Which of the following is NOT a function of the skin?

Correct Answer: C

Rationale: The skin regulates temperature via sweat glands and blood vessels, senses stimuli through receptors, and protects against pathogens with its physical barrier and immune cells, but hormone production isn't a primary skin function. Hormones like cortisol or testosterone are produced by endocrine glands (e.g., adrenals, gonads), not skin. While skin synthesizes vitamin D, a prohormone, this is a metabolic process, not hormone production in the endocrine sense. Temperature regulation involves sweating and vasodilation, sensation uses nerve endings, and pathogen protection relies on the stratum corneum and Langerhans cells. Hormone production's absence from skin's core roles distinguishes it as the incorrect function here.

Correct Answer: C

Rationale: Sebum, an oily secretion from sebaceous glands, lubricates skin and hair, preventing dryness and brittleness while adding a minor protective layer. UV protection is melanin's role, not sebum's. Temperature regulation involves sweat and vessels, not oil. Melanin production is melanocytes' task, not glands'. Sebum's lipid content, delivered via hair follicles, maintains skin suppleness and waterproofing, making lubrication its primary function, per skin physiology.

Correct Answer: B

Rationale: Melanin, produced by melanocytes, protects against UV radiation by absorbing it, preventing DNA damage and reducing skin cancer risk, darkening as a shield (tanning). Melatonin regulates sleep, not UV defense. Sebum lubricates, not protects from UV. Collagen provides structure, not photoprotection. Melanin's UV-absorbing property, distributed in the epidermis, is the skin's primary anti-radiation mechanism, making it the correct answer.

Correct Answer: A

Rationale: Ruffini endings, in the dermis, detect sustained pressure and skin stretch, contributing to proprioception and grip stability, often responding to vibration too. Light touch and texture are Meissner's corpuscles' role, temperature changes are thermoreceptors', and sweat production is glandular. Their mechanoreceptive function for deep pressure distinguishes them, making this their primary role.

Correct Answer: C

Rationale: Meibomian glands, in the eyelids (part of the integumentary system), secrete an oily substance into tear film, lubricating the eyes to prevent evaporation and dryness. Temperature regulation involves sweat glands, tears come from lacrimal glands (not integumentary), and sweat is from sudiferous glands. Their role in eye lubrication, maintaining tear stability, makes this their primary function.