What is the most common protein in the epidermis?

Correct Answer: B

Rationale: Keratin, produced by keratinocytes, is the most common epidermal protein, filling the stratum corneum and providing strength and protection. Elastin is in the dermis for elasticity, not the epidermis. Melanin is a pigment, less abundant than keratin structurally. Cholesterol exists in cell membranes but isn't a dominant protein. Keratin's prevalence, forming the epidermis's tough outer layers, is a hallmark of skin histology, making it the correct answer.

Correct Answer: C

Rationale: The hypodermis, also called subcutaneous tissue, contains adipose tissue that insulates the body against heat loss and stores energy as fat reserves. The epidermis is a thin, avascular layer of epithelial cells, lacking fat. The dermis has connective tissue, glands, and vessels, but not significant adipose. 'Subcutaneous tissue' is synonymous with hypodermis, reinforcing its role. The hypodermis's fat content, cushioning organs and providing a calorie reserve, distinguishes it from the skin's upper layers, making it the correct answer.

Correct Answer: B

Rationale: Pacinian corpuscles, deep pressure and vibration sensors, are located in the dermis, often near its border with the hypodermis, within the reticular layer. The epidermis, avascular and superficial, lacks such receptors. The hypodermis (subcutaneous tissue) may contain some, but they're primarily dermal, integrated with nerve networks there. The dermis's role as the sensory and structural layer, housing various receptors, makes it the correct location for these lamellated corpuscles.

Correct Answer: A

Rationale: The subcutaneous tissue (hypodermis) attaches the skin to underlying muscles and bones via loose connective tissue and fat, allowing mobility while securing position. UV protection is the epidermis's role via melanin. Sweat production occurs in the dermis, not hypodermis. Hair follicle nourishment is dermal, via blood and sebum. The hypodermis's anchoring function, cushioning and connecting, makes attachment its primary purpose, per anatomical structure.

Correct Answer: B

Rationale: Meissner's corpuscles, in the upper dermis, detect light touch and low-frequency pressure, enabling fine tactile sensation like texture. Pain is nociceptors' domain, temperature changes are thermoreceptors', and sweat production is glandular, not receptor-related. Their location and sensitivity to gentle contact distinguish them in the skin's sensory system, making this their primary role.