The makeup of both water and isopropanol is different from each other due to their polar nature. Water is a polar substance means that it makes poles i.e. positive or negative while on the other hand, isopropanol is non-polar substance so due to this reason water and isopropanol make different layers. If both are polar or nonpolar substances so they will able to mix with each other.
because the blood in the heart gets what's left of oxygenated blood first. first come first serve concept. the heart cells survive longer because they have oxygenated blood longer and more frequently. if the person is not breathing the oxygen in the blood might run out by transferring to cardiovascular cells before it gets to the brain.