Week 1: Inflammation Response/ Wound Repair Flashcards
What is the goal of wound healing?
To restore the structural and functional integrity of the injured tissue
What are the outcomes of wound healing?
Regeneration and resolution
Repair
What is regeneration and resolution?
Returns tissue back to original structure and function
What is repair?
Returns tissue structure but not function
What are some tissues that undergo regeneration and resolution when damaged?
Corneal epithelium
Bone
Superficial skin
What are some tissues that repair when wounded?
Heart, brain, retina
What does wound healing begin with?
Acute inflammation
What are the phases of wound healing?
Inflammation phase
Proliferative Phase
Maturation Phase
When does the inflammatory phase occur?
Day 2-5
When does the proliferative phase occur?
Day 5 to week 3
When does the maturation phase occur?
Week 3 to year 2
What happens in the inflammatory phase?
- Acute inflammatories send phagocytic cells and clotting factors to the damaged site:
- blood clots, bleeding stops
- destroys foreign agents
- Constriction of blood supply
- formation of scab
- Debridement: removing clots, microorganisms, red blood cells, and dead tissue cells. Prepares for tissue growth. Phagocytosis by macrophages.
- Edema dissipates after debridement.
What happens in the proliferation phase?
- Granulation tissue develops (vascularized connective tissue full of macrophages)
- Angioblast proliferation (blood vessel growth)
- Fibroblast proliferation (collagen and extracellular matrix synthesis, also precursor for scar)
- Contraction ( Myofibroblasts gradually close wound)
- Epithelialization (Matrix Metalloproteinases remodel new collagen in wound. Cell differentiation occur when edges of wound meet.)
What happens during the maturation phase?
Continued cellular differentiation (epithelium)
Scar remodeling, trying to make the scar smaller
Collagen becomes more organized
Granulation tissue becomes connective tissue
Can last up to 2 years.
Local factors that affect wound healing
Size Infection Location Mechanical factors Foreign bodies
Leading cause of delayed wound healing
Infection
Systemic factors affecting wound healing
Nutrition:
Protein- decreased collagen production
Vitamin C- inhibits collagen synthesis
Metabolic Diseases - Diabetes Type 2; any other disease that messes up processes
Vascularization disease - Atherosclerosis, arteriosclerosis, or varicose veins. Impairs blood flow
Hormones - Cortisol; specifically endogenous glucocorticoids (STRESS) are anti-inflammatory and slow healing
4 examples of dysfunctional wound healing
Dehiscence
Ulceration
Keloid
Contracture
Most common cause of dehiscence
Infection
What is dehiscence? What can cause it?
Dysfunctional wound healing. The wound pulls apart at the suture line. Deficient scar formation -excessive strain -obesity -infection
What can cause an ulceration?
Inaquadate blood supply
Infection
Mechanical factors (bed sore)
What is a keloid? Who has a higher incidence?
Excessive fibroblast growth. Dont have an “off switch” and will produce excess collagen matrix.
- African Americans get them more often.
- Doctors need to know if the patient has keloids for procedure purposes.
What is a contracture? Does it have primary or secondary wound healing intentions?
Dysfuctional wound healing that has increased myofibril activity.
Burns increase the myofibril activity. It has secondary intention.
Burn victim would have this
Injured tissues are repaired by regeneration of ___________ or by ___________ repair in which scar tissue is substituted for the ____________ of the injured tissue.
parenchymal cells; connective tissue; parenchymal cells
True or false:
Scar tissue repairs the structure with functioning parenchymal cells.
False; it does not repair with functioning parenchymal cells.
Repair is the replacement of destroyed tissue with _______
Scar tissue
What is a scar primarily made of?
Collagen.
What is primary intention wound healing? What happens?
Limited injury wound healing mostly associated with the epidermis.
Would be a clean cut like a paper cut or surgical incision. Edges are in opposition.
Able to close edges of the wound which provides greatest chance for regeneration.
Provides minimal tissue loss.
Fibrin clot from coagulation system and trapped platelets.
Clot dissolves as healing progresses. Forms granulation tissue
What is granulation tissue?
New tissue after injury that contains blood vessels. Activates angioblasts that create blood vessels to supply to injured area. Gradually replaces blood clot at injured site.
What is secondary intention wound healing?
Wounds that require a great deal more tissue replacement. Open wound/ tissue loss
Almost always getting repair healing.
More likely to have scar.
Only regain 80% of original tensile strength.
How would skin heal faster if there is a scab?
Keep the scab moist. This keeps the fibrin clot moist and able to move easier. Less likely to scar
What directly stimulates fibroblasts?
Macrophages stimulates fibroblast proliferation. Through transforming growth factor B into cytokines.
What do matrix metalloproteinase (MMP) do?
They move through collagen to dissolve it where necessary to get where it needs to go.
What part of the eye has regeneration?
Corneal epithelium
What part of the eye undergoes repair?
Corneal Stroma, scar not clear.
Retina. Looses clarity from inflammation
Describe wound healing abilities change with a young baby?
Inefficient chemotaxis: phagocytic cells don’t move well (and neither do neonates!)
Complement deficiency
Antimicrobial peptide deficiency
Limited biochemical barriers
Describe wound healing abilities change with old age?
Reduced innate immune response:
- Fewer cellular mediators
- Diminished chemotaxis
- Decreased phagocytotic activity
Impaired inflammation:
- Impaired metabolism and tissue perfusion
- Medication effects
Loss of regenerative ability:
- Thinning of skin
- Loss of subQ fat
Describe pyogenic granuloma
Benign, vascular lesion
Not infectious
Not chronic
Associated with trauma or a mild irritant
More common in young
Typically removed for comfort and cosmesis
What type of cell gets to an injury the quickest?
Neutrophil
