defence mechanisms and phagocytosis Flashcards
whats the function of an immune system?
a complex defence mechanism designed to protect from number of threats (pathogens, toxins, abnormal body cells, cells from other individuals - e.g. transplants)
what is a pathogen?
a microorganism or infectious agent that causes communicable disease
what is a cellular pathogen?
parasites (helmithes - tapeworm), protoza (plasmodia/ malaria), fungi (tinea - athletes foot), prokaryote (bacteria - leprosy)
what is a acellular pathogen (non-living) ?
virus ( e.g. HIV/ aids), prion (CJD)
what do membranes of all cells contain?
glycolipids and glycoproteins called antigens
what can antigens be identified by the immune system as?
either self or non-self
are antigens specific to each individual?
YES
what happens once the immune system has identified a non-self antigen?
it will innitiate an immune response
what happens once the immune system has identified a non-self antigen?
it will innitiate an immune response
what are the two immune responses and wgat do they do?
non-specific (innate) responses (they do barrier defences and phagocytosis), specific (adaptive) response (they do cell-mediated responses and humoral responses)
what are barrier defences for the body?
barrier defences are the first line of defence against a pathogen
what else do barrier defences do?
block a pathogen entry into the body or destroy and inactivate those that get in
what are the type of barrier defences?
- digestive enzyme
- skin
- lysosomes
what is the process of phagocytosis?
process carried by the white blood cell called a phagocyte
whats the first step of phagocytosis?
phagocytes engulf and digest foreign cells or particles
whats the second step of phagocytosis?
pathogen is engulfed and wrapped in a vesicle, forming a phagosome
whats the third step of phagocytosis?
lysosomes within pagocyte fuse with the phagosome and Hydrolytic enzyme stored inside, break down the pathogen
what happens in the fourth step of phagocytosis?
phagocyte then present the pathogens antigen on its plasma membrane, activates other immune cells.
it becomes an anitgen-presenting cell
