Pathology Cheat Sheet
Close, Contract, or Complicate
Wound healing for NEET-PG: first vs second intention, granulation tissue, collagen types, keloid vs hypertrophic scar, vitamin C, and healing complications.
MedNext Academy | 3 min read
Close, Contract, or Complicate
Wound healing for NEET-PG: first vs second intention, granulation tissue, collagen types, keloid vs hypertrophic scar, vitamin C, and healing complications.
Wound healing by first and second intention and the local and systemic factors that impair or complicate repair.
High-yield lines
- Healing by first intention occurs in clean apposed wounds such as surgical incisions with minimal tissue loss and a thin scar.
- Healing by second intention occurs in large open wounds with tissue loss, abundant granulation tissue, and prominent wound contraction.
- Myofibroblasts expressing alpha-smooth muscle actin drive wound contraction and are activated by transforming growth factor beta.
- Granulation tissue is composed of new capillaries, proliferating fibroblasts, and loose extracellular matrix.
- Type III collagen is deposited first in a wound and is later replaced by stronger cross-linked type I collagen during remodelling.
- Wound tensile strength reaches only about 70 to 80 percent of normal by three months and never fully recovers.
- Vitamin C is required for hydroxylation of proline and lysine in collagen synthesis, so its deficiency causes scurvy and poor healing.
- Lysyl oxidase requires copper to cross-link collagen and give it tensile strength.
- A keloid is excess collagen that grows beyond the original wound margins, while a hypertrophic scar stays within them.
- Wound dehiscence is separation of a wound, most feared after abdominal surgery.
- Infection, poor perfusion, diabetes, malnutrition, corticosteroids, and foreign bodies delay wound healing.
- Contracture is exaggerated wound contraction that limits movement, especially over joints and after burns.
Mapped competency codes
- PA5.1
Continue into the full chapter
This summary maps to PA5-healing-and-repair.
Frequently Asked Questions
What is the difference between healing by first and second intention?
First intention heals a clean apposed wound with minimal granulation tissue and a fine scar, while second intention heals a large open wound with abundant granulation tissue and marked contraction.
How do keloid and hypertrophic scar differ?
A keloid grows beyond the boundaries of the original wound and rarely regresses, whereas a hypertrophic scar remains confined to the wound margins.
Why does vitamin C deficiency impair wound healing?
Vitamin C is a cofactor for prolyl and lysyl hydroxylase in collagen synthesis, so its deficiency produces weak collagen and poor healing in scurvy.
What is the maximum tensile strength a scar reaches?
About 70 to 80 percent of unwounded tissue strength, achieved by roughly three months, and it never returns fully to normal.
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