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.
Stroke: Time = Brain Damage. Every second counts when seeking treatment for a stroke. When deprived of oxygen, brain cells begin dying within minutes. There are clot-busting drugs that can curb brain damage, but they need to be used within three hours -- up to 4.5 hours in some people -- of the initial stroke symptoms.Once brain tissue has died, the body parts controlled by that area won't work properly. This is why stroke is a top cause of long-term disability.here are clot-busting drugs that can curb brain damage, but they need to be used within three hours -- up to 4.5 hours in some people -- of the initial stroke symptoms. Once brain tissue has died, the body parts controlled by that area won't work properly.