What are the four types of barriers in innate immunity?

Physical, physiological, cellular, cytokine

The correct answer is Option (1) - Physical, physiological, cellular, cytokine.

Innate immunity is a non-specific type of defense mechanism that is present at the time of birth. It provides immediate protection against a wide range of pathogens. The innate immune system consists of four types of barriers:

1. Physical barriers: Physical barriers include the skin, which acts as the main barrier preventing the entry of microorganisms into our body. The skin provides a physical barrier that is difficult for microorganisms to penetrate. Mucus coating of the epithelium lining the respiratory, gastrointestinal, and urogenital tracts also helps in trapping and preventing the entry of microbes.
2. Physiological barriers: Physiological barriers include various substances and conditions within the body that inhibit microbial growth. For example, the acid in the stomach creates an unfavorable environment for many microorganisms. Saliva in the mouth, tears from the eyes, and other bodily secretions also contain substances that help in preventing microbial growth.
3. Cellular barriers: Cellular barriers involve certain types of white blood cells (leukocytes) in our body that can phagocytose and destroy microbes. Examples of such leukocytes include polymorphonuclear leukocytes (PMNL-neutrophils), monocytes, natural killer cells, and macrophages. These cells recognize and engulf pathogens, helping to eliminate them from the body.
4. Cytokine barriers: Cytokine barriers involve the production of proteins called interferons by virus-infected cells. Interferons protect non-infected cells from further viral infection. They play a crucial role in limiting the spread of viral infections within the body.

Together, these four types of barriers in innate immunity provide the body with a rapid and generalized defense mechanism against various pathogens. They form the first line of defense and act as an initial response to protect the body from infection and disease.