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

Correct Answer: A

Rationale: Skin waterproofs via the stratum corneum, produces vitamin D with UV exposure, and aids immunity via Langerhans cells, but fat storage occurs in the hypodermis (subcutaneous layer), not the integument (epidermis and dermis). The hypodermis's role in energy storage is distinct from skin functions, which focus on protection, synthesis, and sensation. Fat storage's exclusion from the integument proper, per anatomical definition, makes this the non-function.

Correct Answer: B

Rationale: Sebaceous glands, located in the dermis, primarily produce sebum, an oily substance that lubricates skin and hair, preventing dryness and aiding waterproofing. Sweat production is the role of sudiferous glands (eccrine and apocrine), not sebaceous. Melanin comes from melanocytes in the epidermis, not glands. Collagen is synthesized by fibroblasts in the dermis, not secreted by glands. Sebum's lipid-rich composition, secreted into hair follicles, distinguishes sebaceous glands' function, essential for skin and hair maintenance, making this the accurate primary role.

Correct Answer: C

Rationale: Collagen and elastin fibers in the dermis provide strength and elasticity: collagen, abundant in the reticular layer, resists stretching, while elastin allows recoil, maintaining skin's resilience. Blood vessels supply nutrients, not structure. Sweat glands regulate temperature, not toughness. Nerve endings sense stimuli, not support. These fibers, produced by fibroblasts, form the dermis's extracellular matrix, critical for skin's durability and flexibility, making them the key components.

Correct Answer: B

Rationale: Blood vessels in the dermis regulate body temperature by dilating to release heat (vasodilation) or constricting to conserve it (vasoconstriction), aiding thermoregulation alongside sweat glands. Sweat production is glandular, not vascular. Melanin and sebum come from melanocytes and sebaceous glands, respectively, not vessels. The dermis's rich vascular network adjusts blood flow to maintain homeostasis, making temperature regulation their primary role, per circulatory-skin interaction.

Correct Answer: B

Rationale: Sweat glands, especially eccrine, primarily regulate temperature by secreting sweat for evaporative cooling and excrete waste like salts and urea, dual roles in homeostasis. Lubrication is sebum's job, melanin production is melanocytes', and UV protection is melanin's effect, not glands'. Sweat's cooling and minor excretory functions define their primary purpose, making this the accurate answer.