stress strain curve equal
Elastic zone
73
What does the almost top region equal in the stress strain curve
Yield point/yield stress
74
What does the tippy top of the stress strain curve equal
Rupture
75
What is the toe region
Straightening out the fibers, takes a little load to straighten
76
What is the elastic zone
If you keep a tissue in this zone and release it will go back to the original state
77
What is the yield point/stress zone
Load at which it will not be elastic and will be plastic
78
What is the rupture zone
Point where rupture of tissue would occur
79
What is the plastic zone
The area between the yield point/stress zone and rupture zone
80
What happens if you spend too much time in the elastic zone
Atrophy
81
What happens if you spend too much time in the yield point/yield stress
Wear and tear
82
How does tendon loading differ from other CT
It is attached to skeletal muscle
83
What does muscles and tendons being in series mean
You pull on the tendon you pull on the muscle
84
Where do muscle strains most commonly occur
Myotendinous junction
85
How much stronger is the tensile strength of tendon when compared to muscle
twice
86
What is more common muscle rupture or tendon rupture
Muscle rupture
87
Normal tendon loading is typically what percent of the actual load a tendon can resist
5-10%
88
What are the 3 layers of a tendon
1. Paratenon
2. Eiptenon
3. Endotenon
89
What is the layer directly covers the tendon
Paratenon
90
What is continuous with the perimysium and periosteum
Endotenon
91
What is synovial tissue only in high friction locations
Epitenon
92
Is epitenon found in every tendon
NO
93
What are fibers that come down into the bone from the tendon
Sharpey's fibers
94
What happens to the body's ability to retain water as we age
It decreases
95
What does the decreased ability to retain water lead to
increased tissue stiffness
96
What is the most common way a patient will strain a muscle
eccentrically
97
What age group is most likely to tear their achillies tendon
35 to 55 year old males
98
What phase of healing corresponds to remodeling
Maturation
99
What phase of healing corresponds with cellular reaction
Inflammatory
100
What phase of healing corresponds with collagen synthesis
Proliferation
101
True or False:
| Mobilization of a tissue should occur as early as possible and does not need to be controlled
False
102
True or False:
| We need controlled rest of the specific joint in question not the surrounding joints
True
103
What does immobilization in tendons do
Reduces water content, PG content and strength
104
What does reducing water in the tendons do
Increase stiffness, decrease compliance, and increase strain
105
How long does it take immobilization of ACL to weaken bone-ligament-bone complex
8 weeks
106
When is tendon softening most pronounced with immobilization
1-2 weeks
107
What are the thingsto remember about the myotendinous junction (3)
1. Adhesion
2. Force transmission
3. Force must not exceed strength of interface and adhesion
108
What is failure at epiphysis
Pre-epiphyseal closure
109
What is failure at the myotendinous junction
Post-epiphyseal closure
110
What tear of bone ligament bone are most common in adults
Midsubstance tear
111
What does the pre-epiphyseal closure represent
Growing years
112
What does the post-epiphyseal closure represent
Growth is done
113
What do you need to remember force stretching connective tissue (5)
1. Optimal intensity
2. Duration
3. Temperature
4. Timing/sequencing
5. Frequency
114
What must be present to prescribe exercise (4)
1. Mode
2. Intensity
3. Frequency
4. Duration
115
What is the most appropriate duration of loading peri-articular DCT
Low load for several minutes (5 or more)
116
What do nonthrust manipulations do (3)
1. Enhance synovial fluid
2. Stimulate mechanoreceptors which inhibit nociceptors
3. Enhance mobility
117
What is the optimal duration for muscle lengthening
30 seconds
118
What must be done to insure lengthening occurs during the 30 seconds
Move further into the stretch as time goes away
119
What is the general frequency of exercises
2-3 or 3-5 times a day 7 days a week
120
Example of how altering tissue temperature can lead to change in lengthen
Heat up tissue and stretch then cryotherapy to freeze it in place
121
