5.5 The components of innate immunity

what are pathogen-associated molecular patterns?

molecules that are found in pathogens but are not found in. host, allowing them to be recognised foreign

what are phagocytes?

specialised white blood cells that engulf and destroy foreign particles

what is a phagosome?

a membrane bound vesicle within the phagocyte

what is phagocytosis?

bulk movement of the foreign particles into cells where the phagocyte engulfs a particle to form a phagosome

what are the components involved in the second line of defence?

• immune cells

• soluble proteins

• inflammation

what are the steps involved in phagocytosis?

1. The pathogen is identified by a pattern recognition receptor (PRR) and engulfed by the plasma membrane

2. The pathogen is engulfed by the phagosome

3. Lysosomes fuse with the phagosome (forming a phagolysosome).

4. Toxic chemicals from the lysosome (include free radicals, lysozymes and proteases) digest and destroy the pathogen.

5. Indigestible material is discharged from the phagocytic cell by a process of exocytosis.

what’s the pattern recognition receptor (PRR)?

protein receptors present on phagocytic cells of the innate immune system that enable these cells to recognise and bind to pathogens with recognition being at.a generic

what are the types of leukocytes (white blood cells)?

• phagocytes

• macrophages

• neutrophils

• dendritic cells

• mast cells

• natural killer cells

• eosinophils

what are macrophages?

these cells inject pathogens

once the pathogen has been consumed, they are destroyed within the macrophage.

they are also antigen- presenting, meaning that when they consume foreign material, they present their materials on they surface as MHC II markers.

what are neutrophils?

also complete phagocytosis,

the most common leukocyte,

speedy and release antimicrobial compounds to break down bacteria/fungi. They die after eating the pathogen

what are dendritic cells?

undergo phagocytosis and act as a antigen presenting cell

what are mast cells?

detect damage to surrounding cells of connective tissue, release histamine from granules, initiates an inflammatory response and attracts phagocytes

what are natural killer cells?

upon finding a cell missing sufficient self MHC I markers, relate a death ligand (to pierce the cells all of antigens during phagocytosis) which stimulates the cell to conduct apoptosis and die,

also releases cytokines to signal immune response at a specific location

what are eosinophils?

white blood cells that secrete cytotoxic chemicals in parasitic infections

what cells in the immune system are found in blood?

• neutrophils

• eosinophils

• natural killers (NK)

what cells in the immune system are found in tissues?

• macrophages

• dendritic cells

• mast cells

what are interferons?

signalling molecules and are cytokines which aids in communication between immune cells that are released from virus infected host cells to signal to other cells that there is a virus in the environment

what do interferons help with?

• it help to reduce the susceptibility to these cells to the virus and causes the cells to up regulate production of MHC I markers

• cytokines produces by virally infected self cels to block translation, preventing further infection of other self-cells

what are complement proteins?

helper cells that increase antibody affinity(attraction) to attack pathogens

enabled by a signal cascade into the cell

what happened when complement proteins are activated?

• they act as chemo attractants, attracting phagocytes

• they stick on the outside of pathogens and make it easier for the phagocytes to recognise them as foreign -

• they form a cell-destroying membrane attack complex