Which of the following helps prevent water loss through skin?

AIIMS Nagpur NO- 2020

Applied Physiology

Easy

Appeared in: AIIMS Nagpur NO- 2020

Explanation

Keratin is a fibrous structural protein that is the primary component of the epidermis, hair, and nails.
The outermost layer of the epidermis, the stratum corneum, is composed of dead, flattened cells (corneocytes) that are filled with keratin.
This keratinized layer creates a tough, water-resistant barrier that prevents excessive water loss from the body (transepidermal water loss) and protects against environmental insults.

Option B: Melanin's primary function is to absorb ultraviolet (UV) radiation, protecting deeper skin layers from sun damage. It determines skin color but does not have a primary role in preventing water loss.
Option C: Collagen is the main structural protein of the dermis, the layer below the epidermis. It provides tensile strength and elasticity to the skin, but it does not form the waterproof barrier on the surface.
Option D: Carotene is a yellow-orange pigment obtained from the diet that can accumulate in the stratum corneum and subcutaneous fat. It contributes to skin color and is a precursor to Vitamin A, but it does not play a role in skin hydration.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Integumentary System: Barrier Function of the Skin as background academic context rather than a clinical decision trigger.
Understanding the skin's barrier function is crucial for nurses, especially in managing conditions like extensive burns, where the loss of the keratinized epidermis leads to massive fluid and electrolyte loss, making fluid resuscitation a top priority.
Patient education on skin care often involves recommending emollients or moisturizers. These products work by supporting or supplementing the skin's natural lipid and keratin barrier to reduce water loss and maintain hydration.
What if? If a patient has a genetic disorder like ichthyosis vulgaris, caused by mutations affecting the filaggrin protein (which helps organize keratin filaments), their skin barrier is impaired. This leads to chronically dry, scaly skin and an increased need for intensive moisturizing to prevent cracking and infection.

How to Approach the Question

First, identify the key function described in the question: 'prevent water loss through skin'.
Second, recall the main components of the skin and their primary roles. The skin consists of the outer epidermis and the inner dermis.
Third, evaluate each option based on its location and function. Keratin forms the outermost physical barrier, melanin is a pigment for UV protection, collagen provides strength in the deeper dermis, and carotene is another pigment.
Conclude that the protein forming the outermost, water-resistant layer (Keratin) is the correct answer for preventing water loss.

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