3.5- non specific body defences Flashcards
what is a pathogen?
an organism such as a bacterium or virus that causes disease
2 ways immunity is effective
resist infection by a pathogen
destroy the organism if it succeeds in invading and infecting the body
what are the 3 lines of defences?
first two are non-specific
third is specific
how do non-specific lines of defence work?
work against any type of disease causing agent
how do specific lines of defence work?
components each work against a particular pathogen
2 ways physical barriers are used
closely packed epithelial cells in the skin protect against bacteria and viruses
epithelial cells make up the mucous membranes lining the body’s digestive and respiratory tracts
1 use of a chemical barrier
skin and mucous membranes fight against potential pathogens
4 chemical secretions produced against invading pathogens
tears
saliva
mucus
stomach acid
function of sweat
keeps the skin at a low pH where most organisms cant thrive
function of tears/saliva
tears/saliva contain enzyme lysozyme that digests cell wall of bacteria
function of mucus
traps micro organisms and cilia can remove the mucus
function of stomach acid
destroys many of the microbes that have been swallowed
what is the inflammatory response?
the inflammatory response is a localised defence mechanism that is used when the body suffers physical injury
3 steps of the inflammatory response
following injury, mast cells become activated and release large quantities of histamine
histamine results in blood vessels of injured area undergoing vasodilation and capillaries becoming more permeable
additional supply of blood leads to the injured area becoming red and inflamed, the accumulation of phagocytes and clotting elements at the site of infection
2 things that cause the body to use the inflammatory response
invasion by microorganisms
cut
where are mast cells found?
mast cells are found in connective tissue throughout the body
what do mast cells possess and what do those things contain?
possess many granules
granules contain histamine
what are mast cells closely related to?
white blood cells
4 steps of how phagocytes destroy pathogens during phagocytosis
phagocytes detect chemicals released by pathogens
move towards the pathogen
phagocyte engulfs invader by infolding the cell membrane
this is pinched off to form a vacuole
what does a phagocytes cytoplasm have a rich supply of and what do they contain?
phagocytes cytoplasm has a rich supply of lysosomes
contain digestive enzymes
function of some lysosomes
some lysosomes fuse with vacuole and release their enzymes into it digesting the bacterium
breakdown products are absorbed by the phagocyte
what does the phagocyte release after digestion of the microorganism and what do they do?
after digestion of microorganisms, phagocyte releases cytokines
these attract more phagocytes to the site of infection
what may build up at the infected site and as what?
dead bacteria and phagocytes may build up at infected site
pus
what are cytokines and what do they come from?
cytokines are cell signalling protein molecules
secreted by white blood cells that arrived at the site of injury or infection
function of cytokines
function of cytokines is to act as a signal to other specific white blood cells making them accumulate at site of infection