12.8 Immunology Flashcards
state 2 ways that pathogens cause harm / disease
- pathogens can produce toxins which can directly damage tissue
- pathogens can sometimes replicate inside and destroy host cells
each type of cell has … on its plasma cell-surface membrane that identify it
specific molecules
these molecules include proteins and enable the immune system to identify:
- pathogens
- cells from other organisms of the same species
- abnormal body cells (cancer cells from on body)
- toxins (often secreted by pathogenic bacteria)
antigen definition
a molecule (usually a protein) that stimulates an immune response that results in the production of a specific antibody (antibody generator)
own cells =
SELF
foreign cells / pathogens =
NON SELF
the surface of all own cells (self) and foreign cells / pathogens (non self) are covered in…
specifically shaped antigens
these antigens help identify…
each particular type of cell to the host organism
what happens if the antigens are not recognised
the body will treat that cell / pathogen as non self and initiate an immune response which will lead to the destruction of the cell / pathogen / protein.
examples of antigens
glycoproteins and glycolipids
what are phagocytes
groups of white blood cells which can distinguish between cells which do or do not display the self-antigens
the process phagocytes undergo is called
phagocytosis
phagocytosis process
- pathogen is engulfed by the phagocyte
- engulfed pathogen enters the cytoplasm of the phagocyte in a vesicle which is now called a phagosome
- lysosomes fuse with phagosome releasing hydrolytic digestive enzymes (lysozymes)
- lysosome enzymes hydrolyse the pathogen
- waste materials are released from the cell by exocytosis and antigens presented on the cell surface membrane and the phagocyte becomes an antigen presenting cell (APC)
is phagocytosis specific or non-specific
non-specific (works the same for any pathogen that displays a non-self antigen)
why is phagocytosis not used in the event of an infection
- it would take far too long to destroy all the invading pathogens
- may result in damage to tissues and organs
name the specific cellular responses
- response of T lymphocytes (cell-mediated immunity -> primary response)
- action of T cells
- activation of B cells (humoral response -> primary response)
2 stages in response of T lymphocytes (cell-mediated immunity -> primary response)
- antigen presenting
- clonal selection
antigen presenting process in response of T lymphocytes (cell-mediated immunity -> primary response)
- specific TH cells can respond directly to a specific pathogen or its antigens / respond to APC that presents the specifically complementary antigen to their receptors
- APC presents the pathogen’s antigen on its cell surface membrane
clonal selection process in response of T lymphocytes (cell-mediated immunity -> primary response)
- a specific TH cell binds to presented antigen via its complementary receptor
- TH cell is activated and clones to produce many TH cells with complementary receptors to the antigen
summary of the process: response of T lymphocytes (cell-mediated immunity -> primary response)
- phagocyte engulfs & hydrolyses the pathogen and presents the antigen on its cell surface membrane
- TH cell with specific receptor molecule binds to presented antigen
- once TH cell binds to the presented antigen it is activated. it then rapidly clones by mitosis
roles of the TH cell
- specific TH cell binds to the APC
- release cytokines that attract phagocytes to the area of infection
- release cytokines that activate TC cell (cytotoxic killer)
- activates a specifically complementary B cell
- form memory TH cell
roles of the TC cell (cytotoxic killer)
- locate and destroys infected body cells that present the corrected antigen
- binds to APC
- releases perforin (protein) which creates holes in the cell surface membrane which destroys the APC
what is the humoral response
involves the activation of B cells to produce antibodies. B cells must be stimulated by their complementary TH cell by the release of cytokines.