733 Physiology of Skin Healing

first primary stage of healing

hemostasis

hemostasis details

• body stops the bleeding

• blood vessels vasoconstrict to reduce flow

• platelets rush to clot which forms a scab

• scab acts a natural bandage protecting against germs and dirt

second primary stage of healing

• WBC fight bacteria and clean dead tissue

• wound may look red, swollen, tender, painful

• some drainage may appear but decrease overtime

third primary stage of healing

proliferation

proliferation details

• days later, new tissue grows under scab

• wound shrinks as edges pull together

• pink or red skin signals new healthy tissue forming

• healing occurs from inside out

fourth primary stage of healing

maturation

maturation details

• can last weeks to years

• the scab fall off revealing new skin

• area may look pink or lighter at first

• over time, skin strengthens but scar remains

hemostasis clotting mechanism

• vasoconstriction

• platelet aggregation

• fibrin formation

hemostasis fibrin formation

activated by a cascade of clotting factors, fibrin strands weave across the platelet plug, stabilizing it into a firm clot. This serves as a temporary barrier, shilding the wound from external contaminants

inflammation stage- infection prevention

white blood cells predominantly neutrophils and bacteria engulf the bacteria and debris

inflammation stage- cytokine release

these chemical messengers facilitate communication between cells, signaling onset of the reparative stages

proliferation- collagen synthesis

fibroblasts produce collagen, a structural protein. This forms the basis of granulation tissue, a pinkish-red and moist tissue indicative of active repair

proliferation- wound contraction

myofibroblasts, specialized cells, draw the wound edges inward, reducing its size

proliferation- epithelialization

keratinocytes migrate across the wound, creating a new protective layer

proliferation- angiogenesis

new blood vessels sprout, ensuring a consistent supply of nutrients and oxygen to the regenerating tissue

maturation- collagen remodeling

the collagen fibers rearrange, aligning themselves with tension lines, thus enhancing tissue strength. However, even at its peak, the repaired tissue only achieves approximately 80% of the original skin’s tensile strength

scar formation

a by-product of the healing process, scars can range from flat and pale to raised and rigid. Their appearance is influenced by various factors, from genetic predispositions to the nature of the injury

positive clinical signs of healing

• decreased drainage

• color changes

• scab formation

• reduced pain and swelling