What is the primary function of Ruffini endings in the dermis?

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: Venous wounds, typically venous stasis ulcers, are relatively painless compared to arterial wounds and improve (decrease) with elevation because this reduces venous pooling and pressure in the lower extremities. Arterial wounds are painful, especially with elevation, due to reduced blood flow. Plantar is a location, not a wound type, and diabetic wounds vary in pain depending on neuropathy but don't specifically decrease with elevation. Venous wounds align with the definition due to their chronic nature, mild discomfort, and response to elevation, which aids venous return, making this the correct answer.

Correct Answer: C

Rationale: An allograft is skin grafted from a donor of the same species, such as cadaver skin used in burn treatment, often as a temporary cover. A homograft is a similar term but less commonly used in modern medical contexts. An autograft is skin from the patient's own body, not a cadaver. A xenograft is from a different species (e.g., pig skin). Since the question specifies cadaver skin (human donor), allograft is the precise term for this type of graft in burn care, making it the correct answer.

Correct Answer: B

Rationale: The integumentary system, primarily the skin, performs several critical physiological roles. It prevents dehydration by acting as a barrier, thanks to the waterproof keratin in the epidermis, which limits water loss. It regulates body fluids indirectly through sweat production and prevents excessive fluid loss. Temperature regulation occurs via sweating and blood vessel dilation or constriction in the dermis. However, the skin does not synthesize vitamin A. Instead, it synthesizes vitamin D when exposed to ultraviolet light, using cholesterol precursors in the epidermis. Vitamin A, essential for skin health and vision, is obtained from the diet (e.g., through beta-carotene) and not produced by the integument. This distinction is key: while the skin processes certain vitamins, its synthetic capacity is limited to vitamin D, not A. Misattributing vitamin A synthesis to the skin overlooks its actual metabolic role and dietary dependency, making this the function it does not perform among the listed options.

Correct Answer: C

Rationale: Hair types in humans vary by developmental stage and location. The reference to Rapunzel's long hair evokes an image of prominent, mature hair, likely scalp hair. Axillary hair grows in the armpits, not typically long or fairy-tale-like. Lanugo is fine, soft hair on fetuses, shed before or shortly after birth, not long or durable. Definitive hair refers to terminal hair coarse, pigmented hair like that on the scalp, eyebrows, or beard which replaces vellus hair (fine, short hair) during development and fits the context of long, strong hair. Angora, a rabbit breed or wool type, is irrelevant to human hair. Scalp hair, as definitive hair, grows long due to extended anagen (growth) phases, often reaching lengths associated with Rapunzel's legendary tresses. This hair type's permanence and prominence in adults align with the literary allusion, distinguishing it from temporary or unrelated hair forms.