Tissue Flashcards by Shyanne Howard

which is more likely to rupture, muscle or tendon? Why?

-Muscle b/c tendon tensile strength 2x >muscle
-Tendon loading 5-10%

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what is the injury & repair in tendon during the inflammation phase?

Cellular Reaction

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what is the injury & repair in tendon during proliferation?

Collagen Synthesis

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what is the injury & repair in tendon during maturation?

Remodeling

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what does immobilization of tendon do to water content, PG/GAG & strength?

Reduces

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where do muscle-tendon injuries most commonly occur & from what?

Myotendinous Junction
Due to stretching or combined stretching & contraction

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what are age dependent behaviors of muscle tendon & Bone-Ligament-Bone failure under tension?

-Pre-epiphyseal closure (failure at epiphysis)
-Post-epiphyseal closure (failure at MTJ)
- Clinically mid substance tears of Bone-Ligament-Bone more common in adults

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describe articular cartilage clinically relevant features/

-Avascular
-Aneural
-Tissue w/ low metabolic rate

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what is articular cartilage designed to withstand?

-Rigorous loading w/o failure
- To distribute loads
-To provide low friction surface

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describe the fluid compartment of articular cartilage?

-Key both structurally & mechanically in hydraulic tissue
-Water content decrease & PG content increased w/ increased depth of tissue

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Describe the solid compartment of articular cartilage?

-Porous, permeable matrix primarily of type II collagen & PG
-Anisotropic tissue (Heterogenous CT)

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what is the visco-elastic response of articular cartilage?

-Stress developed in collagen-PG solid matrix
-Frictional drag generated by interstitial fluid flow through matrix
-Greater PG aggregation = increase elastic response & rupture strength
-Aging reduces degree of PG aggregation

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describe the mechanical behavior of permeability?

-Rate of creep is an indicator of tissue permeability
-Small pores result in low permeability & high friction to flow
-Compression further reduces pore size

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what does aging due to structural macromolecules?

-Decreased GAG content & shorter chains
- Structural modification may be linked to changes in chondrocyte synthetic function

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what is the creep response to compression?

-Rapid initial exudation of fluid from articular cartilage
-External compressive load creates creep, resisted by stress developed in collagen-PG solid matrix & frictional drag

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what happens after prolonged compression to articular cartilage?

-Continued slower exudation until deformation equilibrium reached
-External compressive load ultimately equals stress developed in collagen-PG solid matrix alone

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about how long does healthy cartilage take until it ends fluid flow?

4-16 hours of constant load

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what is the response of stress-relaxation to articular cartilage?

-Stress is increased until deformation is reached & then deformation/strain maintained
-Stress decreases under constant strain until equilibrium stress is reached

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what is fluid redistribution responsible for?

tissue stress relaxation

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what does rapid redistribution of load throughout articular cartilage do?

-Reduced peak stresses & contributes to articular cartilage resilience

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what is the AC lubrication system (Boundary)?

-Each load bearing surface is coated w/ lubricin (diarthrodial joints) = 2 surfaces don’t touch one another

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when is the boundary ac lubrication system most effective?

-At low loads

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what is the AC Lubrication system (Fluid)?

-Film of fluid interposed b/w 2 joint surfaces

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what is adhesive wear?

-Osteochondritis dessicans (complete or incomplete separation of a portion of cartilage & bone)

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what is abrasive wear?

joint mouse irritation

what is fatigue wear?

PG washout, aging, DJD

what causes loss of PG matrix?

Prolonged immobilization -Anti-inflammatory drugs -Trauma -Infection -Normal component of aging

true or false: Loss of PG matrix may be reversible dependent upon degree & duration

true

what are the early stage of development of OA?

-Fraying of collagen bundles in superficial layer -Rapid progression once fraying has begun b/c of fiber orientation within tissue

describe tissue degeneration in chondromalacia?

-Degeneration appears to begin in layers 3 & 4 -Early visualization of pathology is difficut

what should the intensity be in order to facilitate AC growth?

-Use pain, edema, effusion as a guide -Full body weight loading may be excessive

what should the duration and/or frequency be to facilitate AC growth?

-High reps (100-1000's) cyclical loading

what should the mode be to facilitate AC growth?

-Attempt to mimic function loading characteristics -May consider minimizing combinations of shear & compression

what is the gross function of bone?

-Protection for internal function -Rigid levers for attachment of muscles to allow motion -Harbors hemopoietic tissue for production of blood cells -Serves as a reservoir for calcium, phosphate, & other ions

what are the key features of bone structures?

-Highly vascular -Innervated -Dynamic CT -Capable of repair & remodeling

what is an osteocyte?

mature cells

what is an osteoblasts?

young cells (growth)

what is an osteoclast?

phagocytic

what is the relationship of osteoblasts & osteoclasts during; aging, disuse, healing & exercise?

