The Primary Immune Response occurs at first contact with the pathogen. The body takes several days to build up a sufficient amount of antibodies. There is a three-pronged attack in response to primary exposure to infection, which is non specific and is often referred to as the second line of defense. It involves: 1.

The organism enters the body by one of the entry routes (in this case oral) and is taken up by the epithelial cells of the stomach. Here a host specific receptor-ligand reaction occurs, whereby the ligand on the pathogen attaches to the receptor proteins on the host.

Phagocytosis is when a white blood cell - or "phagocyte" - engulfs a pathogen that has entered the body and has made it past the body's physical barrier defences.The phagocyte first locates the pathogen (as the pathogen naturally releases chemicals that the phagocyte can detect.)

These enzymes are called lysozymes. After destroying the engulfed baceria, antigens from the pathogen are moved to the outside of the cell membrane, allowing the phagocyte to become an antigen presenting cell which activates further activation of the immune response to the bacteria.

The lysosome then releases lysozymes which hydrolyse the pathogen. The bacterial meningitis antigens are then presented on the macrophage cell surface membrane. Macrophages present these antigens to T lymphocytes causing clonal selection of the T lymphocyte that recognises the antigen as foreign, then clonal expansion occurs by mitosis.

A pathogen is a microorganism that causes a disease. Pathogens spread communicable diseases meaning that they are transmitted person to person and are infectious. Types of pathogens include bacteria, fungi, viruses and protists. Not all microorganisms are pathogens but here are some examples of microorganisms which are harmful. Bacteria: Salmonella

They can also produce antibodies to destroy particular pathogens and antitoxins to counteract any toxins produced by the pathogen. Memory cells can form which then confer immunity to that pathogen by creating specific antibodies and remaining in the system.

Once the pathogen has entered their body their immune response will be stimulated. The two types of white blood cells - phagocytes and lymphocytes will be secreted. Lymphocytes secrete antibodies which bind to the specific antigens on the surface of the pathogen. The phagocytes can then engulf and destroy the pathogen.

Pathogens are microorganisms that cause disease. They may be bacteria, viruses, protists or funghi. They can infect animals and plants, causing a wide range of di...

If we get infected again by the same pathogen in the future, the white blood cells can produce the antibodies so quickly to kill the pathogens before they make us ill. Producing antitoxins: Invading bacteria can produce toxins to make us ill. WBC produce antitoxins to neutralise (make it less toxic) the toxins.