Which of the following is NOT a cell?

Correct Answer: C

Rationale: Macrophages are immune cells, chondroblasts form cartilage, and melanocytes produce melanin all are cell types in the body. A lysosome, however, is an organelle within cells, containing enzymes for digestion, not a cell itself. The suffixes '-phage,' '-blast,' and '-cyte' denote cells, while lysosome's role as a subcellular structure distinguishes it. In skin context, macrophages and melanocytes are dermal/epidermal cells, but lysosome's intracellular nature excludes it from being a cell, making it the correct non-cell choice.

Correct Answer: A

Rationale: The integumentary system includes the skin (epidermis and dermis), hair, nails, and glands like sebaceous glands. The hypodermis, or subcutaneous layer, lies beneath the dermis and isn't considered part of the integument proper, despite its adjacency. Sebaceous glands in the dermis, fingernails (epidermal derivatives), and the stratum corneum (epidermis) are all integumentary components. The hypodermis's exclusion, as superficial fascia, is a consistent anatomical distinction, making it the odd one out.

Correct Answer: D

Rationale: The dermis is vascularized, with blood vessels supplying nutrients, while the epidermis is avascular, relying on diffusion from dermal capillaries. The epidermis is epithelial cells, not connective tissue (dermis has that). The dermis isn't exterior (epidermis is) and is part of the skin, not excluded. Vascularity's contrast epidermis lacking vessels, dermis rich with them defines their structural and functional difference, making this the accurate distinction.

Correct Answer: A

Rationale: Sudiferous glands (sweat glands) produce sweat, either watery (eccrine) or thicker (apocrine), for thermoregulation and excretion. Sebum is from sebaceous glands, cerumin (cerumen) from ceruminous glands, and 'merocrin' is a typo or misnomer (merocrine describes eccrine secretion mode, not a substance). Sweat's role as the sudiferous output, distinct from other glandular products, confirms it as the correct secretion.

Correct Answer: A

Rationale: Sweat glands, primarily eccrine, regulate body temperature by secreting sweat, which evaporates to cool the skin, a key thermoregulatory mechanism. Melanin production is melanocytes' job, not glands'. Hair follicle nourishment involves blood vessels and sebum, not sweat. Joint lubrication is synovial fluid's role, not skin-related. Sweat glands' production of water and electrolytes, triggered by heat or exercise, directly supports homeostasis by dissipating heat, making temperature regulation their primary function, widely recognized in physiology.