ANATOMY

Detailed explanation-1: -(a) The innate immune system. The innate immune system provides an early first line of defence against invading pathogens. The cells involved are neutrophils, monocytes, macrophages and dendritic cells, which all interact with the adaptive immune system.

Detailed explanation-2: -Innate, or nonspecific, immunity is the defense system with which you were born. It protects you against all antigens. Innate immunity involves barriers that keep harmful materials from entering your body. These barriers form the first line of defense in the immune response.

Detailed explanation-3: -Innate immune system. The innate immune system is the first line of defense against pathogens.

Detailed explanation-4: -Successful innate immune protection is achieved through two steps. First, identifying targets, such as pathogens and abnormal tissues and cells. Second, by orchestrating humoral and cell effectors to neutralize and eliminate the identified targets.

Detailed explanation-5: -The adaptive immune system (AIS) in mammals, which is centred on lymphocytes bearing antigen receptors that are generated by somatic recombination, arose approximately 500 million years ago in jawed fish.