Which of the following is NOT a primary function of the integumentary system?

• A. Regulation of body temperature
• B. Protection against pathogens
• C. Synthesis of vitamin D
• D. Production of red blood cells

Answer: (D)

Verified step by step guidance

1. Step 1: Begin by reviewing the primary functions of the integumentary system. The integumentary system includes the skin, hair, nails, and associated glands. Its main roles are protection, temperature regulation, sensation, excretion, and synthesis of vitamin D.
2. Step 2: Analyze each option provided in the question. For example, 'Regulation of body temperature' is a primary function of the integumentary system, as sweat glands and blood vessels in the skin help maintain homeostasis.
3. Step 3: Evaluate 'Protection against pathogens.' The integumentary system acts as a physical barrier, preventing the entry of harmful microorganisms and protecting internal tissues.
4. Step 4: Consider 'Synthesis of vitamin D.' The skin plays a crucial role in producing vitamin D when exposed to sunlight, which is essential for calcium absorption and bone health.
5. Step 5: Examine 'Production of red blood cells.' This is not a function of the integumentary system. Red blood cell production occurs in the bone marrow, which is part of the skeletal system, not the integumentary system.