7A - Detecting Pathogens

Pathogen

an agent that causes disease

Antigen

any molecule that may trigger an immune response

Non-self antigen

 a molecule from outside the body that is recognised by the immune system and initiates an immune response. Also known as a foreign antigen

Major histocompatibility complex (MHC) markers

a group of proteins present on the surface of all self-cells that enables the immune system to distinguish it from non-self material. Also known as MHC proteins, MHC molecules, or self-antigens

major histocompatibility complex class I (MHC Class I) markers

expressed on all nucleated cells in the body. These mark cells as ‘self’ so that the immune system doesn’t attack them

major histocompatibility complex class II (MHC Class II) markers

expressed on antigen-presenting cells, which interact with T helper cells in the process of antigen-presentation

Autoimmune disease

 a disease in which an individual’s immune system initiates an immune response against their own cells

Allergen

a non-pathogenic antigen that triggers an allergic reaction

Allergic Reaction

an overreaction of the immune system to a nonpathogenic antigen

Cellular pathogen

 a pathogen that has a cellular structure and exhibits the processes of a living organism. Examples include bacteria, fungi, protozoa, and parasites

Non-cellular pathogen

a pathogen that neither has a cellular structure nor exhibits the processes of a living organism. Examples include viruses and prions

Lysis

the disintegration or rupturing of a cell

Hypahe

branching filaments of a fungus which help absorb nutrients from the environment

Parasite

an organism that lives in or on another organism, usually deriving nutrition from the host organism