Here's why:
* It's present from birth: Innate immunity is the body's initial, non-specific defense mechanism, present from birth.
* It's a rapid response: It acts quickly to identify and eliminate pathogens.
* It's not specific: It doesn't target specific pathogens, but rather recognizes broad patterns associated with infection.
Examples of innate immunity in mammals include:
* Physical barriers: Skin, mucous membranes, and cilia
* Chemical barriers: Stomach acid, enzymes in saliva and tears
* Cellular defenses: Phagocytic cells (like macrophages and neutrophils) and natural killer (NK) cells
* Inflammation: A localized response to infection that helps recruit immune cells
* Complement system: A cascade of proteins that helps destroy pathogens
While mammals also have adaptive immunity (which develops over time and is highly specific to individual pathogens), innate immunity is essential for initial protection against infection.
