Non-specific animal defences against pathogens - destroying it Flashcards
How is a fever triggered?
cytokines stimulate the hypothalamus to reset and causes the temperature to go up
the hypothalamus is responsible for maintaining body temperature
Why is a fever useful?
high temperatures inhibit pathogen reproduction
the immune systems works faster at higher temperatures
What are phagocytes? What are the two types?
phagocytes are specialised WBC that engulf and destroy pathogens
the two main types are neutrophils and macrophages
they build up at the site of an infection
pus consists of dead neutrophils and pathogens
How do phagocytes recognise a pathogen?
pathogens produce chemicals that attract phagocytes
they recognise non-self proteins on the pathogen - not specifically a pathogen, but a cell or organisms that is non-self
How does the phagocyte destroy the pathogen?
it engulfs the pathogen and encloses it in a vacuole called a phagosome
the phagosome combines with a lysosome to form a phagolysosome
enzymes from the lysosome digest and destroy the pathogen
What is the difference between phagocytosis in macrophages and neutrophils?
macrophages undergo a more complex process
when it has digested the pathogen, it combines antigens from the pathogen surface membrane with special glycoproteins in the cytoplasm called the major histrocompatibility complex (MHC)
the MHC moves these pathogen antigens to the macrophage’s own surface membrane, becoming an antigen-presenting cell (APC)
these antigens now stimulate other cells involved in the specific immune sysstem response
What does the number of different types of lymphocytes in a blood smear?
indicates whether it is a specific response or not
What are cytokines? How are they produced?
phagocytes that have engulfed a pathogen produce them
they act as cell-signalling molecules, informing other pathogens to move to the site of infection
also they increase the body temperature and stimulate the specific immune system
What are opsonins?
chemicals that bind to pathogens and tag them so they can be more easily recognised by pathogens
phagocytes have receptors on their cell membreanes that bind to common opsonins and the phagocyte then engulfs the pathogen
e.g. immunoglobuling G and M have the strongest effect
