Hint: Immunity is nothing but the ability of microorganisms to resists themselves from the harmful pathogens that enter the body, it is a defense system of the body, and it consists of various components that are responsible to provide pathogen-specific immunity.
Majorly immunity is of two types, they are Innate and acquired immunity.
Innate immunity: it is also called as non specific immunity, it is present in the organism from the birth, and this immunity has barriers which are act as a defensive system, and main barriers are skin, hair, respiratory tract, and gastrointestinal tract, etc This innate immunity consists of various types of cells to kills the foreign particles, they are neutrophils, eosinophils, basophils, macrophages, mast cells, phagocytes, etc.
The major functions of the human innate immunity are:
- Provide cells at the site of infection, through the chemical factors such as cytokines.
- To provide a cascade mechanism, for identifying the bacteria, and other organisms and antibody complexes
- Identification and removal of foreign substances present in the tissues, cells by white blood cells.
Innate immunity provides both cellular barriers and anatomical barriers. The anatomical barriers include skin, gastrointestinal tract, respiratory tract, etc. When coming to cells of innate immunity, they consist of
Mast cells: These are present in the connective tissue, and mucous membranes, they are mainly associated with defense mechanisms and wound healing, they are also responsible for allergy and anaphylaxis.
Phagocytes: These are the immune cells that engulf the pathogens, which include macrophages, neutrophils, and dendrite cells, this cell provides apoptosis. Neutrophils, along with eosinophils and basophils provide defense against various organisms by releasing various toxins against them. Natural killer cells are also a type of innate immunity, where these cells attack virus infected or tumor cells.
Note: Most of the innate immune leukocytes are not like other cells in the body, where they do not divide and reproduce on their own, instead of they formed from multipotent hematopoietic stem cells present in the bone marrow of the long bones.