Which list below contains functions that are NOT performed by the integumentary system?

Correct Answer: D

Rationale: The skin protects, secretes sebum, aids immunity, regulates temperature, excretes sweat, synthesizes vitamin D, perceives stimuli, and protects all true functions. It doesn't synthesize vitamin E, which is dietary, not skin-produced. 'Social function' (e.g., appearance) is a byproduct, not a primary physiological role like temperature regulation. The inclusion of vitamin E synthesis, an incorrect function, makes this list the one with non-integumentary roles.

Correct Answer: A

Rationale: The epidermis is the outermost layer of the skin, forming a protective barrier against the environment with its stratified squamous epithelium, primarily composed of keratinocytes and topped by the stratum corneum. The dermis lies beneath it, containing connective tissue and glands, not the surface. The hypodermis, also called subcutaneous tissue, is deeper still, beneath the dermis, and consists of fat and connective tissue, not the outermost layer. While 'subcutaneous tissue' is synonymous with hypodermis, it's not the skin's surface. The epidermis's position as the topmost layer, shielding against pathogens and dehydration, makes it the correct answer, consistent with skin histology.

Correct Answer: D

Rationale: Nails, hardened epidermal extensions, aid manipulation and gripping by providing a rigid surface for fingertips, enhancing dexterity and tool use. Temperature regulation involves sweat and vessels, not nails. Sensation occurs via skin receptors, not nails themselves. UV protection is melanin's role, not nails'. The nails' mechanical support, protecting fingertips and assisting in tasks like scratching or picking, makes manipulation their key function, a practical role in the integumentary system.

Correct Answer: D

Rationale: Thermoreceptors, specialized nerve endings in the dermis and epidermis, detect temperature changes, signaling heat or cold to maintain homeostasis. Meissner's corpuscles sense light touch, Ruffini endings detect stretch and sustained pressure, and Merkel cells (via discs) sense continuous touch, none primarily temperature-focused. Thermoreceptors' sensitivity to thermal stimuli, distinct from mechanical or tactile roles, makes them the correct receptor type, essential for skin's sensory function.

Correct Answer: C

Rationale: Excretion via skin involves sweat glands eliminating waste like salts, urea, and water, a minor but real function alongside thermoregulation. Thermoregulation cools via sweat evaporation, sensation detects stimuli, and protection shields from harm, but only excretion directly addresses waste removal. This process, though secondary to kidney function, occurs through eccrine glands, making it the correct function.