Tissue Healing Flashcards
Connective Tissue section in PPT
Connective tissue
characterized by widely dispersed cells and a large volume of extracellular matrix
ex: bones, bursae, capsule, cartilage, ligaments, tendons, skin
Extracellular matrix
the part of connective tissues outside the cells, It comprises almost the entire volume of the tissue and determines the tissues function
- Fibrous/fibular(collagen fibers & elastin)
- Ground Substance/ interfibrillar
Cellular (extracellular matrix)
-Fibroblasts, fibrocytes
>Basic cell of most connective tissues
>Produce fibers of connective tissues and specialized cells
»_space;Chondroblast, tenoblast etc.
Collagen Fibers (IMPORTANT)
-Responsible for strength, stiffness and resistance to tensile forces
>Tensile strength similar to steel
Elastin (IMPORTANT)
- Flexibility and extensibility
- Found in tissues that need “give”
- Smaller portion of fibrous component
Intended to stretch? Or be stable?
Types 1 Collagen (important)
-90% of all collagen found in tendons, ligaments, joint capsules, synovium, bone
>Strongest type of collagen
Type 2 Collagen (important)
mainly in cartilage and intervertebral discs
Type 3 Collagen (important)
skin, muscle tendon sheaths
Interfibrillar/Ground Substance
Extracellular Matrix
-Fluid component of tissues; water and proteins Serves to: >Reduce friction between fibers >Form links between collagen fibers >Resists compressive forces >Helps dissipate tensile forces
What does the makeup and orientation of the tissue do/allow?
Gives it it’s strength and ability to withstand different forces
Mechanical Behavior of CT
- Dependent on proportions of collagen to elastin and structural orientation
- Collagen 5 times stronger than elastin
Increased collagen =
increased strength and decreased flexibility
Increased elastin =
greater flexibility and decreased strength
Parallel orientation of CT
-Resists tensile forces in that direction
>Tendon
Random orientation of CT
Withstand forces in a variety of directions
Mechanical properties of internal structures will dictate what?
how they respond to exercise, ROM, stretching and each tissue is different
- Forces
- Stress/Strain Curve
- Adaptation/Remodeling
What are the 3 types of mechanical stress?
Compressive
Tensile
Shear
Compressive Forces
-Two forces that act in line toward each other
> Force applied perpendicular to articulating surface
Weight bearing in LE’s or with muscle contractions
Therapeutically called “joint approximation”
Tensile Forces
-Two Forces applied in same line but in opposite directions
> Force applied perpendicular to the joint surface
Therapeutically called “distraction”, used in mobilization and ROM activities
“joint distraction”
Shear Forces
-Forces in opposite directions but not in line with each other
> Force is parallel to the joint surface
When load is applied there will be a combination of approximation and shear
If force applied at an angle and not perpendicular it will add shear
»_space;This can lead to injury
Shear additional info—-
shear–> One joint surface slides across the surface of another
–> Force is parallel to the joint surface –> can be destructive to joint surfaces because load quickly exceeds the ‘ultimate failure’ point
* significant because if compression force is applied at an angle that is not perpendicular - shear will be added
Shear typically a factor in tissue injury
Stress-Strain Curve
-Mechanical response of a selected internal structure to a deforming stress can be graphically represented
> Also referred to as load deformation curve
Demonstrates:
-Elasticity
-Plasticity
-Ultimate strength and stiffness of material
-The amount of energy the material can absorb before it fails
Stress= (Stress-Strain Curve)
magnitude of force or load being applied to internal structure
Strain = (Stress-Strain Curve)
amount of deformation that occurs to the structure in response to stress applied
Load = (Stress-Strain Curve)
forces applied to a structure
Elastic range (Stress-Strain Curve)
structure can return to original shape after deforming load
Yield point (Stress-Strain Curve)
point between elastic and plastic – where changes from one to the other and tissue can no longer immediately return to original length
Plastic range (Stress-Strain Curve)
the ability of a structure being loaded to permanently obtain a new length after load is removed
Failure point (Stress-Strain Curve)
tissue is unable to withstand anymore load without damage
Mechanical Failure (injury)[Stress-Strain Curve]
-Point where stress is too excessive and reaches a point at which internal structure can’t withstand it
> Fracture, laceration, sprain, strain
Example – stretch
>Load and duration sufficient to see changes in the plastic range to be effective
Remodeling (adaptations of bone)
- ongoing process throughout life
- To adjust to stresses presented in everyday life
Osteoblasts=Bone formation
Osteoclasts=Bone resorption
What is Wolff’s Law? (Important)
- the phenomenon that describes the remodeling of bone occurring in response to physical stress
- Bone will be deposited and align along lines of stress and reabsorbed if little or no stress is present
Bone Deposition- Wolff’s Law
important
-Developmentally if unable to weight bear will have difficulty maturing sufficiently
>Need weight bearing activities as we grow
-Recovery after fracture
>Bone developed through early
closed chain approximation activities
Bone resorption- Wolff’s Law
important
-Lack of stress can result in osteoporosis
> Reduction in bone mass sufficient enough to interfere with mechanical support of bone
*use this as support for pt to comply, need to be weight-bearing/Closed chained
