Connective Tissue

Front 1

Functions of DCT

Back 1

o Provide and maintain framework for body structures
o Plays an important role in body defensive mechanisms
o Plays a role in intercellular exchange of oxygen, blood, water, gases, cells, and waste material
o Mechanical link between bones and provide mechanical support, stability and shock absorption in joints
o Plays an important role in transmitting muscle forces to skeletal system
o Plays an important role in distribution of forces throughout musculoskeletal system
o Function of immune system by modulating production, growth, differentiation and migration of various cells
o Allows communication between various body parts
 “matrix of life”

Front 2

CT basic components

Back 2

o Fibers
o Ground substance
o Cells

Front 3

• Vascularity

Back 3

o Tendons and ligaments have some degree
o Cartilage is avascular

Front 4

• Collagen types

Back 4

o Type 1 – bone, tendon, fascia
o Type 2 – cartilage
o Type 3 – vessels, smooth muscle, internal organs
o Type 4 – ground substance

Front 5

• Orientation types of CT

Back 5

o Dense regular
o Dense irregular

Front 6

• Two general types of cells in DCT

Back 6

o Resident cells
o Non-resident cells

Front 7

• Cellular components of DCT

Back 7

o Fibroblasts
o Myofibroblasts
o Adipose cells
o Plasma cells
o Mast cells
o Monocytes and microphages

Front 8

• Ground substance is made of three types of proteins

Back 8

o Proteoglycans
 GAGs attached to hyuronic acid
o Glycoproteins
 Holds cells together (ex. Fibronectin)
o Fiber proteins
 Elastin
 Collagen

Front 9

• Proteoglycan monomers

Back 9

o Aggrecan
 In cartilage
o Versican
 In blood vessels
o Decorin
 Type of GAG within collagen fiber

Front 10

• How does hyuronic acid increase pressure?

Back 10

o Since it is attached to a proteoglycan, it is hydrophilic, so loves water, and attracts water. Because of this, the tissue pressure is increased which enhances the ability of CT to resist compressive forces and pressure

Front 11

• Functions of glycoproteins:

Back 11

o Modulating cell attachments to other CT structures
o Controlling collagen fiber production: fibromodulin
o Stabilizing PG aggregates in cartilage: link protein
o Promoting tissue calcification: osteopontin

Front 12

• Collagen synthesis

Back 12

o Fibroblasts
o Golgi apparatus: sugars
o Rough ER: proteins
o Amino acids formed
o Procollagen
o Three together form a tropocollagen
o Called triple helix
o Hydrogen bonding
o Covalent bonding
o Form fibrils
o Form fibers
o Form fascicles

Front 13

• Stress

Back 13

o Amount of load per unit cross-sectional area

Front 14

• Strain

Back 14

o Proportional elongation of the CT that occurs under the stress application

Front 15

• Stress-Strain curve

Back 15

o Crimp: wavy CT
o Toe Region
 Don’t want to stretch beyond 4%
 The low force that can be applied to CT to stimulate fibroblasts
o Linear Region
 Increasing stress after crimp has been removed
o Plastic Region
 Gets to progressive failure
 Then region of major failure
• Area where it narrows where it wants to tear: necking
 Then complete rupture

Front 16

• Viscoelastic properties of DCT

Back 16

o Viscosity: resistance to motion
o Elasticity: ability to be stretched
o Viscoelasticity: resistance to elongation

Front 17

• What is occurring when the load on a tendon makes the tendon get longer?

Back 17

o Compliance

Front 18

• What is occurring when the load is removed and the tendon returns to its original shape?

Back 18

o Elasticity

Front 19

• What is creep?

Back 19

o Gradual lengthening of DCT with sustained load

Front 20

• Creep occurs at two levels:

Back 20

o Temporary elongation that shows recovery without injury with removing the load
o Permanent elongation is where creep progresses to denaturing and irreversible damage or rupture of CT

Front 21

• Effect of temperature on DCT

Back 21

o 37 degrees Celcius or less: full recovery after stretching
o 37-45 degrees Celcius recovery rate decreases
o 45 degrees Celcius or more cannot return to original length after being stretched
o 59-60 degrees Celcius has the CT undergoing shrinkage due to disruption of cross links between collagen molecules (called Melting Point)

Front 22

• How long is collagen’s half-life time?

Back 22

o 500 days

Front 23

• Factors that increase strength of scar tissue

Back 23

o Increasing collagen volume
o Increasing chemical bound stability
o Selective alignment and aggregation of collagen fibers along line of stress

Front 24

• Time factors governing scar tissue formation

Back 24

o Presence of CT cells
o Ability of CT cells to respond to mechanical stimuli

Front 25

• Window of opportunity to make changes in scar tissue:

Back 25

o 8-10 or 14 weeks

Front 26

• Factors involved in tissue stiffness

Back 26

o Loss of free motion due to decrease in GAG production
o Adaptive shortening

Front 27

• How would you stretch a tight connective tissue?

Back 27

o Low load, prolonged stretch

Front 28

• What is adaptive shortening?

Back 28

o When the tissue is held in a short length, formation of short collagen fibers will lead to contracture formation

Front 29

• What is adaptive lengthening?

Back 29

o When collagen production is stimulated by low load stretching, destruction of older short collagen fibers and production of longer collagen fibers leads to increased CT length and flexibility

Front 30

• What could happen if you have a prolonged stretch?

Back 30

o Decreased blood flow
o Ischemia
o Inflammation
o Myofibroblast activity
o Adaptive shortening and tissue tightness

Front 31

• To stimulate remodeling, how long would you use low load, prolonged stretching?

Back 31

o Less than a minute