University:
Stanford University
Course:
MED 101 | Human Anatomy
Academic year:

2024
Views:

263

Pages:

1
Author:

larbi43100

‭Properties‬‭:‬ ‭ It is well represented at 1.5 to 7 giga /L. The polynuclear neutrophils are divided into 2‬ ✪ ‭compartments: circulatory and a margination cell which are attached to the endothelial cells and‬ ‭which can be mobilized very quickly with adrenaline during significant physical effort. The‬ ‭intravascular lifespan is 24 hours then they pass into the tissues where they also live for 24 hours‬ ‭then they are eliminated in the secretions.‬ ‭ Below 1.5 giga/L it’s a neutropenia. Below 0.5 giga/L we speak of agranulocytosis which is often‬ ✪ ‭seen in patients with anticancer treatments because these anticancer drugs are not specific to‬ ‭malignant cells but have a general action on cells which have rapid renewal capacities, therefore‬ ‭cells digestive, the cells of the hematopoietic bone marrow. When there is chemotherapy there is a‬ ‭risk of agranulocytosis so these are patients who have the first line of defense which is made up of‬ ‭polynuclear neutrophils which are suppressed and the risk of infection is very increased and if there‬ ‭is infection the risk of mortality is significant.‬ ‭ The polynuclear neutrophil has a significant mobilization capacity of around 20 micrometers per‬ ✪ ‭minute. Movement is generally random unless there is a gradient of chemokine concentration and at‬ ‭that moment we will have a migration which will be oriented. Spontaneously, neutrophils can roll‬ ‭over endothelial cells during marginalization phenomena. If there is a local chemokine gradient‬ ‭with activation of endothelial cells, there will be recruitment, i.e. the polynuclear will remain a little‬ ‭longer in contact with these endothelial cells.‬ ‭ There will be activation of a certain number of molecules which will increase adhesion and then‬ ✪ ‭opening of the endothelial cells to allow the passage of neutrophils, destruction of the basal cell and‬ ‭migration of the polynuclear cells to the tissue level where it exerts its action.‬ ‭ ‬‭Action :‬‭Destruction of microorganisms at the tissue‬‭level, there was chemotaxis = recruitment of‬ ✪ ‭these polynuclear cells. There is adhesion between polynuclear neutrophils and bacteria,adhesion‬ ‭favored by the presence of antibodies, certain molecules of complement :this is the phenomenon of‬ ‭opsonization. When there is significant contact there is membrane activation with emission of‬ ‭pseudopodia which fuse so there is internalization of the bacteria with the constitution of a‬ ‭phagosome then there is migration of the granules from the lysosome towards this phagosome‬ ‭which will give a phagolysosome. In this one there is a significant lowering of the PH which makes‬ ‭it possible to activate lysozyme and the action of lactoferrin which has antibacterial activity.‬ ‭ The most important thing is the presence of myeloperoxidase in this lysosome and this‬ ✪ ‭myeloperoxidase will make it possible to couple halogenated radicals (clore, iodine) to hydroxyl‬ ‭radicals which will be very toxic towards bacteria. The activity of producing oxygen radicals is very‬ ‭important. So the myeloperoxidase allows the production of oxygen radicals, superoxide dismutase‬ ‭allows the transformation of superoxide anions into hydrogen peroxide which is very toxic for the‬ ‭bacteria.‬