Fissure filling is a treatment that improves the apparent clarity of a gemstone by removing air and replacing it with a substance that has a refractive index similar to the host material. Many different substances may be used to fill fissures: oils, resins, waxes, glass, and various polymers, to name a few.
Cerebral autoregulation is a process in mammals, which aims to maintain adequate and stable cerebral blood flow.hile most systems of the body show some degree of autoregulation, the brain is very sensitive to over-and underperfusion. Cerebral autoregulation plays an important role in maintaining an appropriate blood flow to that region.
The control of cerebral blood flow is complex, and only beginning to be elucidated. Studies have identified three key regulatory paradigms. The first is cerebral pressure autoregulation, which maintains a constant flow in the face of changing cerebral perfusion pressure.Flow-metabolism coupling refers to the brains ability to vary blood flow to match metabolic activity.entral to these three paradigms are two cell types: endothelium and astrocytes. The endothelium produces several vasoactive factors that are germane to the regulation of cerebral blood flow: nitric oxide, endothelium-dependent hyperpolarization factor, the eicosanoids, and the endothelins.