Second line of defence Flashcards
when does the second line of defenece operate
when a pathogen has crossed the first line of defence
what cells does the second line of defence involve
leukocytes - neutrophils, eosinophils, mast cells, macrophages, dendritic cells, natural killer cells
what are the cells that are phagocytes
dendritic cells, macrophages and neutrophils
what do macrophages do
consume and destroy forgein or dead material by engulfing it via endocytosis, have lysosomes contains lysozymes which destroy the forgein/dead material
aside from functioning as phagocytes, macrophages and dendritic cells are also
antigen presenting cells, they contain MHC II markers, on which they present antigens from the consumed material
where are neutrophils found and how do they compare to other phagocytes
most common type of WBC, found in the blood stream and pus
where are monocytes found and how do they compare to other phagocytes
travels through the blood where it eventually migrates into the tissues of the body, here it specialises into macrophage, largest WBC
where are macrophages found and how do they compare to other phagocytes
found everywhere inside the body, aside from function as a phagocyte and antigen presenting cell, they also produce a wide range of chemicals, enzymes, complememnt proteins and regulatory factors
where are dendritic cells found and how do they compare to other phagocytes
found on the surface of body (skin, eyes, mucous membranes), similar to macrophages
function of natural killer cells
upon finding a self cell displaying non-self antigens on its surface, NK cells release a death lignand - a siggnally molecule that stimulates the cell to die by apoptosis
when is a natural killer cell activated
recruited to the sight of infection when infected cells release a cytokine callde interferon, kills cancerous cells or cells infected by a virus
structure of natural killer cell
large granulated cells conatining the killer inhibitory receptor and killer activation receptor
killer inhibitory receptor
examines the surface for MHCI markers, prevents NK cell from killing healthy cell
killer activation reeceptor
binds to certain molecules which appear on ce;;s underhoing cellular stress
where do mast cells reside
in connective tissue, such as under the skin and the connective tissue surrounding blood vessels
