Unit 4 AOS 1: Responding to Antigens defs

Cellular pathogens and Non-cellular pathogens

o   Cellular pathogens = made of
cells (e.g. bacteria, parasites, fungi, worms)

o  
Non-cellular
pathogens = lack cells (e.g. viruses, viroids, prions)

Primary pathogens

cause disease any time they are present.

Opportunistic pathogens:

only cause disease when the host’s defenses have been weakened (poor nutrition or stress).

Bacteriophages

are viruses that infect bacteria.

Self-antigens:  

belong to u. those expressed by the body’s own cells. Are found on your own cells that tells the body that they are your own.

Non-self antigens:

·       are found on pathogens or allergens that the body recognises as foreign. don’t belong, not expressed by the body’s own cells. Recognized by the immune system and initiate an immune response.

Antigens:

molecules, or parts of molecules that can bring about immune response (immunogens when trigger an immune response). Recognized by T lymphocytes or antibodies produced by B lymphocytes. Harmful pathogens are recognized in this way, and substances that trigger allergic reactions. Form of communication. Knows to attack, trigger immune response.

Allergens:

non-pathogenic antigens that trigger allergic reactions.