An adult old man gets burn injury to his hands. Over a few weeks, the burned skin heals without the need for skin grafting. The most critical factor responsible for the rapid healing in this case is –
**Core Concept**
The question tests the understanding of the role of collagen synthesis in wound healing, particularly in the context of burn injuries. Collagen is a crucial protein that provides strength and structure to the skin, and its synthesis is a critical factor in wound closure.
**Why the Correct Answer is Right**
In the case of burn injuries, the initial phase of wound healing involves the formation of a temporary wound covering, which eventually gives way to the granulation tissue. The granulation tissue is rich in collagen, which is synthesized by fibroblasts. The rapid healing of the burn injury in this case can be attributed to the increased collagen synthesis, which provides the necessary strength and structure to the skin. This is often seen in young adults and children, who have a higher rate of collagen synthesis compared to older adults.
**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because the rate of collagen synthesis decreases with age, making it an unlikely factor for rapid healing in an older adult.
**Option B:** This option is incorrect because the rate of wound contraction, which is mediated by myofibroblasts, is not the primary factor responsible for the rapid healing of burn injuries.
**Option C:** This option is incorrect because the role of angiogenesis, or the formation of new blood vessels, is important in wound healing, but it is not the most critical factor responsible for the rapid healing in this case.
**Clinical Pearl / High-Yield Fact**
It's worth noting that the rate of collagen synthesis decreases with age, making older adults more susceptible to delayed wound healing. This is why older adults are often at a higher risk of developing pressure ulcers and other types of wounds.
**Correct Answer:** D.