2.4 Immunology Flashcards
pathogen
a micro-organism that has the potential to cause disease
ways that pathogens can cause disease
kill body cells
releasing toxins that damage cells
what is an antigen made from
proteins
antigen
a molecule (protein) which causes an immune response resulting in the prodcution of specific antibody
self antigen
a molecule (protein) found in the cell surface membrane of your own body cells which allows immune system to recognise the cell as itself
four types of pathogen
bacteria
viruses
fungi
protozoa
non specific immune response
phagocytosis
steps of phagocytosis
- phagocyte engulfs pathogen
- pathogen in vesicle (phagosome)
- lysosome containg hydrolytic enzymes fuses with vesicle (phagolysosome)
- pathogen hydrolysed and digested
5.waste released and antigens presented on cell surface
specific immune responses
- cell mediated response (producing T-lympocytes)
- humoral response (B lymphocytes)
T lymphocytes
associated with cell mediated immmunity (immunity involving body cells)
B lymphocytes
associated with humoral response and produce antibodies
roles of T cells
stimulate cytotoxic T cells to divide
stimultae further phagocytosis
stimulate B cells to divide
develop into memory T cells to prevent future infection
cytotoxic T cells
seek out antigens on suface of antigen presenting cells
they bind to the invaded cell and secrete toxic substance to kill cell
antigen presenting cells (APC’s)
either phagocytes or cells that have been invaded
once phagocytosis has happened pathogens antigens are presented on cell membrane of phagocyte
T cells then respond to the cell which is presenting the antigens
cell mediated immunity steps
- pathogens invade body cells or are taken in by phagocytosis
- APC’s present pathogens antigen on its own cell surface
- T helper cells have receptors which fit to presented antigens this stimulates t cells to divide by mitosis
- T cells either:
- stimulate cytotoxic T cells
- stimulate further phagocytosis
- stimulate B cells to divide
- develop into memory T cells to prevent future infection
steps of humoral response
- T helper cellls activate the complementary B cels
- B cells divide by mitosis
- makes memory cells for future infections
- makes plasma cells which make antibodies
- antibodies bind to antigen on pathogen to destroy them
passive immunity
immunity from being given antibodies made by a different organism
natural passive immunity
a baby becomes immmune to antibodies it recieves from mother through placenta and breast milk
artifical passive immunity
when given antibodies from someone else eg blood donation
active immunity
immunity you get from your own immune system making its own antibodies aftre being stimulated by an antigen
natural active immunity
when you become immune after catching a disease
artificial active immunity
when you become immune after being given a vaccination
what is antigenetic variability
antigens can mutate and change shape
memory cells therefore cannot recognise the pathogen
antibodies no longer complementary to receptors and a secondary response cannot be initiated
monoclonal antibodies
made from the same B cell
all the same
and all complemenary to the same antigen
what is a vaccination
an injection of a dead or weakend pathogen which initiated an immune response and produces memory cells
what does HIV do
attacks the bodies immune system.
what is AIDS
a person is considered to have AIDS when the immune system is so weak it can no longer fight off diseases