Parameters for strength
6-12 reps
| 3-5 sets
122
Parameters for endurance
20-30 reps
| 3-5 sets
123
Parameters for tendon
30-40 reps
| 3-5 sets
124
Parameters for ligament
1000's of reps
125
Parameters for cartilage
Hours of reps
126
Who set the standards for these parameters
American College of Sports Medicine (ACSM)
127
True or False:
| The most important reps are the fatigue/burn reps
True
128
True or False:
| Cartilage is avascular, aneural, and has a low metabolic rate
True
129
What does cartilage being aneural mean
Don't feel it
130
What does cartilage being avascular and having a low metabolic rate mean
Slow healing
131
What are the fiber orientations of cartilage from top down
Surface: Thin horizontal fibers
Middle: Tangential fibers
Bottom: Vertical fibers
132
What does shear force do to the top layer of cartilage
Causes them to thin and wear away
133
What is the thickest possible cartilage
5mm
134
What happens to the superficial layer of cartilage as we age
We lose it from wear and tear
135
What are the uncalcified layers of cartilage
Middle and Deep
136
What is the tide mark
Demarkation between uncalcified and calcified cartilage
137
True or False:
| The tide mark advances with age
True
138
True or False:
| As we age cancellous bone enlarges pushing the tide mark further up
True
139
If cartilage can't feel anything how does osteoporosis cause pain
Cartilage isn't able to stop all of the compression so some of the force is sent to the bone which causes pain
140
What do chondrocytes do
Make and secrete matrix inhibiting cell to cell contact
141
What is the most important characteristic of cartilage
Fluid component
142
What happens to water content and PG content as you go deeper into tissue
Water content decreases and PG content increases
143
What is the solid component of cartilage
Porous, permeable matrix of type II collagen and PG
144
Does the solid component of cartilage have an extremely high or low permeability coefficient
Low
145
What does a low permeability coefficient mean
Slow influx and eflux of fluid
146
What is an anisotropic tissue
Solid and semisolid materials (Heterogeneous CT)
147
Do anisotropic tissues tolerate forces in all directions
No
148
True or False:
| We respond to the forces imparted on us
True
149
What is chondroomalasia
Softening of cartilage
150
What is an isotropic tissue
Materials display the same mechanical behavior despite the direction of the forces (resist forces in all directions)
151
What is an example of an isotropic tissue
Steel
152
Are isotropic tissues homogeneous or heterogeneous
Homogeneous
153
Where does the stress develop in articular cartilage
Collagen-PG solid matrix
154
What generates the frictional drag in articular cartilage
Interstial fluid flow through the matrix
155
Why is frictional drag good in articular cartilage
Slows down the compression force
156
What is an indicator of tissue permeability
Rate of creep
157
What type of pores result in low permeability and high friction to flow
Small pores
158
True or False:
| Compression further reduces pore sizes
True
159
True or False:
| The volume of fluid stays constant in joint cavity
True
160
What happens as you go from sitting to standing
Fluid is forced through the small pores
161
Why does movement of fluid in joint cavity need to be cyclic
To get rid of waste
162
What is the mode for cartilage training
Cyclic loading
163
True or False:
| It is very unlikely to have bone on bone contact
True
164
True or False:
| Load and permeability have an indirect relationship
True
165
What happens to the macromolecules of cartilage as we age (3)
1. Decreased aggregation
2. Decreased GAG content
3. Shorter chains
166
Structural modifications may be linked to what
Changes in chondrocyte synthetic function
167
What does pH decreasing cause
Decreased charge groups, which results in decreased repulsive force
168
What does increased [salt] cause
Increase positively charge molecules resulting in charge shielding, and decreasing repulsive force
169
What is the biphasic creep response in compression (3)
1. Rapid initial exudation of fluid from articular surface
2. Collagen and PGs resist the creep created by the compressive load
3. Fluid exudation occurs until deformation equilibrium is reached
170
