ANATOMY

Detailed explanation-1: -In the thymus, T cells multiply and are trained to recognize foreign antigens and to ignore the body’s own antigens. T cells are critical for acquired immunity.

Detailed explanation-2: -A macrophage is a large, phagocytic cell that engulfs foreign particles and pathogens. Macrophages recognize PAMPs via complementary pattern recognition receptors (PRRs). PRRs are molecules on macrophages and dendritic cells which are in contact with the external environment and can thus recognize PAMPs when present.

Detailed explanation-3: -Macrophages detect pathogenic microorganisms by expressing pattern recognition receptors (PRRs), which interact with conserved microbe-associated molecular patterns (MAMPs).

Detailed explanation-4: -The immune system recognizes invaders by their antigens, which are proteins on the surface of the invading cells (see Figure 1). Every cell or substance has its own specific antigens, and a person’s cells carry “self-antigens” that are unique to that individual.