265 Mechanical loading and inflamitory response

Compression- Flattening by forces squeezing together

Tension -Stretching by forces pulling apart

Sheer- force that is parallel to the surface or cross section of the body

Torsion- rotational force causing one end to twist

Bending- 3 points of force- being shaped into a curve or ankle. mostly happens in bones

Stress

load, measurable force placed on a tissue during: Compression

• Tension

• Sheer

• Torsion

• Bending

Strain

deformation

• how much does the tissue change shape?

  • compress

  • stretch

  • displacement

  • twist

  • bend 

5 syptoms of injury

1. Pain

2. Swelling

3. Redness

4. Warmth

5. Loss of Function

First Stage of Healing

inflammatory response, 0 to 3-5+ days.

Inflammatory Response job

stop the bleeding & prevent infection.

How does the inflammatory response phase work?

1. ↑Blood flow & signal more flow

 

2. Wall off & clean up

 

1. ↑Blood flow & signal more flow

• Brief vasoconstriction followed by vasodilation

inflammatory response signal more flow

Release of chemical mediators

• Histamine -  ↑ vasodilation & cell permeability = more exudate (fluid)

2. Wall off & clean up of inflammatory response

• Leukotaxin causes margination (leukocytes line up on cell wall)

• Leukocytes & platelets bind to 'sticky' fibrin on damaged cell wall to 'wall off' the injury (fibrin clot)

The job of leukocytes and necrosin

• Leukocytes & Necrosin clean up debris and fight infection (phagocytic activity).

Second Stage of Healing

proliferation or fibroblastic repair 6-8 weeks days

fibroblastic repair job

Big Picture: make a scar

1.  ↑ Vascularization

2.  Granulation tissue formation

3.  Extracellular matrix of collagen, elastin, & ground substance

(fibro repair) 1. ↑ Vascularization

Endothelial capillary growth delivers nutirents.

(fibro repair) 2. Granulation tissue formation

• Delicate tissue | Fills gap

• Fibroblasts arrange parallel to capillaries

• Composed of capilaries, collagen & fibroblasts

(fibro repair)- 3. Extracellular matrix of collagen, elastin, & ground substance

• Collagen and Elastin are laid in a random fashion

• ↑ scar tensile strength

• ↑ collagen signals maturation phase

third Stage of Healing:

maturation- remodeling 

6 months - 2 years

maturation phase

Big Picture: make scar stronger

 

1.  Re-aligns (remodels) collagen fibers to increase tensile strength along the lines of stress and strain.

If tissue goes to the plastic zone

it will not return to normal shape quickly

tissue that remains in the elastic zone

will return to normal shape fast

Bones are more likely to

bend