Innate immunity

Innate immunity is the first line of defense in the immune system. It is a non-specific defense mechanism that comes into play immediately or within hours of an antigen's appearance in the body. The innate immune system is composed of physical and chemical barriers, phagocytic leukocytes, dendritic cells, natural killer cells, and circulating plasma proteins.

Physical and Chemical Barriers[edit | edit source]

The skin and mucous membranes act as physical barriers to prevent the entry of pathogens into the body. The skin is composed of the epidermis and the dermis. The epidermis forms a physical barrier that is impermeable to most infectious agents. The dermis contains cells that can phagocytize bacteria.

Mucous membranes, such as those lining the respiratory, gastrointestinal, and genitourinary tracts, also serve as physical barriers. They secrete mucus, a viscous fluid that traps microbes and other particles.

Phagocytic Leukocytes[edit | edit source]

Phagocytic leukocytes are white blood cells that engulf and destroy microbes. There are several types of phagocytic leukocytes, including neutrophils, monocytes, and macrophages.

Dendritic Cells[edit | edit source]

Dendritic cells are antigen-presenting cells. They capture antigens and present them to T cells, initiating an adaptive immune response.

Natural Killer Cells[edit | edit source]

Natural killer cells are a type of lymphocyte that can kill cells infected with viruses or cancer cells.

Circulating Plasma Proteins[edit | edit source]

Circulating plasma proteins, such as the complement system and cytokines, play a crucial role in innate immunity. The complement system enhances the ability of antibodies and phagocytic cells to clear microbes and damaged cells from the organism, promotes inflammation, and attacks the pathogen's cell membrane.

See Also[edit | edit source]

Innate immunity Resources
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