Immune System

By: Jacob Scandalis

Function of the Immune System

Seek out and destroy disease-causing organisms or substances.

Pathogens, Active Immunity, Passive Immunity, Antigens, and Antibody.

Pathogen - a bacteria , virus, or other microorganism that can cause disease.

Active immunity - the immunity that results from the production of antibodies by the immune system in response to the presence of an antigen.

Passive immunity - the short term immunity that results from the inroduction of antibodies from another person or animal.

Antigen - a toxin or other foreign substance that induces an immune response in the body, especially the production of antibodies.

Antibody - a blood protein produced in response to and counteracting a specific antigen. Antibodies combine chemically with substances that the body recognizes as alien, such has bacteria, viruses, and foreign substances in the blood.

Why antibiotics are affective against bacteria but not viruses.

Antibiotics work by interrupting metabolic pathways in prokaryotic cells. Some bacteria prevent the proper formation of a cell wall, and others prevent bacteria from completing cell division. Viruses cannot be killed by antibiotics because viruses lack metabolic pathways. Viruses can reproduce without having their own metaboloic pathways by infecting eukaryotic organisms and hijacking their metabolic pathways, which are not affected by antibiotics.


AIDS - HIV, which causes AIDS, is an acquired viral infection that destroys important white blood cells and weakens the immune system. People with HIV/AIDS become seriously ill with infections that most people can fight odd. These infections are called "opportunistic infections" because they take advantage of weak immune systems. Signs and symptoms consist of fever, fatigue, swollen lymph nodes, diarrhea, weight loss, cough, and shortness of breath.