In those cases, the spread between the bid & ask goes to the market maker as compensation for making a market in a stock. For a liquid stock that is easy for the market maker to turn around and buy/sell to somebody else, the spread is small (narrow).
In cerebral hypoxia, sometimes only the oxygen supply is interrupted. Brain cells are extremely sensitive to a lack of oxygen. Some brain cells start dying less than 5 minutes after their oxygen supply disappears. As a result, brain hypoxia can rapidly cause severe brain damage or death.
In fact, the brain is only able to function for five to six minutes without oxygen before cell death begins to occur. Cell death results from cellular swelling and injury due to excitotoxicity (2). Such damage is sometimes called an Anoxic Brain Injury (ABI) (3). Hypoxia can result from both chronic and acute conditions; however, acute oxygen deprivation is more likely to result in more serious damage and more permanent consequences than in a chronic condition (2).