Clinical Microbiology, Virology and Infectious Diseases

Infection and Immune System

Human immune systems are classified into two categories: innate (natural) immunity and adaptive (acquired) immunity. There are major differences between the two divisions, but they share some cell functions and components. All living organisms are subjected to get attacked from disease-causing agents or pathogens. When species become more complex, this mechanism of defense becomes more sophisticated. Multicellular animals have devoted cells or tissues to deal with infection. Other rejoinders are slower but are more adapted to the infecting agent. Jointly, these protections are known as the immune system. The main portions of the immune system are: the natural barriers (skin, mucous membranes, etc.), nonspecific cells (phagocytes, natural killer cells, etc.), and nonspecific molecules (complement, interferon, etc.). Furthermore, the immune system's response to microorganism invasion depends on many factors, such as nutrition, general health, age, and any human host's genetic makeup.

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  Innate immune system

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  Adaptive immune system