VCE Biology Unit 4 AOS 1 Antigens and immunity

Antigen

Substances that can stimulate an immune response in the body.

Self-antigen

Antigens produced by a person's own body that are tolerated by the immune system due to MHC 1 markers.

MHC I

molecules found on every body cell that presents antigen; signals cytotoxic T to destroy

MHC II

expressed on the surface of APCs (macrophages, dendritic cells, B cells) and functions by presenting non self antigens . Antigen is taken into the body by phagocytosis or endocytosis and is loaded onto MHC II .

Non-self antigen

Antigens that do not belong to an organism's own cells and are attacked by the immune system.

Allergen

A type of antigen that produces an abnormally vigorous immune response in which the immune system fights off a perceived threat that would otherwise be harmless to the body.

Infection

Occurs when pathogenic bacteria, viruses or other microbes gain entry to the human body and begin to multiply.

Disease

A condition where part or all of an organism's normal physiological function is disturbed.

Infectious disease

Diseases caused by pathogenic agents, that can be passed from one organism to another.

Virulence

The ability of a pathogen to cause disease.

Incubation period

The time between the entry of the infectious pathogen and the appearance of the first symptoms.

Microbe

a microorganism, especially a bacterium causing disease or fermentation

Pathogen

A cellular or non-cellular agent of disease

Host

An organism in which a pathogen parasitically lives.

Vector

An organism that transmits a pathogen from one host to another.

Cellular pathogen

A pathogen that is made up of cells

Non-cellular pathogen

A pathogen that is not made up of cells

Bacteria

Microscopic prokaryotic cellular pathogens without membrane bound organelles.

Viruses

Non- cellular pathogens composed of a nucleic acid core and a protein coat.

Prions

Non-cellular pathogens that are abnormal forms of normal cell proteins.

Lysozyme

An enzyme in mammals that destroys bacterial cell walls.

found in sweat, tears and saliva

Innate immune response

A quick, general and nonspecific immune response.

Phagocyte

A white blood cell that destroys pathogens by engulfing them through endocytosis and digesting them with the lysozyme released by lysosomes.

Neutrophil

A type of phagocyte that engulfs invading microbes and contributes to the nonspecific defences of the body against disease.

Macrophage

Large phagocyte that removes bacteria, foreign particles and dead cells.

Dendritic cell

Antigen-presenting cells that process engulfed fragments and display the foreign antigens on their surface.

Natural killer cell

A type of white blood cell (lymphocyte) that can kill tumour cells and virus-infected cells by releasing cytotoxic granules.

Degranulation

The release of anti-microbial and toxic molecules into a target cell, from membrane-bound granules stored in the cytoplasm of the natural killer cells.

Inflammatory response

An early and short-term response of the body to infection, that is localised around the site of entry of pathogens, so that the local area becomes red, swollen, hot and often painful.

Mast cells

Cells that release histamine to promote inflammation.

Complement

Dissolved proteins in the blood plasma

Complement proteins

proteins in blood that help destroy pathogens

Opsonisation

Coating of bacteria with complement so that phagocytes are attracted and can bind them.

Membrane-attack complex

Complex that forms on the surface of a pathogen, creating a pore and allowing fluid to enter the cell, resulting in lysis.

Lymphatic system

Consists of a network of thin-walled lymphatic vessels containing lymph that reaches all tissues of the body and interconnects the lymphoid organs.

Lymph

A colourless tissue fluid containing white blood cells.

Leucocytes

white blood cells

Primary lymphoid tissue

Bone marrow and thymus

Secondary lymphoid tissue

Lymph nodes and spleen

Lymph nodes

Bean-shaped filters that cluster along the lymphatic vessels of the body.

The sites where any new foreign antigens meet and activate B and T cells, and where the immune response occurs

Adaptive immune response

Initiated after innate immunity fails to check an infection, when antibodies respond to specific antigens.

