Bio unit 4 aos 1

Innate immune system

the non specific, natural immunity that you one is born with

adaptive immune system

The specific, acquired immunity that is developed over time

Aim of the first line of defense

to keep pathogens out of your body

agranulocytes

doesn’t contain ganules

phagocyte

destroys pathogens and foreign materials by englufing them

Antigen presentation

process where some phagocytic cells display the antigens of a consumed pathogen on their surface

Macrophage

A phagocyte and APC formed from a monocyte that lives in tissues and destroys pathogens, dead cells and debris by phagocytosis

Dendritic cell

A phagocyte and APC formed from a monocyte that captures antigens in tissues and activates and regulates the adaptive immune response.

Neutrophil

A phagocyte and granulocyte that is formed from a monocyte and is the most abundant white blood cell that circulates in the blood, is first to respond to infection, and destroys pathogens by phagocytosis and releasing antimicrobial granules.

Eosinophil

A granulocyte formed from a monocyte that destroys large pathogens by releasing toxic enzymes that damage their cell membranes.

Phagocytosis

The process of destroying pathogens and foreign material by engulfing them

Antigen Presentation

Process where some phagocytic cells display the antigens of a consumed patogen on their surface.

Granulocytes

contains granules (enzymes that digest pathogens) released during an immune response.

Leucocytes

General name for white blood cells made in the bone marrow that circulate in the blood and move into body tissues to fight infection

Mast Cell

A granulocyte found in tissues that releases histamine during allergic and inflammitory responses, causing vasodilation and attracting phagocytes,

Natural Killer Cell

A non specific lymphocyte that detects and destroys infected or cancerous body cells by releasing perforin and granzymes, causing apoptosis.

Cytokines

Small signalling molecules released by white leukocytes or infected cells that help coordinate and regulate the immune response

Interferons

A type of cytokine released by virus infected cells that helps prevent viruses from spreading by increasing the resistance of nearby healthy cells

Compliment proteins

Inactive plasma proteins that become activated by pathogens and help destroy them through opsonisatoin, chemotaxis and lysis

Opsonisation

Compliment proteins attach to the surface of the pathogen (making them easier to phagocytose as they are more identifiable)

Chemotaxis

Compliment proteins attract phagocytes towards a pathogen

Lysis

Compliment proteins can join together on the surface of a pathogen to form a membrane attack complex (MAC). Leads to rupturing and disintegration of pathogen.

Histamine

An organic compound released by mast cells that triggers the allergic and inflammatory response causing vasodilation.

Inflammatory Response

A non specific immune response that increases blood flow and capillary permeability, allowing white blood cells to reach infected tissues. This causes redness, heat, swelling, pain and sometimes fever to help fight pathogens.

Inflammatory Response Steps: Initiation

Pathogens activate macrophages and mast cells which release cytokines and histamine to start the inflammatory response.

Inflammatory response steps: Vasodilation

Histamine causes blood vessels to widen and become more permeable, increasing blood flow causing redness, heat and swelling

Inflammatory Response Steps: Migration

Phagocytes and compliment proteins move from the blood to the infected tissue to help destroy pathogens.

Perforin

A protein released by natural killer cells that form pores in the target cell membranes, allowing granzymes to enter and trigger apoptosis.

Antigen Presenting Cells (APC)

Phagocytes that display pathogen antigens on their surface and travel to lymph nodes to activate complimentary T helper cells, linking the innate and adaptive immune systems

MHC Class I markers

Antigens are found on the surfaces of almost all human cells, allowing natural killer cells and cytotoxic t cells to identify infected or abnormal cells

MHC Class II Markers

Antigens are only found on the macrophages, dendritic cells and B cells of the immune system, activating T cells to start the adaptive immune response

Clonal Selection

Process wherby a lymphocyte encounters a specific antigen, identifying the cell for expansion as part tof the adaptive immune system

Proliferation

rapid growth and reproduction of cells

Differentiation

When less specialised cells divide into more specialised cells

T cells

Lymphocytes produced in the bone marrow that mature in the thymus and are activated in the lymph nodes by specific antigens, becoming memory T cells or effector T cells.

T helper cells (Cell mediated immunity)

A lymphocyte that is activated by APC’s and releases cytokines to coordinate immune responses by activating B cells, cytotoxic T cells, and macrophages. It is a specific response.

Humoral immunity

An adaptive immune response in which extracellular pathogens are targeted by specific antibodies produced by plasma cells

Cell mediated immunity

involves various actions of T cells that remove infected cells (from intercellular pathogens) or damaged cells (no direct pathogen contact)

Cytotoxic T cell (Cell mediated immunity)

A type of lymphocyte that destroys infected or abnormal cells by recognising specific antigens and releasing perforin and granzymes to trigger apoptosis.

Regulatory T cells (Cell Mediated immunity)

A type of T lymphocyte that suppresses immune responses by reducing cytokine production, preventing overactivation and autoimmune reactions.

B cells (humoral immunity)

Makes antibodies and is specific to an anttigen

What are the steps in Specific B cell Activation?

A B cell recognises the specific antigen, processes it, and presents it on an MHC Class II Marker to an activated T helper cell

How does a T helper cell activate a B cell?

The T helper cell recognises the antigen on the B cell and releases cytokines that stimulate B cell proliferation and differentuation

What is clonal expansion in B cells?

The rapod diviion of B cells to produce many identical cells with the same antigen specificity.

What do activated B cells differentiate into and what are their functions?

They become plasma cells, which produce antobodies, and memory B cells which provide long term immunity.

Memory B cell

Long lived B cells that provide immunological memory and rapidly differentiate into anttibody - producing cells when the same pathogen is encountered again.

Plasma B cells

Short lived B cells that produce and secrete large amounts of antibodies to provide short term protection against pathogens.

Structure of antibodies

Y-shaped proteins made of 2 heavy and 2 light polypeptide chains, with constant regions and variable regions that determine antigen specificity. Each antibody has 2 antigen binding sites.

Precipitation reaction

soluble pathogens become insoluble

Agglutination

antibodies