1. 4
Tissue: The Living Fabric: Part B
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2. Inflammatory Response
Triggered whenever body tissues injured
Prevents spread of damaging agents
Disposes of cell debris and pathogens
Alerts adaptive immune system
Sets the stage for repair
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3. Inflammatory Response
Cardinal signs of acute inflammation:
Redness
Heat
Swelling
Pain
(Sometimes 5. Impairment of function)
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4. Inflammatory Response
Begins with chemicals released into ECF by injured tissues, immune cells, blood proteins
Macrophages and epithelial cells of boundary tissues bear Toll-like receptors (TLRs)
11 types of TLRs recognize specific classes of infecting microbes
Activated TLRs trigger release of cytokines that promote inflammation
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5. Inflammatory Response
Inflammatory mediators
Histamine (from mast cells)
Kinins, prostaglandins (PGs), and complement
Dilate local arterioles (hyperemia)
Causes redness and heat of inflamed region
Make capillaries leaky
Many attract leukocytes to area
Some have inflammatory roles
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6. Inflammatory Response: Edema
 Capillary permeability  exudate to tissues
Fluid containing clotting factors and antibodies
Causes local swelling (edema)
Swelling pushes on nerve endings  pain
Pain also from bacterial toxins, prostaglandins, and kinins
Moves foreign material into lymphatic vessels
Delivers clotting proteins and complement
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7. Inflammatory Response
Clotting factors form fibrin mesh
Scaffold for repair
Isolates injured area so invaders cannot spread
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8. Clinical Applications
Benadryl (an antihistamine) – blocks receptor site (H1) for histamine receptors
Aspirin/Ibuprofen – inhibits formation/action of prostaglandins – reduces pain and fever
Cortisone cream – inhibits release/action of inflammatory chemicals
Naproxen – prevents formation of prostaglandins
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6/23/2012

9. Scab Epidermis Vein Blood clot in incised wound Inflammatory chemicals
Figure Tissue repair of a nonextensive skin wound: regeneration and fibrosis.
Slide 1
Scab
Epidermis
Vein
Blood clot in
incised wound
Inflammatory
chemicals
Migrating white
blood cell
Artery 1
Inflammation sets the stage:
• Severed blood vessels bleed.
• Inflammatory chemicals are released.
• Local blood vessels become more permeable, allowing white blood cells,
fluid, clotting proteins, and other plasma proteins to seep into the injured area.
• Clotting occurs; surface dries and forms a scab.
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10. Necessary when barriers are penetrated Cells must divide and migrate
Tissue Repair
Necessary when barriers are penetrated
Cells must divide and migrate
Occurs in two major ways
Regeneration
Same kind of tissue replaces destroyed tissue
Original function restored
Fibrosis
Connective tissue replaces destroyed tissue
Original function lost
6/23/2012
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11. Organization restores the blood supply:
Figure Tissue repair of a nonextensive skin wound: regeneration and fibrosis.
Slide 2
Regenerating
epithelium
Area of
granulation
tissue
ingrowth
Macrophage
Budding capillary
Fibroblast
Organization restores the blood supply:
• The clot is replaced by granulation tissue, which restores the vascular
supply.
• Fibroblasts produce collagen fibers that
bridge the gap.
• Macrophages phagocytize dead and dying cells and other debris.
• Surface epithelial cells multiply and migrate over the granulation tissue. 2
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12. Steps in Tissue Repair: Step 3
Regeneration and fibrosis
The scab detaches
Fibrous tissue matures; epithelium thickens and begins to resemble adjacent tissue
Results in a fully regenerated epithelium with underlying scar tissue
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13. Regeneration and fibrosis effect permanent repair:
Figure Tissue repair of a nonextensive skin wound: regeneration and fibrosis.
Slide 3
Regenerated
epithelium
Fibrosed area 3
Regeneration and fibrosis effect permanent repair:
• The fibrosed area matures and contracts; the epithelium thickens.
• A fully regenerated epithelium with an underlying area of scar tissue results.
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14. Regenerative Capacity in Different Tissues
Regenerate extremely well
Epithelial tissues, bone, areolar connective tissue, dense irregular connective tissue, blood-forming tissue
Moderate regenerating capacity
Smooth muscle and dense regular connective tissue
Virtually no functional regenerative capacity
Cardiac muscle and nervous tissue of brain and spinal cord
New research shows cell division does occur
Efforts underway to coax them to regenerate better
6/23/2012
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15. Aging Tissues
Normally function well through youth and middle age if adequate diet, circulation, and infrequent wounds and infections
Epithelia thin with increasing age so more easily breached
Tissue repair less efficient
Bone, muscle and nervous tissues begin to atrophy
DNA mutations possible  increased cancer risk
6/23/2012
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