-Aging : increase clastic (old) increase blastic (young) -Disuse: more absorption -Healing: clastic balance w/ blastic -Exercise: lay more bone down less clastic

what happens when effective applied load is decreased?

-Bone deposition decreases -Disuse atrophy

what may you see during casting & NWB status?

-Following 8 wks of immobilization -May see 3 fold decrease in load to failure, stiffness, & energy storing capacity

what does plates/screws implanted do?

-Reduce stress at fracture site may reduce/slow healing to normal strength -Fixation site strength may increase

which is stiffer & has a steeper slope of stress/strain curve?

cortical/compact bone

what is cancellous/ Trabecular bones porous structure allow?

-Great capacity for energy storage

when is bone more brittle?

-With age -More brittle w/ increasing velocity of loading (time dependent if things happen quickly)

what type of behavior does bone demonstrate & what does that mean?

-Anisotropic -Strength is greatest in direction in which loading is most common

what is the order of direction of loading from strongest to weakest?

-Compression -Longitudinal Tension -Oblique Tension -Transverse Loading

since cortical bone is stiffer than cancellous what does that mean?

-Cortical bone can withstand greater stress but less strain than cancellous bone

how much strain can cancellous bone sustain before failing compared to cortical bone?

-Cancellous bone (75%) -Cortical bone (2%)

why is bone deposition increased on the side of compression & absorption on side of tension?

(-) charge on side of compression & (+) charge on side of tension -Osteoblasts tend to migrate toward (-) electrode & osteoclasts migrate toward (+) electrode

what is the effect of muscle contraction on bone?

-Usually oppose antagonist or gravity to counterbalance bending -Acting independently create bending of bones -Create tension at tendon-bone junction -Create tuberoisties/trochanters developmentally -Pathological may create avulsion fx

what does constant compressive loading of bone produce?

-Increase endosteal diameter & increase in intracortical porosity

what does intermittent loading on bone produce?

-Increased bone mass

what occurs as a result of torsion on the bone?

spiral fractures

what is most sensitive to torsion forces?

-Epiphyseal plate -Under torsional load, newly formed bone will grow away from epiphysis in spiral fashion

what does a greater area of cross sectional area indicate?

-Stiffer & stronger bone

what does healing of a fx begin with?

large callus

what should the intensity be when treating bone?

-Loading within tissue structural tolerance -Move carefully into plastic zone -Pain free loading

what is the duration/frequency when treating bone?

-Many reps (cyclical loading)

what is the mode when treating bone?

attempt to mimic functional loading characteristic

what is the mechanical factors that strength depend?

-Rotary component of muscle force & length of MA

what is the physiological factors that strength depend on?

-Length of muscle -Velocity of contraction -Fiber orientation -Cross sectional area -Fiber type

when are type I muscles predominately called?

-Stability, postural, tonic muscles

when are type ii fibers predominately called?

-Mobility -Non-postural -Phasic muscles

what do epimysium, perimysium, & endomysium surround respectively?

-Epi (surround whole muscle) -Peri (surrounds the the fascicules) -Endo (surrounds the individual muscle cells)

what is the contractile element?

contractile proteins

what is the parallel elastic element?

peri, epi, & endomysium

what is series elastic element?

tendons

what occurs with an isometric contraction?

-Contractile element shortens -Series elastic element lengthens

when will the PEC stretch?

-Passively pulling on muscle beyond "rest" length & contribute to tension

what does muscle force have to do with cross sectional area/

-Fiber arrangement is key issue in determining cross sectional area -Muscle force varies with cross sectional area of the muscle

what ages does cross sectional area increase?

0-20

when does cross sectional area decrease?

30+

what age does one have maximal strength?

20-30

is cross sectional area loss reversible?

yes, and can be minimized

when does max shortening speed occurs?

-No resistance to shortening -No tension is developed in muscles b/c no resistance

during concentric what is the relationship b/w shortening speed & tension?

as shortening speed decreases , tension increase

why is there greater tension generated during isometrics than concentric?

speed is 0 so tension generated compared to concentric

what is the relationship b/w speed of lengthening & tension in eccentrics?

-As speed of lengthening increases, tension increase

what happens as the velocity of muscle contraction decreases & eventually become neg?

tension produced by muscle increase

when is isometric contraction good at strengthening?

-Great strengthening but only at joint angle that +/- 10 degrees

what is the issue with concentric contraction at strengthening?

-Dynamic but velocity-tension relationship often limits strengthening at higher velocites

Eccentric is great at strengthening but what is possible issues?

-Tissue damage (micro tears) due to potential for large muscle force production

what is the limitation of isotonic contraction?

-Dynamic contraction -Intensity limited by capability in weakest part if ROM (typically end range)

Tissue Flashcards

(84 cards)