Chapter 9 Inflamation, Tissue Repair and Wound Healing

inflammation

response intended to:

• eliminate initial cause of cell injury

• remove damaged tissue

• generate new tissue

endothelial hyperpermeabillity

reaction of vascularized tissues to injury

inflammatory mediators

• tumor necrosis factor (alpha)

• vascular endothelial growth factors (VEGF)

• neutrophils

• movement of fluid within cells or interstitial fluid

-itis

inflammation

cardinal signs of inflammation

rubor, tumor, calor, dolor, functio laesa

rubor

redness

tumor

swelling

calor

heat

dolor

pain

functio laesa

loss of function

acute inflammation

short duration (minutes to days)

• exudation(secrete) of fluid and plasma, emigration of leukocytes(neutrophils) into tissues

what causes inflammation?

infections, trauma, immune reactions, physical agents, chemical agents, tissue necrosis from any cause

endothelial cells

barrier between circulating blood in vessels and surrounding tissues

what do endothelial cells produce?

antiplatelet and antithrombotic agents (maintains vessel patency)

vasodilators and vasoconstrictions regulate what?

blood flow

endothelial cells are involved in the formation of new blood vessels, this is called?

angiogenesis

platelets

• involved in primary hemostasis

• releases potent inflammatory mediators

  • increases vascular permeability

neutrophils

they are phagocytic leukocytes that arrive within 90 minutes

monocytes/ macrophages

phagocytic leukocyte that produce potent vasoactive mediators

vasoactive mediators

prostaglandins, leukotrienes, platelet activating factor, inflammatory cytokines

leukocytosis

increased white blood cells

bands

immature form of neutrophil

eosinophils

parasitic infection and allergic reactions

basophils

contains histamine

• binding of IgE triggers release

mast cells

degranulation releases histamine, TNF, IL-16

TNF (tumor necrosis factor)

hypotension, tachycardia associated with sepsis

vasodilation

induced by histamine and nitric oxide mediators

vascular phase

vasodilation, erythema (redness), warmth, edema (swelling)

edema

increased osmotic pressure causes fluid to move into tissues ad produce swelling

cellular stage

margination, chemotaxis, leukocyte activation and phagocytosis, etc.

margination

cytokines cause endothelial cells to express adhesion molecules (leukocyte accumulation to the endothelium)

chemotaxis

chemokines direct trafficking of leukocytes

leukocyte activation and phagocytosis

monocytes, neutrophils and tissue macrophages activated

phagocytosis

engulf and degrade bacterial and cellular debris

what do metabolic burst pathways do?

generates toxic oxygen and nitrogen products that requires oxygen

• this kills the microbe

histamine and prostaglandins have?

vasoactive and smooth muscle constricting properties

plasma proteases

activate complement system, clotting cascade, kinin system

chemotactic factors

chemokines

reactive molecules and cytokines are liberated from?

leukocytes

histamine

• found in mast and basophil cells

• involved IgE antibodies

what cells are first to be released?

mast and basophil cells

histamine causes what?

dilation of vessels, sneezing, runny nose, eye tearing, sinusitis, increased permeability

arachidonic acid metabolites

release leads to production of prostaglandins, induces inflammation, potentiate effects histamine

arachidonic acid metabolites promote?

platelet aggregation and vasoconstriction

platelet- activating factor

induces platelet aggregation and causes bronchospasm

plasma proteins

clotting, complement and kinin systems

clotting

endothelial adhesion, production of PAF

complement

increases vascular permeability, causes vasodilation, improves phagocytosis

kinin

releases bradykinin, increases permeability, contraction of smooth muscle

cytokines

TNF, IL-1 released in response to bacterial toxins, endotoxins, fever, lowers BP

nitric oxide

smooth muscle relaxation; compensatory mechanism that reduces inflammation

free radicals

released during phagocytic process

chronic inflammation

reaction that persists for a prolonged time (weeks to months) without resolution

etiologic agent examples

mycobacterium tuberculi (TB) and treponema pallidum (syphilis)

nonspecific inflammation

non-targeted response

granulomatous inflammation

chronic inflammation often causes a granuloma where there is massing of macrophages surrounded by lymphocytes (1-2 mm lesion)

tuberculosis

prototypical granulomatous chronic inflammatory disease

systemic manifestations of inflammation

acute-phase response, alterations in WBC count, fever, lymph node reaction

lymphadenitis

aka lymphadenopathy; the enlargement of lymph nodes caused by inflammatory processes

where do lymphocytes mature?

in the lymph node; become enlarged and tender during inflammatory process

tissue repair

response to injury in attempt to maintain normal body structure and function

regeneration

injured cells replaced with cells of the same type

replacement

leaves a permanent scar when replaced with connective tissue

body cells involved in tissue regeneration

labile, stable, permanent cells

labile

continue to divide and replicate throughout life, replacing cells that are continually being destroyed (epithelial cells)

what are cancer cells considered as?

labile cells because they are constantly dividing

stable

normally stop dividing when growth ceases; capable of regeneration when confronted with appropriate stimulus (liver and kidney cells)

permanent cells

cannot undergo mitotic division (nerve cells, cardiac muscle cells)

fibrous tissue repair

severe or persistent injury-repair cannot be accomplished with regeneration alone

• occurs by replacement with connective (granulation) tissue (scars)

granulation tissue

glistening red, moist connective tissue

• contains new capillaries (angiogenesis) and fibroblasts (fibrogenesis)

phases of wound healing

inflammatory phase, proliferative phase, wound contraction and remodeling phase

inflammatory phase

blood clot forms at time of injury

• migration of phagocytic WBC to wound site

• neutrophils arrive first to ingest and remove bacteria and cellular debris

• macrophages arrive 24 hours later (ingest cellular debris)

hemostasis

constriction, platelet aggregation, increased permeability

proliferative phase

building of new tissue to fill wound space

• fibroblasts and epithelialization

fibroblast

a connective tissue cell that synthesizes and secretes collagen and other substances needed for wound healing

what do fibroblasts produce?

growth factors that induce angiogenesis

epithelialization

final stage that forms new surface layer during the proliferative phase

remodeling phase

begins approx. 3 weeks (up to 12 months) after injury

• fibrous scar developed (increase in tensile strength and shrinks to become less visible)

• decreased vascularity

• collagen synthesis by fibroblasts

carefully sutured wounds have approx. ___% of strength of unwounded skin

70%

primary intention of wound healing

clean laceration (edges are well approximated)

• easily brought together, no missing tissue

secondary intention of wound healing

larger wounds that have greater loss of tissue and contamination

factors involved in wound healing

malnutrition, blood flow, oxygen delivery, impaired inflammatory and immune responses, infection, wound separation, foreign bodies, bite wounds

effects of age on wound healing

neonates, children, older adults

neonates and children

• greater capacity for repair

• may lack reserves needed to properly heal (electrolytes, temperature, rapid spread of infection)

• sufficient calories needed

neonates and children have immature?

immune systems

increased water content means?

epidermis at risk

older adults

• decreased in dermal thickness

• decline in collagen content

• loss of elasticity

• vulnerable to chronic wounds

inspect areas for redness after how many minutes in older adults?

30 minutes and perform position changes

less than 6 hours pressure

ulceration

braden scale

scale used to predict patient’s risk of developing pressure injures

• sensory perceptions, moisture, activity, mobility, nutrition, fraction shear