IMMUNOLOGY

Detailed explanation-1: -The human body has three primary lines of defense to fight against foreign invaders, including viruses, bacteria, and fungi. The immune system’s three lines of defense include physical and chemical barriers, non-specific innate responses, and specific adaptive responses.

Detailed explanation-2: -The immune system fights germs and foreign substances on the skin, in the tissues of the body and in bodily fluids such as blood. The immune system is made up of two parts: the innate, (general) immune system and the adaptive (specialized) immune system.

Detailed explanation-3: -There are two basic ways the body defends against pathogens: nonspecific innate immunity and specific adaptive immunity.

Detailed explanation-4: -Primarily, the innate response can be categorized based on external and internal defenses. While the external defense mechanisms such as skin and teardrops offer the first line of protection against harmful pathogens, the internal mechanism, i.e., stomach acid and cellular defenses, provide the second line of defense.