Connective Tissue Brainscape Flashcards
Major Components of Connective Tissue
• Fibers
o Collagen
o Elastin
• Ground substance with associated tissue fluid
• Cellular substances
o Fibroblast (osteoblasts in bone, chondrocytes in cartilage)
o Cells specific to each CT type
Type I Collagen
o Resistance to tension
• Ligaments, bone, dermis, fibrous cartilage, epimysium, perimysium, endomysium, fascia, joint capsule, meniscus, mature scar
Type II Collagen
o Resistance to intermittent pressure
• Loosely packed, no fibers, very thin fibrils such as hyaline and elastic cartilage, menisci
Type III Collagen
o Structured maintenance for organs
• Loosely packed, thin fibrils such as smooth muscle in CV and GI systems
Type IV Collagen
o Support and filtration
• Thin amorphous such as basement membrane
Collagen Arrangment Determins Tissue Type. True/False
TRUE
Collagen Arrangements
• Tendon o Closely packed and roughly parallel • Ligament o Not as parallel as a tendon but more organized than a capsule • Joint capsule o Loose weave of interlaced fibers
Collagen aligns purposefully according to direction of force or stress
- If no activity collagen does not align well
* Early movement allows for better alignment and motion
Purpose of Connective Tissue
- Support
- Strength
- Repair
- Mechanical connector between cells
Characteristics of Connective Tissue
- Abundant and diverse
- Provides tensile strength
- Weaker at tissue intersurface–>Strongest in the middle
- Vascularity is generally poor with the exception of bone
- Neural innervations are abundant (except in cartilage): muscle spindle, GTO
Elastin
Provides elastic properties by their unique cross linking
Inflammatory Phase
- The first phase of recovery after damage has occurred
- Initiates the healing process
- A rapid response to injury
Four Cardinal Signs of Inflammation
- Erythema
- Heat
- Edema
- Pain
Inflammatory Phase Progression
Vasoconstriction→Vasodilatation→Clot Formation→Phagocytosis
Proliferation Phase
- Second phase of healing
- Involves connective tissue (strengthen the site) and also epithelial cells (cover the wound)
- Epithelial cells form the covering of mucous and serous membranes and the epidermis of the skin
What Happens During Proliferation?
o Epithelialization
o Collagen Production
o Wound Contraction
o Neovascularization
Clot Formation
- Platelets are the first cells at the site of the injury.
* Platelets bind to the exposed collagen and release fibrin to stimulate clotting
Collagen Formation During Proliferation Phase
- Fibroblasts → procollagen → tropocollagen → collagen fibrils → collagen filaments → collagen fibers
- Tissue containing newly formed capillaries and myofibroblasts is called granulation tissue
Tissue Response to Loading
• Tensile loads are resisted primarily by collagen fibers
o These fibers respond by straightening from their resting position
o During the elastic phase, the collagen fibers respond in a linear fashion up to 4% elongation
o After the load, the tendon returns to its resting length
• If the tensile force elongates the tissue more than the 4%, plastic changes begin to occur
Viscoelastic Properties of Tissues
- A function of the ground substance
- A viscous material is resistant to flow, and an elastic material returns to the original state following deformation and after the force is removed
- The duration of the applied load and the rate at which the load is applied impact a tissue’s viscoelasticity
Creep
o When a load is applied for an extended period of time, the tissue elongates, resulting in permanent deformation. The amount of deformation depends on the amount of force and the rate at which the force is applied.
Relaxation
o When a tissue is pulled to a fixed length a certain force is required. As the tissue is held at this length, the amount of force necessary to maintain that length decreases
o How less force is required over a set amount of time
Effect of Creep and Relaxation Together
- Allow connective tissue to adapt to and function in a variety of loading conditions without being damaged
- Tissues pulled into tension lengthen and relax, which provides the rationale for stretching exercises to lengthen shortened soft tissue
Stress and Strain
• Stress
o The resistance of the intermolecular bonds to physical deformation when external loads are applied
• Strain
o The amount of displacement a material undergoes when a force is applied
Stress Strain Curve
Illustrates how as force is applied, connective tissue will deform, and in doing so will create an internal stress/tension
Factors Than Influence Connective Tissue
• An increase in temperature increases elasticity
• Force magnitude, (defined by magnitude, time, and direction), influence the performance of CT
o Low force applied slowly may cause tissue deformation
o High forces applied quickly may cause tissue failure
o Moderate force applied in a repetitive manner may cause tissue failure
o Injury may occur from any of the above conditions
Effect of Age on Connective Tissue
Gets tighter
o Lose hydration in tissue, decreasing mobility, increasing stickiness
Effect of Immobilization
o No significant remodeling going on due to the lack of stress.
o After 4 weeks of immobilization, muscle can lose up to 80% of the strength
o Collateral ligaments of knee can lose up to 40%
o Ground substance: dehydration, increase in intermolecular bonding, adhesion, bonding
Effect of Inflammation
o Chronic information – results in loss of movement in joint, collagen is in a irregular fashion, not strong
Strategies for prevention and reduction of contractures
Immobilize in lengthened position, introduce stress early, control inflammation, stretching, positioning
Key Points for Connective Tissue
• Slow stretch will allow ground substance to more easily deform (elongate)
• If your goal is to have strong CT, then create forces in the direction you want collagen laid down during remodeling
• The amount of force depends on the goal
o High forces applied quickly will result in tissue failure
o Low forces applied over time will gradually elongate
o Less force will be required to hold a given length over time, therefore increase force and change length
Other Things to Remember for CT
- Place CT in lengthened position during immobilization if possible
- Viscoelastic properties are influenced by temperature, force and time
- COLLAGEN ALLIGNS ITSELF IN THE DIRECTION OF THE FORCE APPLIED
Implications for Therapists
- It has been found that regular mobility of affected tissue helps maintain the lubrication and critical fiber distance
- Immobilization is associated with increased deposition of connective tissue along with loss of water in the tissue (dehydration) and an increase in intermolecular cross linking, further restricting the extensibility of the tissue
- What can we do to deter the negative affects that immobilization has on tissue/healing tissue
John Barnes Myofascial Release
- Not a lot of research to support this, evidence based supported
- Lots of reliance on patient preference and clinical experience, less on research
- It is unproven whether these techniques can break the collagen cross links and allow lengthening and realignment
