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.
The human body needs oxygen to sustain itself. The decrease of oxygen to at least one body part is known as hypoxia. The total lack of oxygen is known as anoxia. Brain cells are destroyed after 4 to 6 minutes without oxygen. When the flow of oxygen to the brain is completely cut off, a person will lose consciousness within 10 seconds. Extended hypoxia leads to brain damage and ultimately death.