Loss of body fluids through the integument is restricted by:

Correct Answer: A

Rationale: The skin's ability to restrict fluid loss is a vital protective function, primarily achieved through its outermost layer, the stratum corneum, which is rich in keratin. Keratin is a tough, fibrous protein that forms a waterproof barrier, preventing water from escaping the body and protecting against environmental damage. The stratum germinativum, the deepest epidermal layer, is responsible for cell production, not water retention. Carotene, a pigment, contributes to skin color but has no role in fluid regulation. Melanocytes produce melanin for UV protection, not water barrier functions. The dermis, while supportive, relies on the epidermis specifically keratin for this role. In conditions like burns, where keratin is compromised, fluid loss increases dramatically, underscoring its importance. Evolutionary adaptations, such as thicker keratin layers in terrestrial animals, further highlight its role in preventing desiccation. Thus, keratin stands out as the key structural component limiting fluid loss through the integument, distinguishing it from the other options' unrelated functions.

Correct Answer: D

Rationale: The papillary layer of the dermis is the uppermost layer of the dermis, characterized by loose connective tissue and finger-like projections (papillae) that interlock with the deepest layer of the epidermis, the stratum basale. The stratum basale, also called the basal layer, is where new skin cells are produced and it rests directly on the papillary dermis, forming a strong connection via the basement membrane. The stratum spinosum lies above the basale and is thicker, with spiny cells, but it's not in direct contact with the papillary layer. The stratum granulosum is higher up, involved in keratinization, and the stratum corneum is the outermost dead layer, far from the dermis. The anatomical proximity and functional relationship between the papillary layer and stratum basale, including nutrient exchange and anchoring, make it the most closely associated layer.

Correct Answer: B

Rationale: Sebaceous glands are oil-producing glands typically associated with hair follicles, secreting sebum to lubricate hair and skin. They are not sweat glands, which produce sweat (eccrine and apocrine glands have different roles). They don't function in response to touch; that's more relevant to sensory receptors like Merkel cells. Nor do they release a watery solution of salt and waste that describes eccrine sweat glands. Their anatomical and functional link to hair follicles, where they empty sebum into the follicle, is a classic feature of skin histology, making this the correct association.

Correct Answer: C

Rationale: Bedsores (pressure ulcers) develop from prolonged pressure on skin, cutting off blood flow and causing tissue damage, often in bedridden patients. They're preventable by eliminating pressure points through repositioning, cushions, or mattresses, relieving compression on vulnerable areas like the heels or sacrum. Topical moisturizers may help skin health but don't treat established sores. Deep massages could worsen damage, not cause it. Dry skin isn't the cause; ischemia from pressure is. Prevention via pressure relief is a standard clinical approach, making this the correct answer.

Correct Answer: B

Rationale: Goosebumps occur when small muscles attached to hair follicles contract, causing hairs to stand upright and skin to pucker. These are the arrector pili muscles, smooth muscles in the dermis anchored to the hair follicle base and the epidermal-dermal junction. When stimulated by cold or emotion (via the sympathetic nervous system), they contract, pulling hairs erect, an evolutionary vestige from furrier ancestors to trap heat or signal threat. Sebaceous glands secrete sebum to lubricate hair and skin, not to cause goosebumps. 'Cappilary' (likely a typo for capillary) refers to blood vessels, which adjust for temperature but don't directly produce goosebumps. Collagen provides dermal strength but is a passive fiber, not a muscle. The arrector pili's action is involuntary, linked to thermoregulation and emotional response, and its distinct role in piloerection visible as goosebumps sets it apart as the key structure in this phenomenon.