BIO CHAP7/8 IMMIUNITY

UNIT4 AOS1

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

Self-antigens

located on the surface of cells, mark the cells of an organism as ‘self’ so that the immune system doesn’t attack them

Are MHC markers self or non self antigens

self antigens

MHC 1

located on the surface of cells, mark the cells of an organism as ‘self’ so that the immune system doesn’t attack them

MHC 2

expressed on antigenpresenting 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

What is an examples of an autoimmune disease?

lupus

What are the two categorises of pathogens

cellular and non cellular

Cellular pathogens

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

hyphae

 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

examples of cellular pathogens

Bacteria, fungi, worms, protozoa

examples of non cellular pathogens

viruses, prions

innate immune system 

a component of the immune system that is composed of generalised and non-specific defences and/or responses to pathogens. Also known as the non-specific immune system

first line of defence

a component of the innate immune system characterised by the presence of physical, chemical, and microbiological barriers to keep pathogens out of the host organism

second line of defence

a component of the innate immune system characterised by the nonspecific response to injury and/or pathogens by a variety of cells and molecules

non-specific

describes a component of the immune system that responds the same way to all pathogens

microbiological barrier eg

normal flora on skin, in the gastrointestinal tract, and vagina

physical barriers eg

mucus secretions and cilia_, intact skin

chemical barriers

stomach acid, lysozymes and digestive enzymes

second line of defence

a component of the innate immune system characterised by the nonspecific and immediate response to injury and pathogens by a variety of cells and molecules

leukocytes

a group of blood cells responsible for protecting the body against pathogens and foreign material. Also known as white blood cells

phagocyte

a group of leukocytes responsible for the endocytosis and destruction of pathogens, foreign material, and cell debris

neutrophil 

the most common type of leukocyte in the body. Engages in phagocytosis of pathogens and foreign material, as well as the release of cytokines

macrophages

A type of leukocyte found throughout the body that engages in ohagocytosis and antigen presentation.

dendritic cell

A type of leukocyte that engages in phagocytosis and antigen presentation.

cytokines

A signalling molecule released by cells which aids in communication between immune cells and helps protect against pathogens.

mast cell

a type of leukocyte responsible for releasing histamine during allergic and inflammatory responses

degranulation

the release of granule contents from a cell

histamine

a molecule released by mast cells that plays a key role in inflammation

killer inhibitory receptor

examines the surface of cells for MHC 1 markers

Killer activation receptor

binds to certain molecules which appear on cells undergoing cellular stress.

Why might a killer inhibitory receptor override the killer activation signal to prevent cell death?

if the killer inhibitory receptor detects a sufficient number of MHC 1 markers

When is cell death initiated in infected cells/abnormal cells?

when there are missing MHC 1 marker. That is when the killer activation receptor is activated and the killer inhibitory receptor is unable to bind to a sufficient number of MHC class 1 markers.

histamine

a molecule released by mast cells that plays a key role in inflammation

inflammatory response

a series of biochemical events that occur in the body as a result of infection and/or trauma. Characterised by swelling, redness, pain, and heat in the affected tissue

eosinophil

a large granular leukocyte responsible for the release of toxic chemical mediators

interferon

a cytokine released by virally infected cells that increases the viral resistance of neighbouring uninfected cells

complement proteins

a number of different types of proteins found in the blood that opsonise, cause lysis, and attract phagocytes to invading pathogens

what are the Non-cellular components of the second line of defence?

interferons, complement proteins, and the initiation of a fever.

complement cascade 

a complex sequence of events which occurs after the activation of complement proteins

opsonisation

the mechanism by which complement proteins attach to the surface of pathogens, making them easier to phagocytose

chemotaxis

the attraction of phagocytes towards a pathogen

lysis

the disintegration or rupturing of a cell

T lymphocyte

a type of lymphocyte that plays an important role in cell-mediated immunity. It differentiates into cytotoxic T cells, T memory cells, and T helper cells

