PMI03-2024 Wound Healing Flashcards
what is regeneration?
The replacement of lost or damaged tissue by that of a similar type derived from the proliferation of the surrounding undamaged cells
Which organ can regenerate itself?
liver
What is repair?
Replacement of lost of damaged tissue by granulation tissue which later matures into fibrous scar tissue
What are the two types of healing?
Primary intention
secondary intention
What are the 4 stages of healing?
Haemostasis
Inflammation
Proliferation
Remodelling
What is the wound like in primary intention?
The wound edges are in close apposition
What is the wound like in secondary intention?
Wound is more extensive and the wound edges are widely separated
When will primary intention occur?
Occurs in wounds with dermal edges and these edges are brought together so that they are adjacent with each other
When the wound is precise with minimal disturbance to local tissue and epithelial basement membrane
What is the difference between primary and secondary intention?
Primary is faster and produces less scarring
When does secondary intention occur?
Wound is more extensive and wound edges are not in close proximity
What direction does the wound heal in secondary intention?
From the bottom upwards
What covers the wound in secondary intention?
Granulation tissue
What occurs during haemostasis?
Platelets and cytokines form a haematoma and cause vasoconstriction
This limits blood loss from the affected area
Platelet plug formation and fibrin clot formation are the end results of this phase
How does the closer the proximity of the wound edges affect the clot?
The closer the proximity of the wound edges, the easier the formation of a clot and prevent infection by forming a scab
What factors affect the haemostasis stage?
Aspirin
Warfarin
Factor VIII deficiency
What occurs during inflammation?
Removes any cell debris and pathogens
What occurs during proliferation?
Proliferation of fibroblasts and endothelial cells lead to the formation of granulation tissue
New blood vessels migrate from the wound edges
The small blood vessels are accompanied by fibroblasts and inflammatory cells
The production of collagen in the ECM by fibroblasts allows for the closure of the wound after one week
What type of tissue is granulation tissue?
Loose cellular connective tissue
What occurs during remodelling?
Decreased cellularity and decreased vascularity
Remodelling of collagen matrix as there is collagen cross linking
What is the end result of primary intention healing?
Complete return to function, with minimal scarring and loss of appendages
What occurs during re-epithelialisation?
Proliferation of the basal epithelial cells adjacent to the wound
Basal cells then migrate to across the wound bed under the fibrin scab to restore the epithelial community
Epithelial cells differentiate and stratified squamous structures reform
When does haemostasis and platelet plug and clot formation occur?
1 hour after injury
When does inflammation occur?
48 hours after injury
When does granulation tissue form?
2-5 days after injury
When does maturation, remodelling and wound contraction occur?
More than 5 days after injury
When does re-epithelialisation occur?
1-3 days after injury
What local factors affect wound healing?
Type, size and location of the wound Local blood supply Infection Foreign material/ contamination Radiation damage
What systemic factor affect wound healing?
Increasing age
Obesity
Nutritional status (vitamin C deficiency)
Medical conditions (diabetes, CV disease)
What are complications of wound healing?
Wound dehiscence- wound rupturing following surgical suturing
Contractures- the pattern of wound contraction can cause issues
Keloid/ hypertrophic scar formation following excessive collagen production
Weak scars
Pigmentation
What is a keloid scar?
Sharpely elevated progressively enlarging scar
Due to the formation of excess collagen in the dermis during connective tissue repair
May spread beyond the margins of the original wound
Do keloid and hypertrophic scaring affect the face?
Seen on face but does not affect the oral mucosa
What is hypertrophic scarring?
Similar to keloid but does not spread beyond wound margins
