Immune system for moodle

Viruses are not considered alive as they are not made of cells, do not use energy, and rely on host cells to express their genes and replicate. The immune system has non-specific defenses like skin, mucus, and stomach acid as a first line of defense and the inflammatory response as a second line. The immune system also has specific defenses triggered by antigens on pathogens including antibodies that bind to antigens and mark them for destruction by macrophages. The immune system develops immunological memory allowing a stronger secondary response compared to the primary response. Immune system disorders can include allergies where the immune system overreacts or autoimmune disorders where it mistakenly attacks the body's own cells.