Tissue Mechanics Flashcards Preview

PT 506 Kinesiology > Tissue Mechanics > Flashcards

Flashcards in Tissue Mechanics Deck (62):
1

Loading Modes

Compression; Tension; Bending; Shear; Torsion; Combined Loading

2

Structure of connective tissues

Characterized by a wide dispersion of cells in the presence of a large ECM

3

Interfibrillar components

(Ground substance)

4

Fibrillar components

(fibrous)

5

Connective tissues are unique because...

Functions determined by ECM, unlike other tissues where cell behavior determines

6

Fibroblast

Basic cells of most connective tissue

7

Fibroblasts may become

Chondroblast
Osteoblast
Tenoblast

8

With maturation, fibroblasts are...

Fibrocytes
Chondrocytes
Oesteocytes
Tenocytes

9

Proteoglycans

Attached are one or more polysaccaride chains called glycosaminoglycans (GAGs)

10

Glycoproteins

Compound containing a carbohydrate covalently linked to protein

11

GAGs

Negatively charged, a concentration of GAGs creates a swelling pressure and H20 goes into ECF

12

Collagen fibers counteract GAGs by

resisting and containing the swelling via tensile stress and osmotic pressure

Tissue can resist compression

13

Tissues subjected to high compression forces have a ___ PG content

High

14

Tissues that resist tensile loads have a ____ PG content

Low

15

Collagen

Most abundant protein in the body
Strong as steel

16

Type I Collagen

predominantly in ligaments. tendons, menisci, and joint capsules

17

Type II Collagen

Predominantly in hyaline articular cartilage and nucleus pulposus of disk

18

Elastin

Properties allow the fibers to deform under force and return to original state

Generally less elastin in connective tissue

19

Connective tissue composition and structure

Sparsely vascularized, parallel fibers
Dense connective tissue in tendon and ligament

20

Type I collagen production

Fibroblasts make procollagen which is cleaved to produce type I collagen

21

Coiling of connective tissue

Polypeptide chain coiled in left handed helix
Three alphas chains are then coild in a right handed helix.

22

Cross links

Formed by GAG's between collagen molecules
Aid in strength

23

More elastin in _____ than ____

Ligaments; Tendons

24

Overload

Tissues increase their structural or functional capability in response to overloading

25

Specificity

Specific stimulus for adaptation elicits specific structural and functional changes in specific elements of tissues

26

Reversibility

Discontinueing training stimulus will result in loss of adaptive changes

27

SAID

Specific Adaptations to Imparted Demand

28

Elasticity

Property of a material to return to original form following removal of deforming load

29

Plasticity

Property of a material to deform permanently when loaded beyond its plastic range

30

Viscocity

Property of a material to resist loads that produce shear
Higher viscosity -----> Slower deformation

31

Elastic Materials

Energy is stored during loading and released during unloading
Loading/Unloading curves are the same

32

Visco-Elastic materials

Sensitive to rate of loading or deformation
Higher rates lead to more deformation

33

Creep

Load is suddenly applied then held constant
Continued deformation over time

34

Stress Relaxation

Deformation held constant
Force required to maintain deformation decreases over time

35

Cyclical Loading

Causes a shift of the load:elongation curve to the right
Shift decreases in magnitude with each repitition

36

Hysteresis

Energy loss

37

Viscoelastic behavior

Increased stiffness w/ increased strain rate

38

Tendon Loading

Tendon has 2x the tensile strength of muscle
Muscle rupture is more common than tendon rupture

39

Investing DCT

Paratenon: Outside
Epitenon: Synovial tissue only in high friction location
Endotenon: continuous with perimysium and periosteum

40

Sharpey's fibers

Link tendon to bone, go into the bone

41

Tendon Inflammatory phase

Cellular Reaction

42

Tendon Collagen Synthesis

Proliferation

43

Tendon Remodeling

Maturation

44

Immobilization in tendons

Reduces water content; PG Content; and strength. Tendon softens in 1-2 weeks

45

Early intermittent passive mobilization

CPN machine
Ultimate load increased
Reduced adhesions

46

Functions of Myotendinous Junction

Adhesion
Force transmission
Force mustnt exceed strength of interface & adhesion

47

Muscle tendon & bone-ll-bone failure

Pre-epiphyseal closure - failure at epiphysis
Post-epiphyseal closure - failure at mtj
Avulsion less common than mid substance in adults

48

Stretching Connective Tissues

Mode
Intensity
Frequency
Duration

49

Loading effect on length of Peri-articular DCT

low load of 5-40 minutes
Mobilization doesnt effect length, but can enhance ROM

50

Loading effect on muscle length

30 Seconds minumum continuous duration (maintain end range)

51

Strength Tissue Training

3-5 sets
6-12 Reps

52

Muscular Endurance Training

3-5 sets
20-30 Reps

53

Tendon Training

3-5 sets
30-40 Reps

54

Ligament Training

1000s of reps

55

Cartilage Training

Hours of reps

56

Articular Cartilage Physiological Features

Avascular, aneural, low metabolism
Withstands loading, distributes load, low friction

57

Zone 1 of articular cartilage

Nearly horizontal fiber direction resist shear

58

Zone 2 of articular cartilage

Slightly diagonal fiber direction to resist some shear, some compression

59

Zone 3 of articular cartilage

More vertical, resist more compression

60

Zone 4 of articular cartilage

Vertical fiber direction resists compression

61

Chondrocytes

Make & secrete matrix
Electrical activity elicits a synthesis response

62

Unique property of AC

Fluid component. Water content decreases and PG content increases with depth of tissue