Key definitions
Antigen: A protein found on the surface of an organism that is recognised as non-self by the immune
system and stimulates an immune response.
Antibody: proteins with specific binding sites synthesised by B plasma cells
Agglutination: The clumping together of cells or particles caused by antibodies which assists
phagocytosis.
Helper T cell: A type of T cell in the immune system that stimulates cytotoxic T cells, B cells and
phagocytes.
Herd immunity: A type of disease immunity that occurs when a large proportion of a population are
vaccinated against a disease which prevents the spread of the disease to unvaccinated individuals.
Human Immunodeficiency Virus (HIV): A virus that attacks T cells in the immune system and can lead to
AIDS (acquired immune deficiency syndrome).
Immunity: protection against disease provided by the immune system
Immune response:
Lysosomes: Membrane-bound vesicles found in the cytoplasm that contain a hydrolytic enzyme called
lysozyme.
Lysozymes: digestive enzymes
(Non-specific immunity)
The body’s first line of defence is to form physical and chemical barriers to entry. This response is
immediate and the same for all pathogens. e.g skin provides a physical barrier to pathogens
If the first line of defence fails the next line of defence is phagocytosis...
Phagocytes(type of white blood cell) ingest and destroy the pathogen by a process called phagocytosis.
Specific response.
The primary immune response confers(grants) immunity. Immunity is the ability of organisms to resist
infection by protecting against disease causing microorganisms or their toxins that invade bodies.
^^involves recognition of foreign material(antigens). The presence of antigen triggers an immune
response.
• Passive immunity: produced by the introduction of antibodies into individuals from an outside
source. Immunity is acquired immediately.
• Active immunity: produced by stimulating the production of antibodies by the individuals own
immune system. Immunity takes time to develop. Generally long lasting but direct contact with
pathogen/antigen is required.
Antigenic variability: Pathogen may mutate frequently so antigens change suddenly rather than
gradually.
Antigen: A protein found on the surface of an organism that is recognised as non-self by the immune
system and stimulates an immune response.
Antibody: proteins with specific binding sites synthesised by B plasma cells
Agglutination: The clumping together of cells or particles caused by antibodies which assists
phagocytosis.
Helper T cell: A type of T cell in the immune system that stimulates cytotoxic T cells, B cells and
phagocytes.
Herd immunity: A type of disease immunity that occurs when a large proportion of a population are
vaccinated against a disease which prevents the spread of the disease to unvaccinated individuals.
Human Immunodeficiency Virus (HIV): A virus that attacks T cells in the immune system and can lead to
AIDS (acquired immune deficiency syndrome).
Immunity: protection against disease provided by the immune system
Immune response:
Lysosomes: Membrane-bound vesicles found in the cytoplasm that contain a hydrolytic enzyme called
lysozyme.
Lysozymes: digestive enzymes
(Non-specific immunity)
The body’s first line of defence is to form physical and chemical barriers to entry. This response is
immediate and the same for all pathogens. e.g skin provides a physical barrier to pathogens
If the first line of defence fails the next line of defence is phagocytosis...
Phagocytes(type of white blood cell) ingest and destroy the pathogen by a process called phagocytosis.
Specific response.
The primary immune response confers(grants) immunity. Immunity is the ability of organisms to resist
infection by protecting against disease causing microorganisms or their toxins that invade bodies.
^^involves recognition of foreign material(antigens). The presence of antigen triggers an immune
response.
• Passive immunity: produced by the introduction of antibodies into individuals from an outside
source. Immunity is acquired immediately.
• Active immunity: produced by stimulating the production of antibodies by the individuals own
immune system. Immunity takes time to develop. Generally long lasting but direct contact with
pathogen/antigen is required.
Antigenic variability: Pathogen may mutate frequently so antigens change suddenly rather than
gradually.
