Which component of the dermis provides the skin with its strength and elasticity?

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: 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.

Correct Answer: B

Rationale: Sensation detects extreme temperature changes (thermoreceptors) and harmful stimuli (nociceptors for pain), alerting the body to potential damage. Thermoregulation adjusts temperature, lubrication moisturizes, and vitamin D synthesis uses UV, none sensing stimuli. The skin's sensory receptors, embedded in the dermis and epidermis, enable this protective awareness, making sensation the correct function.

Correct Answer: B

Rationale: The dermis maintains elasticity and prevents wrinkles via collagen and elastin fibers, which degrade with age, causing sagging. The epidermis provides a barrier, not elasticity. The hypodermis (subcutaneous tissue) insulates but doesn't directly affect wrinkles. The dermis's structural proteins, produced by fibroblasts, are key to skin firmness, making it the correct layer.