Skin's Subcutaneous Layer Insulates the Body

Steps:

• Identify skin layers: epidermis, dermis, and subcutaneous (hypodermis).
• Recall functions: epidermis protects, dermis supports structures like vessels and glands, hypodermis stores fat.
• Link insulation to thermoregulation: body heat retention prevents loss in cold environments.
• Match options to layers: fatty tissue is in hypodermis, providing primary insulation.

Why B is correct:

• Fatty tissue in the subcutaneous layer insulates by trapping air and having low thermal conductivity, as defined in human physiology for heat conservation.

Why the others are wrong:

• A. Blood vessels regulate temperature via blood flow but do not insulate.
• C. Hair follicles produce hair for minor insulation in animals, not major in humans.
• D. Sweat glands cool the body through evaporation, aiding heat loss.

Final answer: B