Brain Is Highly Metabolic And Important Organ Of The Body

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Brain is highly metabolic and important organ of the body. Even though it weighs only 2% body weight, however, requires disproportionate amount (~20 %) of the total blood flow. Unprecedented fall in cerebral blood flow (CBF) would quickly lead to unconsciousness and, if sustained for longer period of time would result in brain damage and death. Therefore, CBF is tightly regulated in the brain, as it facilitates the delivery of essential substrates required for metabolism and removal of metabolic by products.
1.1.1 Mechanism regulating CBF
The cerbrovasculature is always under the combined influence of a number of physical and chemical stimuli that adjust vascular caliber/resistance so as to alter the blood supply to different parts of the brain (Bayliss, 1902; Lassen, 1959). Autoregulation and metabolic coupling are 2 important mechanism which regulates the CBF to the brain. Autoregulation ensures that constant blood flow is supplied in the face of changes in perfusion pressure. The mechanism through which autoregulation controls the blood flow during pressure changes is thought to be myogenic in nature but other factors such as metabolic (CO2, O2, and so on) factors also assert some influence (Osol et al., 2002; Paulson et al., 1990; Peterson et al., 2011). Furthermore, metabolic coupling mechanisms ensure that blood flow is increased in active regions. CBF is highly variable across the brain and largely dependent on neuronal activity, thus, an increase in neuronal
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