10-21a Connective Tissue Physiology and Response to Immobilization

Question 1

What is the structure of tendon fibers?

Answer 1

mostly in parallel

Question 2

What is the structure of ligament fibers?

Answer 2

somewhat parallel

Question 3

What is the role of type I collagen fibers?

Answer 3

absorb tensile forces

Question 4

What is the role of type III collagen? function?

Answer 4

flexibility/mesh

cross links to help with sliding motion and strength

Question 5

What cells lie within collagen?

Answer 5

fibroblast cells

trauma causes fibroblasts to turn into fibrocytes to become part of the healing process

Question 6

What are the other components of CT cells?

Answer 6

ECM: consistency and properties needed to function

water

elastin

GAGs: negatively charged, water-attracting, proteoglycans that help with lubrication and provide viscoelastic properties

Question 7

What is stress?

Answer 7

force/cross sectional area

Question 8

What is strain/deformation relationship?

Answer 8

how much can the tissue elongate as you apply stress to the tissue

Question 9

what is the toe stage and its properties?

Answer 9

□ Tissue is slack and crimped and begins to uncrimp here
□ Non-linear part of the stress strain curve
□ Where we are when stretching ligaments for daily motion

Question 10

what is the linear physiological range and its properties?

Answer 10

□ Elastic portion of stress strain curve
□ Can still return back to original length
□ Young’s modulus = slope of linear region/tissue stiffness

Question 11

what is the primary failure point and its properties?

Answer 11

loss of mechanical properties
□ Amount of stress goes beyond elastic threshold
□ Cannot return to original state
□ Plastic phase
® Once it goes beyond threshold (yield point), it cannot return to original length; elasticity reduces
□ Cross links are starting to break down and there is some micro failure within the ligaments and tendons

Question 12

What does complete failure involve?

Answer 12

reaching the ultimate failure point
tissues fail and lose their mech. properties
CI: how much load can the tissue take?

Question 13

What is creep?

Answer 13

the constant load that deforms the tissue over time
within tissues’ normal properties
applied within elastic range

Question 14

What is cyclic loading?

Answer 14

as you load and unload the tissues, they may follow a different pattern

Question 15

What is the clinical importance of cyclic loading?

Answer 15

measure of knee extension and then do it ten times/repeat the motion = better ROM

more reproducible after a few repetitions

Question 16

What is a grade I strain or sprain?

Answer 16

Grade I: some swelling, microtrauma, fatigue failure, constant repetitive loading of the tissues causes minor tear in collagen fibers, bonds break down
tendinopathy

Question 17

What does the grade of an injury tell you?

Answer 17

the degree of loading

Question 18

What is grade II?

Answer 18

no instability, continuity of tissues, beginning of breakdown and loss of parallel nature; addition of swelling and pain

Question 19

What is grade III?

Answer 19

unnatural trauma

breaking down of collagen fibers, mechanical properties change, macro-trauma, swelling, more instability of the joint

Question 20

What is microtrauma?

Answer 20

normal, parallel arrangement but reduced tensile properties

Question 21

what is macrotrauma?

Answer 21

ultimate failure point

over time, ultimate stress is greatly reduced

Question 22

What does the physical stress theory say?

Answer 22

injury causes changed thresholds
more activity can increase the tolerance of the tissue
loads applied to tissue before injury will be more harmful than you think after (dosing)