5 cell recognition and immune system Flashcards
state 2 ways pathogens can cause harm
pathogens can produce toxins that damage tissue
pathogens can replicate inside and destroy host cells
what can the molecules on the plasma cell surface membrane identify?
pathogens
abnormal body cells
toxins
cells from other organisms of the same species
what is an antigen?
an antigen is a molecule that stimulates an immune response that results in the production of a specific antibody
what happens if antigens on a cell are not recognised?
the body will treat the cell as non self and initiate an immune response. this will destruct the cell
what are phagocytes?
groups of white blood cell
what does a phagocyte do?
- pathogen engulfed by phagocyte
- pathogen enters the cytoplasm of the phagocyte in a vesicle which is now called a phagosome
- lysosomes fuse with phagosome releasing lysozymes
- lysozymes hydrolyse pathogen
- waste materials are released by exocytosis and antigens are presented on the membrane making the pathogen an APC
what type of process is phagocytosis?
non specific.
what does non specific mean?
works the same for any cell that displays a non self antigen
why does phagocytosis not work all the time?
non specific so would take too long to destroy all pathogens in an infection resulting in damage to tissues and organs
what is a specific response?
specific to certain antigens or pathogens that have been recognised as non self
what are the 2 types of specific immunity?
cell mediated
humoural
what are the 3 stages of the cell mediated response?
- antigen presenting
- clonal selection
- role of t cells
describe antigen presenting stage of cellular response.
TH cells respond directly to specific pathogen or respond to APC (from phagocytosis) that presents specifically complementary antigen
explain clonal selection as a part of the cellular response
- specific TH cell binds to presented antigen via its complementary receptor
- TH cell activated and clones by mitosis (produces cells with complementary receptors to the antigen)
what is the role of a TH cell?
- binds to antigen on presenting cell
- releases cytokines that attract phagocytes and activate Tc cell
- activates specifically complementary B cell
- form memory Th cells
what is a Tc cell?
cytotoxic killer cell
what is the role of a Tc cell?
- locate and destroy infected body cell
- binds to APC
- releases perforin which created holes in the cell surface membrane
how are B cells activated in the humoral response?
- specific TH cell binds to APC and locates and activates a specifically complementary B cell
- TH cell releases cytokine that signals the B cell to clone by mitosis
what happens when the B cell clones by mitosis?
B cell differentiates into
plasma cell or memory B cell
what do plasma cells do?
produce and secrete vast quantities of specific antibodies into blood plasma