Blood sugar regulation cells in the pancreatic islets are among the most well understood and important. If the blood glucose level falls to dangerous levels (as during very heavy exercise or lack of food for extended periods), the alpha cells of the pancreas release glucagon, a hormone whose effects on liver cells act to increase blood glucose levels. They convert glycogen into glucose (this process is called glycogenolysis). The glucose is released into the bloodstream, increasing blood sugar. Hypoglycemia, the state of having low blood sugar, is treated by restoring the blood glucose level to normal by the ingestion or administration of dextrose
Blood-oxygen-level dependent imaging correlated fluctuations called resting state fMRI. Its proof of concept of blood-oxygen-level dependent contrast imaging was provided by Seiji Ogawa and Colleagues in 1990, following an experiment which demonstrated that an "in vivo" change of blood oxygenation could be detected with MRI.In Ogawa's experiments,blood-oxygen-level dependent imaging of rodent brain slice contrast in different components of the air. At high magnetic fields, water proton magnetic resonance images of brains of live mice and rats under anesthetization have been measured by a gradient echo pulse sequence. Experiments shown that when the content of oxygen in the breathing gas changed gradually, the contrast