Why does rapid initial exudation of fluid occur
Because the load came on rapidly and pores didn't have time to get smaller
171
What causes deformation to be in equilibrium
pore size getting smaller with time
172
How long does it take for cessation of fluid flow to occur
4-16 hours
173
What is biphasic stress relaxation response (2)
1. Stress is increased until a given deformation is reached and deformation/strain is maintained
2. Stress decreases under constant strain until equilibrium stress is reached
174
What is fluid redistribution responsible for
Tissue stress relaxation
175
Rapid redistribution of load throughout tissue reduces what
Peak stresses
176
What is PG washout
Lose PG as we age, which decreases the repulsive nature of PGs
177
What does PG washout result in
Pore size to be greater and shock absoprtion decreases
178
What are the 2 types of articular cartilage lubrication systems
1. Boundary
| 2. Fluid
179
What lubrication system is each load bearing surface is coated with lubricin (2 surfaces don't touch)
Boundary
180
When is the boundary lubrication system most effective
Low loads, low speeds, long durations
181
What lubrication system is a film of fluid interposed between 2 joint surfaces
Fluid
182
What are the 4 types of fluid lubrication
1. Hydrostatic
2. Hydrodynamic
3. Squeeze Film
4. Elastohydrodynamic
183
What is hydrostatic lubrication
Film of lubrication that is maintained under pressure and occurs when you aren't moving
184
Hydrostatic lubrication occurs with what type of force
Non parallel force
185
When is hydrostatic lubrication most effective
High loads
186
What is hydrodynamic lubrication
Wedge of fluid is created when non parallel opposing surfaces slide on one another
187
What does hydrodynamic lubrication cause
Lifting pressure occurs in wedge and increased viscosity keep surfaces apart
188
What is an example of hydrodynamic lubrication
Hydroplaning
189
What is squeeze film lubrication
Pressure created in fluid film by surfaces moving that are perpendicular to one another
190
When is squeeze film lubrication most effective
High loads and short duration
191
What type of force causes squeeze film lubrication
Perpendicular orientation
192
What happens during squeeze film lubrication
Fluid is squeezed out which increases viscosity of fluid
193
What is elastohydrodynamic lubrication
Fluid film is maintained at a uniform thickness by elastic deformation of articular surfaces and adequate layer of fluid remains
194
What are the 3 types of aberrant lubrication systems
1. Adhesive wear
2. Abrasive wear
3. Fatigue wear
195
What is adhesive wear
Osteochondritis dessicans
196
What is osteochondritis dessicans
Complete or incomplete separation of a portion of cartilage and bone
197
What is abrasive wear
Joint mouse (loose body) irritation
198
What is a way to think of abrasive wear
Rocks in dryer
199
What is fatigue wear
PG washout, aging, DJD
200
True or False:
| Any of the 5 lubrication systems can occur in any joint
True
201
What are some causes of loss of PG matrix (6)
1. Prolonged immobilization
2. NSAIDS
3. Trauma
4. Surgery
5. Infection
6. Aging
202
Loss of PG matrix can be reversible dependent upon degree and duration
True
203
What layers does softening occur in for chondromalacia
3 and 4
204
What does softening occurring in layer 3 and 4 mean
Visualization of pathology is difficult
205
Too much stress equals what
DJD
206
Too little stress equals what
Chondromalacia
207
What is the intensity for intervention of articular cartilage growth (3)
1. Pain as a guide
2. Edema or effusion as a guide
3. Full body weight loading may be excessive
208
What is the duration/frequency for articular cartilage
High repetition (100's-1000's) of cyclic loading
209
What is the mode of intervention for articular cartilage
Attempt to mimic function and minimize combinations of shear and compression (closed chain exercises)
210
What are the functions of bone (4)
1. Protection for internal function
2. Rigid levers for attachment
3. Harbors hemopoietic tissue
4. Resevoir for calcium, phosphate, and other ions
211
What are the key features of bone structure (4)
1. Highly vascular
2. Innervated
3. Dynamic CT
4. Capable of repair and remodeling
212
True or False:
| You are constantly laying down bone and reabsorbing it
True
