Inflammation & the Healing Process Flashcards
Primary Injury
- Macrotrauma and Microtrauma
- Ultrastructural changes
- Swelling
Macrotrauma
large injury that results in failure of musculoskeletal structures
Microtruama
Overuse, cyclic loading, friction injuries. Small stresses cause injury overtime
Primary injury causes
- Physical agents ( force, burns, radiation)
- Metabolic processes (ischemia, hypoxia)
- Biological agents (bacteria, parasites)
- Chemical agents (acids, chemicals)
Secondary Injury
Cells that were not injured in the primary injury become injured because of this process
Secondary injury: Enzymatic injury
Lysosomal mechanism
- cell membrane destroyed and everything within it released including lysosomes which eat tissue
Secondary injury: metabolic injury
- Ischemia > hypoxia > inadequate fuel > inadequate waste removal
- Membrane permeability mechanism
- Mitochondrial mechanism
Inflammation
A coordinated, complex, and dynamic series of events that develops as a result of trauma or injury to vascularized tissue
Cardinal signs of Inflammation
- Heat (calor)
- Redness (rubor)
- Swelling (tumor)
- Pain (dolor)
- Loss of function ( functio laesa)
Cause of heat
increased vascularity
Cause of Redness
Increased Vascularity
Cause of Swelling
blockage of lymphatic drainage
Cause of pain
Physical pressure and/or chemical irritation of pain sensitive structures
Cause of loss of function
Pain and swelling
Phases of tissue injury and repair
- Hemostasis (immediate sec/min)
- Inflammatory stage (days 1-6)
- Proliferation stage (Days 3-10)
- Maturation Stage ( day 9 on)
Hemostasis phase vascular response
Vasoconstriction in injured vessels
Hemostasis phase hemostatic response
Controls blood loss
Inflammatory Phase characteristics
- Vascular changes
- exudate of cells and chemicals
- Clot formation
- Phagocytosis
- Neutralization of irritants
- Early fibroblastic activity
Inflammatory phase Clinical Signs
- Inflammation
- Pain before resistence
- Tender to Palpation
Inflammatory phase impairments
- Pain
- Edema
- Muscle Spasm
- reduced AROM/PROM
- Joint effusion
- Decreased use of associated areas
Inflammatory phase vascular response
- Dilation of non-injured vessels in area of trauma
- mediated by histamine, hageman factor, bradykinin, prostaglandins, and complement fractions
- allows leukocytes into injured area -eat up junk
- neutrophils migrate to injured area
- line the endothelium of vessels (migration)
- lay down in layers (pavementing), mediated by fibronectin
- squeeze through vessel walls (diapedesis)
- move from inside to outside blood vessl (extravasation)
- migrate from blood vessels to parivascular tissue (emingration)
- **Allows protein-rich fluid to escape into tissues
Swelling
accumulation of fluid within extravascular space and interstitial tissues
Hemmorrhaging
Due to damaged vessels
- Blood accumulated in tissue= hematoma
- Blood accumulated in joint= hemarthrosis
Edema
Fluid portion of blood in tissues
- due to changes in fluid dynamics
- proteins attract water- draws plasma out of vascular tissue
Capillary filtration Pressure equation
CFP= (CHP + TOP) - (THP + COP)
CHP
Capillary hydrostatic pressure
TOP
Tissue osmotic pressure
THP
Tissue hydrostatic pressure
COP
Capillary osmotic pressure
hydrostatic pressure
pressure exerted by a column of water (pushes water)
osmotic pressure
pressure resulting from attraction of fluid by free proteins (pulls water)
Changes in Capillary filtration pressure (CFP) after injury
- TOP increases
- Pulls fluid into tissues
- edema and swelling results
- but initial swelling after injury from hemorrhaging
Erythrocyte response to injury- inflammatory stage
play minor role in inflammatory process
Leukocyte response to injury- inflammatory stage
- clear injured area of debris and microorganisms
- set the stage for tissue repair
Cellular response: first 24 hours
Polymorphonuclear leukocytes
- Neutrophils
- Basophils
- Eosinophils
Neutrophils
- pagocytosis
- release enzymes (protease) & collagenolytic enzymes (collagenases)
Basophils
- release histamine
- contribute to increased vascular permeability
- apply cold= decrease amt of histamine= vasoconstriction
Eosinophils
Phagocytosis
Cellular response: first 24-48 hrs
Mononuclear leukocytes
- Monocytes
- Lymphocytes
Monocytes
- converted into macrophages
- collagenase
- fibronectin
- hydrogen peroxide, ascorbic acid, lactic acid
- Most effective in oxygen rich environment in tissue
Lymphocytes
Supply antibodies
- mediate immune response
Immune response to injury
- B lymphocytes
- T lymphocytes
- Activation of complement system
immune response: B lymphocytes
release antibodies into bloodstream
immune response: T lymphocytes
Assist B cells in regulation of cloning
immune response: activation of complement system
Series of enzymatic plasma proteins
- increased vascular permeability
- stimulate phagocytosis
- act as chemotactic stimuli for leukocytes
Metabolic response to injury
Hypoxia: cell deprived of oxygen (lack of blood supply)
- switches from aerobic to anaerobic metabolism-glycolysis-glucose conversion to lactic acid
-Decreased ATP production
-Decreased cell membrane function
*Na+ pump slows or stops> [Na+] inside cell increases>
»_space; increased cellular H20> cell swells> burst or die
- increased cellular acidosis
Proliferation Phase (days 3-20)
- Second phase
- involves both epithelial cells and CT
- Purpose is to cover the wound and impart strength to injured area
Proliferation phase characteristics
- Removal of noxious stimuli
- Growth of capillary beds into area
- collagen formation
- granulation tissue formation
- very fragile
- easily injured tissue
Proliferation clinical signs
- decreasing edema
- pain felt with tissue resistance
- Tender to palpation but less than when acute
Proliferation Phase impairments
- Pain at end ROM
- decreasing soft tissue edema
- decreasing joint effusion
- developing soft tissue, muscle, & joint contractures
- developing muscle weakness
- decreased functional use of the part or associated areas
Epithelialization
- Provides protective barrier to seal wound
- uninjured epithelial>migrate over injured area> cover wound surface> close defect
- stimulus> loss of contact inhabition
- stop when migrating cells come in contact with other cells (contact inhabition)
Collagen Production
- Fibroblasts produce collagen
- Fibroblast growth occurs in CT (fibroplasia)
- Fibroblasts> procollagen> tropocollagen> collagen fibrils> collagen filaments> collagen fibers
- granulation tissue
- infection, edema, excessive stress can cause additional inflammation and collagen production> can limit function
granulation tissue
composed of capillaries, fibroblasts, and myofibroblasts
Initially what type of collagen is formed?
Type III collagen
What do collagen cross links do?
Allow for increased tensile strength
- allow early, controlled movement
- proper growth and alignment develops if tensile loaded in the line of normal stress to that tissue
By day 12 of collagen production…
type III collagen starts being replaced by more mature and stronger type I collagen
-Amt of collagen in wound and tensile strength linearly related to O2 available to healing tissue
Wound contraction
- Final mechanism for tissue repair
- pulls edges of wound together
- begins approx 5 days post injury
- myofibroblasts> pull epithelial layer inward
- rate proportional to # of myofibroblasts
- if uncontrolled can lead to contractures
Wound closure: muscle and skin
5-8 days