Immune system

Immunology
Immunology: is the study of host s defense mechanisms against disease, also study the interaction between human and disease agents (pathogenic microbes)., it includes the distinction between self and non self of immune response.
Immunity: refers to the general ability of the host to resist a particular infection or disease.
Antibody (Ab): a protein present in the blood, tissue, fluid and mucous membrane of vertebrate s produce as a result of interaction with an Ag. It has the ability to combine with Ag that stimulated its production.
Antigen (Ag) or immunogen is it is a foreign substance such as protein (pathogen) that reacts with Ab. Not all Ag induce Ab production.
Immune system
It is a complex network of specialized cells , organs and tissues evolved to defend the body against attacks by foreign invaders .The organs involved the immune system are called lymphoid organs, play a role in production and activate lymphocytes they are:-
? Bone morrow.
? Thymus (two lobes that join in front of the trachea).
? Lymph nodes (small organs shaped like beans located throughout the body) .
? Tonsils (two oval masses in the back of throat)
? Payer s patches (Lymphoid tissue in the small intestine).
? Lymphatic vessels (a network of channels throughout the body that carries lymphocytes to the lymphoid tissue in the abdominal cavity).
? Spleen (a fist – size organ located in the abdominal cavity).
? Adenoid (two glands located at the back of the nasal passage).