The skin fibres are arranged in bundles known as:

Correct Answer: B

Rationale: Skin fibers, primarily collagen in the dermis, are arranged in bundles called lines of cleavage (or Langer's lines). These parallel alignments reflect the natural tension and orientation of collagen and elastic fibers in the reticular dermis, giving skin strength and flexibility. Surgeons use these lines for incisions, as cuts along them heal with less scarring due to minimal fiber disruption. The zone of hyperaemia is a region of increased blood flow, not a fiber structure. Epidermal ridges, on the epidermis, form fingerprints from dermal papillae, not fiber bundles. The stratum lucidum, an epidermal layer in thick skin, consists of dead cells, not fibers. Lines of cleavage are a dermal feature, visible in histological sections as organized collagen, critical for skin's mechanical properties and surgical outcomes, distinguishing them from epidermal or vascular terms.

Correct Answer: C

Rationale: The stratum germinativum, also called the stratum basale, is the deepest epidermal layer where keratinocytes rapidly divide via mitosis to replenish the epidermis, replacing cells lost from the surface. The stratum lucidum, in thick skin, is a thin, dead layer above the basale, not dividing. The papillary and reticular dermal layers are in the dermis, containing connective tissue, not keratinocytes. The germinativum's name (from 'germinate') reflects its role as the regenerative base, a key feature of epidermal renewal confirmed by histological studies.

Correct Answer: D

Rationale: Sebaceous glands secrete sebum, an oily substance, into hair follicles to lubricate hair and skin, found in the dermis. Apocrine glands secrete sweat into hair follicles, not oil. Eccrine glands secrete watery sweat directly to the skin surface via ducts. Ceruminous glands produce cerumen (earwax), not oil for hair follicles. Sebaceous glands' association with follicles and their oily output distinguish them in skin physiology, making them the correct gland type for this function.

Correct Answer: A

Rationale: The epidermis is the outermost skin layer, encompassing sublayers like the stratum corneum and germinativum, serving as the body's protective shield. The dermis lies beneath it, with the papillary dermal layer as its upper part, still deeper than the epidermis. The stratum germinativum (basale) is the deepest epidermal sublayer, not the most superficial. As a whole, the epidermis sits atop the dermis, making it the most superficial layer in skin anatomy, consistent with its role as the first barrier to the environment.

Correct Answer: C

Rationale: Transdermal administration means a drug is absorbed through the skin into the bloodstream for systemic effects (e.g., nicotine patches), not just local action (topical). Injection into the dermis is intradermal, and into subcutaneous fat is hypodermic, both distinct from surface application. 'Trans' indicates crossing the skin barrier, requiring penetration of the stratum corneum to reach circulation, a method reliant on skin permeability, making systemic action the defining feature.