# Wound Healing

> Wound healing notes for MBBS Pathology — phases, primary vs secondary intention, complications and exam-focused revision points.

- Canonical URL: https://prepelephant.com/topics/mbbs/pathology/wound-healing
- Exam / course: MBBS · Subject: Pathology
- Publisher: PrepElephant (https://prepelephant.com) — Prepared and reviewed by the PrepElephant Academic Review Team
- First published: 2026-10-02
- Last updated: 2026-10-02
- How to cite: "Wound Healing", PrepElephant, https://prepelephant.com/topics/mbbs/pathology/wound-healing

## Direct answer

Wound healing is the orchestrated replacement of damaged tissue by regeneration and repair, passing through haemostasis, inflammation, proliferation (granulation tissue formation) and collagen remodelling. Healing by first intention occurs in clean, closely apposed wounds such as surgical incisions; healing by second intention occurs in open or infected wounds, which fill with granulation tissue, contract and leave a larger scar.

## What you must remember

- Haemostasis comes first: platelets form the plug and release PDGF and TGF-beta, which launch the repair sequence.
- Inflammatory phase (roughly days one to three): neutrophils and then macrophages clear debris; macrophages are the master coordinators, providing debridement plus the growth factors that recruit fibroblasts and vessels.
- Proliferative phase: granulation tissue — new capillaries, fibroblasts and myofibroblasts in a loose extracellular matrix — fills the defect, collagen is laid down mainly as type III, and the epithelium creeps across the surface.
- Remodelling over months replaces type III collagen with stronger type I; a healed wound never regains full strength, reaching at most about seventy to eighty per cent of unwound skin.
- Secondary intention differs from primary in requiring abundant granulation tissue, wound contraction by myofibroblasts and a larger final scar; contraction is the main reason open wounds close.
- Healing is delayed by infection, foreign bodies, ischaemia, diabetes, malnutrition, glucocorticoids and irradiation; it needs adequate oxygen, protein, vitamin C for collagen hydroxylation and zinc.
- Complications: hypertrophic scars (raised, confined within the wound, tend to regress), keloids (extend beyond the wound edge, recur after excision, commoner in dark-skinned people), dehiscence, incisional hernia, contractures across joints and excessive granulation ("proud flesh").

## Common confusion

Keloid versus hypertrophic scar is the classical exam trap. A keloid outgrows the original wound boundary, contains disordered excess collagen, recurs after excision and has a familial tendency; a hypertrophic scar stays within the wound margins and usually flattens with time. Both are benign overgrowths of scar tissue — the boundary, not the raised appearance, separates them.

## Exam-focused takeaway

For theory, describe the four phases with their dominant cells and mediators, contrast primary with secondary intention, and list promoting and delaying factors with complications. Viva questions cover the composition of granulation tissue, the role of vitamin C, and why wounds never regain full tensile strength. MCQs test type III versus type I collagen timing, myofibroblast-driven contraction, the keloid-hypertrophic distinction and the central role of macrophages.

## Frequently asked questions

### What is granulation tissue?

Pink, soft, granular tissue composed of new capillaries, proliferating fibroblasts and myofibroblasts in a loose matrix — the histological hallmark of the proliferative phase.

### How do keloids differ from hypertrophic scars?

Keloids extend beyond the original wound margins and recur after removal; hypertrophic scars remain within the margins and often regress spontaneously.

### Why is vitamin C essential for wound healing?

It is the cofactor for hydroxylation of proline and lysine in collagen; without it, collagen is unstable and wounds break down, as in scurvy.

### Why do open wounds contract?

Myofibroblasts containing smooth muscle actin pull the wound edges together, greatly reducing the tissue deficit that must be filled.

### Does a healed wound ever regain normal strength?

No — remodelling restores at most about seventy to eighty per cent of the original tensile strength.