Orris
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Is the given answer incorrect?

The question asks which statement is true regarding wound contraction.
The app marked "It is the function of specialised fibroblasts that contain actin myofilaments" as correct (green border), and marked the user's answer "It may account for a maximum of 40% decrease in the size of wound" as incorrect (red border).
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wound contraction percentage decrease wound size myofibroblasts

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Now let me check what Schwartz's says about the percentage of wound size decrease, and also look at the other Schwartz block:
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I now have enough information to give a thorough answer. Here is the full analysis:

Yes - the marked answer has an error, and the app's correct answer also needs scrutiny

What the image shows

  • User selected (marked wrong - red border): "It may account for a maximum of 40% decrease in the size of wound"
  • App marked correct (green border): "It is the function of specialised fibroblasts that contain actin myofilaments"

Is the app's "correct" answer truly correct?

Partially - but the wording is imprecise.
Wound contraction is mediated by myofibroblasts, which are specialized fibroblasts containing actin filaments (specifically alpha-smooth muscle actin, or α-SMA, organized into stress fibers). So the answer is directionally correct.
However, the option says "actin myofilaments" - myofilaments are technically the individual protein filaments inside muscle cells. The more precise term used in surgery textbooks is actin stress fibers or α-smooth muscle actin. This is a minor semantic point, but the core concept is right.
As Schwartz's Principles of Surgery states: "The myofibroblast...possesses a cytoskeletal structure. Typically this cell contains α-smooth muscle actin in thick bundles called stress fibers, giving myofibroblasts contractile capability."

Is the user's answer (40%) wrong?

Yes - the figure is wrong, and wound contraction can actually reduce wound size by far more than 40%.
  • Wound contraction can reduce open wound area by up to 80-90% in wounds healing by secondary intention (not sutured wounds).
  • Research from Darby et al. found an 85.7% wound reduction in a rat model.
  • The commonly cited figure in surgery textbooks is that wound contraction can account for up to 40-80% of wound closure depending on location and wound type - but a "maximum of 40%" is too low and incorrect.
  • Schwartz's also notes: "Wounds contract at the rate of 0.75 mm to 1 mm daily," and the process continues for weeks.
The 40% figure is a significant underestimate. A "maximum of 40%" is simply not true - wound contraction routinely exceeds this in loose-skinned areas (e.g., perineum, axilla, neck).

Summary table

OptionVerdict
Primary process in sutured woundsFalse - sutured wounds close by primary intention; contraction is relevant to open/secondary intention wounds
Bacterial colonization slows contractionTrue in principle - infection delays all wound healing phases including contraction, but this is not the "best" single answer
Function of specialised fibroblasts (myofibroblasts) with actinTrue and best answer
Maximum 40% decrease in wound sizeFalse - wound contraction can reduce wound size by up to 80%+
The app's answer is correct. The user's chosen answer (40% maximum) is indeed wrong because wound contraction can account for up to 80-90% of wound area reduction in secondary-intention wounds - not a maximum of 40%.
Source: Schwartz's Principles of Surgery, 11th Edition - "Wound Contraction" section; wounds-uk.com review of fibroblast role in wound contraction (Darby et al., 1990 - 85.7% wound reduction)
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Is the answer correct

The question is about Zollinger-Ellison syndrome (ZES). The user selected "1, 2 and 3" (marked wrong - red border), and the app marked "1, 2 and 4" as correct (green border).
The key issue is whether statement 3 ("Beta islet cell tumour of pancreas") or statement 4 ("Diarrhoea present in up to 50% cases") is correct.
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Zollinger-Ellison syndrome gastrinoma cell type diarrhea percentage features

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The app's answer is incorrect. Here is a full breakdown:

What the image shows

  • User selected (marked wrong - red): "1, 2 and 3"
  • App marked correct (green): "1, 2 and 4"
The four statements:
  1. Aggressive and refractory peptic ulceration
  2. Unregulated gastrin release
  3. Beta islet cell tumour of pancreas
  4. Diarrhoea present in up to 50% cases

Analysis of each statement

Statement 1 - Aggressive and refractory peptic ulceration: TRUE ZES classically causes fulminating, refractory peptic ulceration in the stomach, duodenum, or atypical sites (e.g., jejunum). Over 90% of ZES patients have peptic ulcer disease.
Statement 2 - Unregulated gastrin release: TRUE The gastrinoma autonomously secretes gastrin without the normal feedback inhibition. This is the core pathophysiology of ZES.
Statement 3 - Beta islet cell tumour of pancreas: FALSE This is the critical error. ZES is caused by a non-beta (non-β) islet cell tumour - specifically a gastrinoma (a G-cell or delta/epsilon cell tumour). Beta cells produce insulin (causing insulinoma/hypoglycaemia), NOT gastrin. Bailey and Love's Surgery explicitly defines ZES as: "non-β islet cell tumours of the pancreas (gastrinoma)." So statement 3 is wrong to call it a beta cell tumour.
Statement 4 - Diarrhoea present in up to 50% cases: FALSE (it's much more common) This is where the app's answer is also wrong. Diarrhoea occurs in up to 73-75% of ZES patients, not just 50%. Multiple sources confirm this:
  • Gastroenterology Research: "Diarrhea (73%) are the most common clinical features of ZES"
  • PMC review: "up to 75% manifest diarrhea"
  • Bailey and Love's: describes diarrhoea as "another common symptom" without limiting it to 50%
So saying "diarrhoea in up to 50% cases" significantly underestimates the true frequency and is technically incorrect as well.

What the correct answer should be

The best answer is "1 and 2 only" if strict accuracy is applied, since:
  • Statement 3 is wrong (beta cell, not non-beta cell)
  • Statement 4 is wrong (diarrhoea occurs in ~73-75%, not just "up to 50%")
However, if the question is from an exam context where "up to 50%" is being used loosely to mean "at least 50% or more," then 1, 2, and 4 could be considered the intended answer - though even this is a poorly worded option because diarrhoea is actually closer to 73-75%.
The user's answer of "1, 2 and 3" is definitively wrong because statement 3 (beta cell tumour) is a classic exam trap - ZES involves non-beta (G-cell/gastrinoma) islet cell tumours, not beta cells.
The app's answer of "1, 2 and 4" is the intended correct answer, though statement 4 slightly underestimates the true diarrhoea prevalence. The most important take-home is that statement 3 is wrong - it is a non-β islet cell tumour, not a beta cell tumour.
Source: Bailey and Love's Short Practice of Surgery, 28th Ed. - "Zollinger-Ellison syndrome is...non-β islet cell tumours of the pancreas (gastrinoma)"
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