T helper cell (Th)

type of differentiated T lymphocyte that supports the functioning of a number of different immune cells, including the cloning and differentiation of selected T and B cells

antigen-presenting cell

a subgroup of phagocytes that display the antigens from consumed pathogens on their surface and interact with the adaptive immune system

lymphatic system

a large network of vessels and tissues throughout the body that form an important component of both the circulatory and immune systems

lymph node

 a small secondary lymphoid tissue of the lymphatic system where antigen-presenting cells activate the adaptive immune system

humoral immunity

an adaptive immune response in which extracellular pathogens are targeted by specific antibodies produced by plasma cells. Also known as B cell immunity

cell-mediated immunity

an adaptive immune response in which infected or abnormal cells are destroyed by cytotoxic T cells. Also known as T cell immunity

How does The activation of these B lymphocytes occur

interaction with pathogenic antigens and T helper cells.

clonal selection

the process in which B and T cells encounter an antigen that matches their antigenbinding site, and then generate many copies of themselves. Also known as clonal selection theory

clonal expansion

the process in which many copies of a lymphocyte are generated

differentiation

he process in which cells develop specialised characteristics, typically transforming them from one cell type to another more specialised cell type

B memory cell

a differentiated B lymphocyte that is responsible for providing long-lasting immunological memory of an antigen

plasma cell 

a differentiated B lymphocyte that is responsible for the generation and secretion of antibodies during the humoral response

what does the structure of an antibody include

constant region, variable region, antigen, antigen binding site

types of antibodies

IgA, IgD, IgE, IgG, IgM

IgG

Most common antibody found in the body. Able to cross the placenta and travel to the foetus.

IgA

Found in mucus, breast milk, and saliva.

IgD

Important for the activation of other immune cells

IgE

Protects against parasitic worms. Also responsible for allergic reactions.

IgM

The first type of antibody produced by plasma cells in response to an infection.

Neutralisation

Antibodies can block the sites of pathogens that are used to attack host cells (e.g. the site used by a virus to enter a cell) and can block the active sites of toxins.

Agglutination

Antibodies can bind together with antigens on two separate pathogens, forming large antigen-antibody complexes. This makes it easier for phagocytes to recognise the pathogens as foreign bodies and destroy them

Immobilisation

Antibodies can also restrict the movement of pathogens around the body through the formation of large antigenantibody complexes

Opsonisation

Antibodies can bind directly to the surface of a pathogen to make it easier to phagocytose.

Activation of complement proteins

Antibodies attached to the surface of pathogens can facilitate the actions of complement proteins, including the formation of membrane attack complexes (MACs).

T memory cell

 a differentiated T lymphocyte that is responsible for providing long-lasting immunological memory

apoptosis

the controlled death of cells in the body. Also known as programmed cell death

circulatory system

a collection of tissues and organs involved in the transportation of substances around the body. Composed of the lymphatic and cardiovascular systems

lymphatic system

a large network of vessels and tissues throughout the body that form an important component of both the circulatory and immune systems

secondary lymphoid tissue

components of the lymphatic system that are responsible for the maintenance of mature lymphocytes and the activation of the adaptive immune response. Includes lymph nodes and the spleen

primary lymphoid tissue 

components of the lymphatic system that are responsible for the production and maturation of lymphocytes. Includes bone marrow and the thymus

Functions of the lymphatic system

transportation of antigen-presenting cells to secondary lymphoid tissues for antigen recognition and initiation of the adaptive immune response, production of leukocytes, removal of fluid from tissues, absorption of fatty acids from the digestive system.

Where are mast cells mostly located

connective tissue, surrounding blood vessels

What do mast cells release

histamine

in the innate immune response, what is the result of mast cells releasing histamine?

Blood vessels dilate, become permeable and leaky., attracts phagocytes

what type of cell wont you find MHC 1 markers?

red blood cells as they don’t have a nucleus

What cells are MHC II marker located at?

Dendritic cells, macrophages, B lymphocytes

natural immunity

protection against a disease formed without medical intervention

artificial immunity 

protection against a disease formed as a result of medical intervention. Also known as induced immunity

active immunity

protection against disease created by antibodies and memory cells formed by a person’s own adaptive immune system

passive immunity

protection against a disease created by antibodies from an external source.

natural active immunity

protection against disease created by antibodies and memory cells produced by an individual’s own immune system without medical intervention.

natural passive immunity

protection against a disease created by antibodies from an external non-medical source.

examples of natural active immunity