Which lines of resistance are encompassed by innate resistance?

• A. First and second lines of resistance
• B. First and third lines of resistance
• C. Only the second line of resistance
• D. First, second, and third lines of resistance

Answer: (A)

Innate resistance refers to the body's immediate and non-specific defense mechanisms that respond to pathogens. This system includes the first and second lines of resistance.

The first line of resistance primarily consists of physical and chemical barriers that prevent pathogens from entering the body. These include skin, mucous membranes, and secretions such as saliva and tears that contain antimicrobial substances.

The second line of resistance involves internal defense mechanisms that kick in if pathogens breach the first line. This includes the inflammatory response, activation of various types of white blood cells, and the release of signaling molecules known as cytokines to coordinate the immune response.

The third line of resistance is part of the adaptive immune system, which is specific and develops over time as the body is exposed to various pathogens. This includes the production of antibodies and memory cells tailored to specific pathogens, making it distinct from the innate immune responses included in the first and second lines.

Therefore, the correct choice encompasses the first and second lines of resistance, highlighting the nature of innate immunity as the initial response that is quick and generally non-specific against a wide range of pathogens without the need for prior exposure.