Wound Healing

CHAPTER 9
Wound Healing


Ramon Garza III


Test Taking Tips


• Questions tend to revolve around physiology of how wounds heal, that is, secondary intention, myofibroblasts, and which cells are involved in wound healing.


• The strength layer of bowel/skin is also commonly tested. One should also be familiar with which organs lack certain tissue layers such as the esophagus with no serosa and where the posterior rectus sheath starts/stops.


Name the 3 phases of wound healing:


Inflammation (1–6 days), proliferation (3 days–3 weeks), maturation (3 weeks–1 year)


Name several factors that can inhibit wound healing:


Diabetes, infection, ischemia, malnutrition, radiation, steroids, neoplasia, anemia


What are the optimal nutrition parameters?


Albumin >3 g/dL and prealbumin >16 mg/dL


What is primary wound closure (primary intention)?


Immediate closure of a wound with suture or staples


Most important factor in healing closed wounds by primary intention:


Tensile strength


What is the most important layer to close for strength in skin lacerations?


Dermis


How long does it take a surgical incision become “water tight”?


24 to 48 hours


What is secondary wound closure?


Leaving a wound open and allowing it to heal by granulation, contraction, and epithelialization over time


Most important factor in the healing of open wounds by secondary intention:


Epithelial integrity


What causes contraction in wounds healing by secondary intention?


Myofibroblasts


What is delayed primary closure?


Closing a wound several days (3–5 days) after incision


Rate of regeneration of a peripheral nerve:


1 mm/d or 1 in./mo


Rate of epithelialization:


1 to 2 mm/d


The strongest layer of the bowel:


Submucosa


The time period that a small bowel anastomosis is at its weakest:


3 to 5 days


Name the 2 major events in the process of epithelialization:


Migration and mitosis


Name the process by which keratinocytes pile up on top of each other at the leading edge of a migration and tumble forward over the top of the heap:


Epiboly


What cell is the most essential for wound healing?


Macrophage


This cell is responsible for the movement and contraction of wound edges:


Myofibroblast


Name the order of arrival of the different cells involved in wound healing:


Platelets (not a true cell)


Neutrophils (predominant cell type from day 0–2)


Macrophages (predominant cell type from day 3–4)


Fibroblasts (predominant cell type from day 5 and so on)


Lymphocytes


Platelet factor 4, β-thrombomodulin, PDGF, and TGF-β are contained in this type of platelet granule:


α granule


Adenosine, serotonin, and calcium are contained in this type of platelet granule:


Dense granule


Name the predominant cell during days 0 to 2 of wound healing:


Neutrophils


Name the predominant cell during days 3 to 4 of wound healing:


Macrophages


Name the predominant cell present after day 5 of wound healing?


Fibroblasts


When does the maturation phase usually begin?


~3 weeks after the injury


What is the maximal tensile strength that a wound can reach?


80% of original tissue strength


Time period for maximum collagen accumulation in a wound:


2 to 3 weeks (mostly type III, then gets converted to type I with maturation)


Image


Image


FIGURE 9-1.

Aug 13, 2019 | Posted by in ABDOMINAL MEDICINE | Comments Off on Wound Healing
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