In general, skin cancers

Correct Answer: C

Rationale: Skin cancers, like melanoma and squamous cell carcinoma, are strongly linked to UV exposure from the sun, and limiting this exposure (via sunscreen, clothing, or shade) reduces risk significantly. They're not always easily treatable melanoma can be deadly if it metastasizes. Poor hygiene doesn't cause skin cancer; it's unrelated to UV-induced DNA damage. They don't affect only the epidermis; advanced cases invade the dermis and beyond. Public health data supports sun protection as a proven preventive measure, making this the most accurate statement.

Correct Answer: B

Rationale: The nail's anatomy includes specific structures, but 'nail head' is not among them. The nail body (or plate) is the hard, visible keratinized portion covering the nail bed. The nail matrix, beneath the proximal nail fold, is the growth zone where new cells form, pushing the nail forward. The eponychium, or cuticle, is the skin fold at the nail's base, protecting the matrix. These are standard nail components, derived from epidermal keratinization. 'Nail head' is not a recognized anatomical term in human nail structure possibly a confusion with other contexts (e.g., a tool) or a misnomer. In contrast, terms like lunula (the white crescent) or hyponychium (skin beneath the nail's free edge) are valid but not listed. The absence of 'nail head' in anatomical texts and its irrelevance to nail growth or function distinguish it as the incorrect option, aligning with standard dermatological descriptions.

Correct Answer: B

Rationale: Lipid-soluble molecules pass most easily through the epidermis due to its structure. The stratum corneum, rich in keratin and lipids (e.g., ceramides, cholesterol), forms a hydrophobic barrier. Lipid-soluble substances, like steroids or fat-soluble vitamins (A, D, E, K), dissolve into this lipid matrix, diffusing through cell membranes and intercellular spaces. Proteins, large and often hydrophilic, cannot penetrate this barrier, remaining excluded unless via wounds. Water-soluble compounds, like glucose, struggle to cross without carriers, as the corneum repels water. Salts, ionic and water-soluble, face similar resistance, though sweat ducts allow minimal passage. Transdermal drug delivery exploits this, using lipid-based patches for absorption. The epidermis's avascularity and lipid composition favor nonpolar molecules, a principle backed by pharmacological and physiological research, distinguishing lipid-soluble penetration from polar or large substances.

Correct Answer: B

Rationale: Sensory receptors in the skin detect stimuli like touch, pressure, or pain. Meissner corpuscles sense light touch, root hair plexuses detect hair movement, and nociceptors register pain all are receptors in the dermis or epidermis. Apocrine glands, however, are sweat glands associated with hair follicles, secreting sweat in response to stress or hormones, not sensing stimuli. They're part of the skin's excretory system, not its sensory network. This functional distinction excludes apocrine glands from being sensory receptors, aligning with their role in secretion rather than perception.

Correct Answer: C

Rationale: Sudiferous glands are sweat glands with two types: eccrine, which secrete watery sweat through ducts directly to the skin surface for cooling, and apocrine, which secrete thicker sweat into hair follicles, often in areas like the armpits. Sebum is secreted by sebaceous glands, not sudiferous. Cerumen (earwax) comes from ceruminous glands, not sweat glands. The dual mechanism eccrine to the surface, apocrine to follicles defines sudiferous glands' function in thermoregulation and excretion, making this the comprehensive answer.