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 Brain Injury Foundation. The Brain Injury Foundation is dedicated to the prevention of brain damage caused by lack of oxygen and bloodflow to the brain. This injury is known as Hypoxic (low oxygen) Ischemic (low bloodflow) Injury, or HII. Without oxygen reaching the brain, irreversible brain damage starts to occur within 5 minutes. The Mission of our Foundation is to save lives and prevent permanent brain damage of Sudden Cardiac Arrest victims.