cell recognition and immune system - 2 Flashcards
topic 2
antigen definition
molecule that triggers an immune response by lymphocytes
pathogen definition
organisms that cause disease
phagocyte definition
type of white blood cell that carries out phagocytosis
how do phagocytes work (5 points)
- phagocytes recognises foreign antigens
- cytoplasm of phagocyte moves around the pathogen and engulfs it
- pathogen is in a phagocytic vacuole in the cytoplasm of the phagocyte
- lysosome fuses with phagocytic vacuole and breaks down the pathogen
- phagocyte presents pathogen’s antigens - sticks the antigens on its surface to activate immune system cells
2 types of T-cells
cytotoxic cells
helper cells
word where pathogens clump together
agglutination
antibody definition
protein produced by lymphocytes in response to the presence of the appropriate antigen
antigens enable the immune system to identity….
- pathogens
- abnormal body cells
- toxins
- cells from other organisms of the same species
where are phagocytes made
bone marrow
what do neutrophils do
engulf and digest pathogens
what do macrophages do
punch small holes in pathogen to mark the cell for destruction by neutrophils
process of phagocytosis (4)
- pathogen is recognised as ‘non-cell’ due to antigens. phagocyte attaches to pathogen
- phagocyte engulfs the pathogen and forms and phagosome
- phagosome and lysosome fuse together, digestive enzymes break down pathogen and hydrolyse it
- harmless products are removed from the cell by exocytosis
APC meaning
antigen presenting cell
APC description of function
have a pathogenic antigen on their surface signals T-cells
what does the cellular immune response consist of
T cells target pathogens within cells
what do T helper cells do
stimulate and recruit more cells to assist in the immune response
what synthesises antibodies and in response to what
B cells in response to antigens from a pathogens surface
why is it important antibodies can change shape
so they can bind to multiple antibodies as it has an induced fit model
why don’t vaccinations full eliminate diseases
different strains may form
not available to everyone
expensive
done on a large scale to achieve herd immunity
what does AIDS stand for
acquired immunodeficiency syndrome
HIV structure
core- RNA and proteins, reverse transcriptase
capsid- outer protein coat
envelope- made from membrane taken from host cell’s membrane
protein attachments- help the virus attach to host’s T helper cells
simple description of how HIV replicates (4)
- virus attaches
- genes copied
- replication
- released
4 ways HIV is spread
- unprotected sex with someone who is HIV positive
- blood transfusions
- sharing needles
- breast feeding
3 ways the immune system can respond to antigens
- lysosomes break down foreign cells
- phagocytosis of the foreign cells
- production of antibodies that bind to antigens and inhibit the functioning of the foreign cells
