Editing Haemodynamic response (section)

====Ischemia====
A decrease in circulation in the brain vasculature due to [[stroke]] or injury can lead to a condition known as [[ischemia]]. In general, decrease in blood flow to the brain can be a result of thrombosis causing a partial or full blockage of blood vessels, [[hypotension]] in systemic circulation (and consequently the brain), or cardiac arrest. This decrease in blood flow in the cerebral vascular system can result in a buildup of metabolic wastes generated by neurons and glial cells and a decrease in oxygen and glucose delivery to them. As a result, cellular energy failure, depolarization of neuronal and glial membranes, [[edema]], and excess [[neurotransmitter]] and calcium ion release can occur.<ref>Arcinlegas, David B., MD. "Hypoxic-Ischemic Brain Injury | Internationalbrain.org."Hypoxic-Ischemic Brain Injury | Internationalbrain.org. International Brain Injury Association, Mar. 2010. Web. <http://www.internationalbrain.org/?q=node/131></ref> This ultimately ends with cell death, as cells succumb to a lack of nutrients to power their metabolism and to a toxic brain environment, full of free radicals and excess ions that damage normal cell organelle function.