When we are attacked by microorganisms and foreign particles, the body fights against these pathogens.

The system in charge of this task is called the Immune System and it is able to distinguish harmful agents such as viruses, worms or parasites that your body needs to distinguish from its own healthy cells and tissues in order to function properly. Detection is complicated as pathogens can evolve rapidly and trick our immune system and allow pathogens to infect you causing serious illness.


In humans, the gastrointestinal tract, also called the digestive tract, is the organ system that is responsible for digesting food to extract energy and nutrients when it is consumed. The main functions of the gastrointestinal tract are ingestion, digestion, absorption and excretion and it constitutes 70% of the immune system. This is where most of the body’s biological processes dedicated to protecting you from disease by identifying and killing pathogenic and tumor cells take place.


Disorders in the immune system can cause illness. Immunodeficiency occurs when the immune system is less or more active than normal, resulting in recurrent and life-threatening infections.


Immunodeficiency can be the result of a genetic disease, such as severe combined immunodeficiency, or be caused by drugs or infection, such as acquired immunodeficiency syndrome (AIDS), which is caused by the retrovirus HIV.


Autoimmune diseases, on the other hand, are the result of an overactive immune system that attacks normal tissues as if they were foreign organisms.


Common autoimmune diseases include Hashimoto’s thyroiditis, rheumatoid arthritis, type 1 diabetes mellitus and lupus erythematosus. Immunology covers the study of all aspects of the immune system that have significant relevance to human health and disease.