Immunology is a study about molecules, cells, organs and systems responsible for recognition and disposal of foreign materials from our body. Immune system defenses us from harmful consequences.
Immune system is divided into two types:
- Innate immunity
- Adaptive immunity
Innate immunity is also called non-clonal defense mechanism because there is no individual cell clone is required for their specific development. All individuals are born with this. Innate immunity includes mechanical barriers (e.g. skin, mucosa membrane), physicochemical barrier (e.g. hydrochloric acid in stomach), antibacterial substance (e.g. lysozyme), normal intestinal transit and normal flow and phagocytosis.
Adaptive immunity is called specific immunity where it is induced during the life of individual in a complex event. The important cells are lymphocytes (B cells and T cells). Clonal selection occurs where the large numbers of lymphocytes are produced through mitosis in body.
Basically, the immune system in body is also categorized into first, second and third line defense systems. The innate immunity acts as first and second lines immune responses toward foreign materials. While, the adaptive immunity acts as third line immune response.