Changes

Neutrophils are the first inflammatory cells to enter damaged tissue from the blood after tissue damage has being caused. They are the predominant cell 4 - 6 hours after the beginning of an inflammatory reaction; at 12 hours there are also substantial numbers of [[Macrophages|macrophages]] and at 24 hours there are equal numbers of neutrophils and macrophages.  

Neutrophils are the first inflammatory cells to enter damaged tissue from the blood after tissue damage has being caused. They are the predominant cell 4 - 6 hours after the beginning of an inflammatory reaction; at 12 hours there are also substantial numbers of [[Macrophages|macrophages]] and at 24 hours there are equal numbers of neutrophils and macrophages.  

===Phagocytosis===

===Phagocytosis===

<p>The main role of the neutrophil is to engulf and destroy foreign material. They uptake this material via endocytosis and this surrounds the material in the neutrophil membrane forming a '''phagosome'''. Lysosomes inside the neutrophil then fuse with the phagosome and release their contents degrading the foreign material. Phagocytosing material shortens the lifespan of the neutrophil due to the build up of toxins both from the degraded bacteria etc. and also from its own lysosomes contents.  Most neutrophils die after phagocytosing 5-25 bacteria and the dead neutrophils form [[Necrosis - Pathology#Pus Formation|pus]].</p>

<p>The main role of the neutrophil is to engulf and destroy foreign material. They uptake this material via endocytosis and this surrounds the material in the neutrophil membrane forming a '''phagosome'''. Lysosomes inside the neutrophil then fuse with the phagosome and release their contents degrading the foreign material. Phagocytosing material shortens the lifespan of the neutrophil due to the build up of toxins both from the degraded bacteria etc. and also from its own lysosomes contents.  Most neutrophils die after phagocytosing 5-25 bacteria; sufficient numbers of dead neutrophils form [[Necrosis - Pathology#Pus Formation|pus]].</p>

<p>Neutrophils do not always destroy engulfed particles and may transport engulfed particles to local lymph nodes to be dealt with by other host defence mechanisms. This means that acute inflammation in tissue is can be accompanied by similar acute inflammation in the lymph nodes.</p>

<p>Neutrophils do not always destroy engulfed particles and may instead transport them to local lymph nodes to be dealt with by other host defence mechanisms. This means that acute inflammation in tissue can be accompanied by an acute inflammation in the lymph nodes.</p>

====Recognition====

====Recognition====

<p>To function correctly neutrophils need to correctly identify material that is either foreign (non-self) or requires removal, such as damaged cells. They are able to recognise some foreign material directly but in other circumstances proteins (opsonins) that bind to bacteria and increase binding of the foreign material to the neutrophil.</p>

<p>To function correctly neutrophils need to correctly identify material that is either foreign (non-self) or requires removal, such as damaged cells. They are able to recognise some foreign material directly but in other circumstances proteins (opsonins) that bind to bacteria and increase binding of the foreign material to the neutrophil.</p>