Zoology - Human Health and Diseases Question with Solution | TestHub

The innate immune system, also known as non-specific immune system, is the first line of defence. It comprises the cells and mechanisms that defend the host from infection by other organisms in a non-specific manner. This means that the cells of the innate system recognize and respond to pathogens in a generic way. Innate Immunity is present at the time of birth. Innate immunity consists of four types of barriers.

$•$ Physical barriers: Skin on our body is the main barrier which prevents entry of the micro-organisms. Mucus coating of the epithelium lining the respiratory, gastrointestinal and urogenital tracts also help in trapping microbes entering our body.

$•$Physiological barriers: Acid in stomach, saliva in the mouth, tears from eyes all prevent microbial growth.

$•$Cellular barriers:Certain types of leukocytes (WBC) of our body such as polymorph nuclear leukocytes (PMNL-neutrophils) and monocytes and natural killer cells in the blood as well as macrophages in tissues can phagocytise and destroy microbes.

$•$Cytokine barriers:Virus-infected cells secrete proteins called interferon which protect non-infected cells from further viral infection.