Author: Aaron Mullally

This lesson will give an overview of the body's three lines of defense against a pathogen.

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  • Pathogen

    Any disease-causing agent that we are exposed to (bacteria, virus, fungus, parasite, etc.)

  • Physical Barriers

    Consists of skin and mucous membranes, physical barriers are our first line of defense against pathogens. Physical barriers are part of our non-specific immunity.

  • Innate Immunity

    Also known as non-specific immunity, innate immunity consists of general physiologic responses (fever, inflammation, etc.) that can affect the entire body.

  • Adaptive Immunity

    Also known as specific immunity, adaptive immunity is carried out by T & B lymphocytes and reacts to specific antigens of cells; adaptive immunity also produces memory cells to target the same pathogen if we are ever exposed to it again.