Antibody

A quaternary Y-shaped protein produced by a B plasma cell in response to and counteracting a specific antigen.

Lymphocyte

A type of white blood cell that makes antibodies to fight off infections, as part of adaptive immunity.

Cell mediated immunity

An immune response that does not involve antibodies, but rather involves the activation of phagocytes, antigen-specific T-lymphocytes, and the release of various cytokines in response to an intracellular antigen.

Interleukins

proteins (cytokines) that stimulate the growth of B and T lymphocytes

Humoral immune response

Immune response mediated by antibodies

Memory cells

Lymphocytes that remember a specific antigen and produce a much quicker immune response if that same pathogen infects the body.

Plasma cells

B lymphocytes that produce antibodies

Clonal selection

The process by which an antigen selectively binds to and activates only those lymphocytes bearing receptors specific for the antigen.

Clonal expansion

The rapid multiplication of lymphocytes that have been bound to by their specific antigen, producing many identical cells with identical antigen-binding receptors.

Helper T cells

Lymphocytes that activate cytotoxic T cells, B cells, and macrophages.

Cytotoxic T cells

Lymphocytes that induce apoptosis in virus infected body cells.

B cells

Lymphocytes that produce antibodies against extracellular pathogens.

Agglutination

Clumping of pathogens

Extracellular pathogen

a pathogen that grows and multiplies in the space and fluids surrounding the cells- bacteria

Intracellular pathogen

a pathogen that lives inside of cells- virus

Interferon

Protein produced by T cells in response to being infected by a virus; helps other cells resist the virus.

Immunity

Resistance to infectious disease

Acquired immunity

Specific immunity that is present only after exposure to a pathogen.

Active immunity

Antibodies are produced by a person's own adaptive immune system.

Passive immunity

Antibodies are acquired by a person from an external source.

Natural immunity

Immunity occurs naturally, without deliberate intervention.

Artificial immunity

Immunity is induced through a deliberate intervention.

Natural active immunity

The production of antibodies by the body in response to a particular pathogen that has invaded the body.

Natural passive immunity

The receiving of antibodies by being passed from one person to another.

- mother to baby

Artificial active immunity

The deliberate introduction of a disabled pathogen or its toxin into the body, causing antibodies to be produced for that specific pathogen.

Artificial passive immunity

The deliberate injection of antibodies into the body to fight a specific pathogen.

Vaccine

A substance used to stimulate the production of antibodies and provide immunity against a particular disease.

Attenuation

The weakening of the virulence of a pathogen, preventing its ability to reproduce inside the body and cause the disease.

Primary immune response

Immune response the first time the body is exposed to a particular antigen.

Secondary immune response

Immune response after the body has already been exposed to a specific antigen. Response is faster, of greater magnitude, and more prolonged.

Herd immunity

protection from a disease due to immunity in most of a population

Autoimmune disease

A disease in which the immune system attacks the organism's own cells.

Autoantibodies

Antibodies that attack the body's own cells

Multiple sclerosis

An autoimmune disease that results from antibodies attacking the myelin sheath that insulates nerve fibres in the brain and spinal cord.

Immunodeficiency

A disorder in which the immune system is unable to protect against pathogens.

HIV

A virus that targets the body's T helper cells, disabling the body's immune defences and taking over these cells to produce more copies of the virus.

Allergic reaction

An abnormally excessive immune response to a substance in the environment that are harmless to most people.

Sensitisation

Producing IgE antibodies so that the next exposure to the allergen will cause an allergic response.

Primed mast cells

Mast cells coated in IgE antibodies

Hayfever

allergy to plants and pollen

Anaphylactic shock

Severe allergic reaction

Monoclonal antibodies

Specially designed sets of antibodies, with every antibody in the set binding to the same antigen, primarily used to treat cancer.

Naked monoclonal antibodies

Monoclonal antibodies with no other molecules attached to them

Conjugated monoclonal antibodies

Monoclonal antibodies with an additional group attached