Immune System Topic 2 Flashcards
(28 cards)
what cells can non-self cells identify
pathogens
cancer cells/abnormal
cells from other organisms
toxins
what is an antigen
protein that stimulates an immune response
what is antigenic variability
if a mutation in the gene codes for the antigen, then the shape of the antigen will change so any previous immunity is no longer effective as the memory cells will not recognize / have a memory of the old antigen shape
the influenza virus mutates and changes it antigens very quickly this is why a new flu vaccine has to be created each year
because of antigenic variability
what happens when a pathogen get past the chemical and physical barriers
white blood cells will become a defence mechanism
is phagocytosis a specific or non specific response
non specific
what is phagocytosis
phagocytes move towards the pathogen and attach to it
phagocyte enguls pathogen via receptors
phagosome is formed
phagosome fuses with lysosome
lysosomez digest the pathogen into soluble materials
pathogen becomes an antigen presenting cell
what are lymphocytes and where are they made
white blood cells
bone marrow
where do t cells mature
thymus
what is an antigen presenting cell
give an example
any cell that presents a non self antigen on their surface
cancer cells
macrophage
explain the process of the cell mediated response
antigen are displayed on the cell surface once the pathogen are destroyed
helper T cells have receptors on their surface which can attach to the antigens on the antigen presenting cell
helper t cell activated to divide by mitosis to make large number of T helper cell clones
these cloned helper t cells can differentiate into:
memory cells
cytotoxic T cells
B cells
what is the purpose of the cell mediated response
to produce as many T-helper cells as possible
what can the T cells differentiate into
cytotoxic cells
B cells
memory cells
what is the function of cytotoxic cells (protein released)
destroy the abnormal cells by releasing a protein called perforin
what protein do cytotoxic cells release
perforin it destroys abnormal/infected cells
where do B cells mature
bone marrow
what happens when a B cell collides with a helper T cell
B cells go through clonal expansion
B cells undergo mitosis which can differentiate into plasma cells or memory B cells
plasma cells make antibodies
structure of antibody
quaternary protein
4 polypeptide chains
what is the function of the variable region
they form the antigen binding site
what is the function of the constant region
determines the mechanism of an action, e.g. such as binding to phagocytes
what happens in agglutination
antibodies are clumped together
this carries out signals for phagocytes to come and carry out phagocytosis
antibodies will mark the pathogens to carry out phagocytosis
what is passive immunity
where the pathogen does not enter the body
no long term immunity
e.g. antibodies passed to a fetus through the placenta
what is active immunity and what are the types
immunity created by your own immune system
artificial active immunity e.g. vaccine
natural e.g. antibodies and memory cells
explain the process of vaccination
inactive form of pathogen introduced to body / injected
exposure to the antigen causes
B cells go through clonal expansion and differentiation
B cells undergo mitosis
they differentiate into plasma cells or memory B cells
plasma cells make antibodies
B memory cells can divide rapidly into plasma cells when reinfected to make large number of antibodies quickly
what is herd immunity
when most of the population are vaccinated which provides protection to people who are not vaccinated
