Mucous membranes are a part of which of the following defense mechanisms in the human body?

• A. The circulatory system
• B. The innate immune system
• C. The endocrine system
• D. The adaptive immune system

Answer: (B)

Verified step by step guidance

1. Understand the role of mucous membranes in the human body: they act as physical and chemical barriers that prevent pathogens from entering the body.
2. Recall the classification of the immune system into innate and adaptive immunity. The innate immune system provides immediate, non-specific defense mechanisms, including physical barriers like skin and mucous membranes.
3. Recognize that the circulatory and endocrine systems are not primarily involved in direct defense against pathogens but have other physiological roles.
4. Identify that mucous membranes are part of the innate immune system because they provide a first line of defense without requiring prior exposure to a pathogen.
5. Conclude that mucous membranes belong to the innate immune system as a key component of the body's initial, non-specific defense mechanisms.