(from an Air Force manual)
Hypoxia
Hypoxia is a state of oxygen deficiency in the body which is sufficient to cause an impairment of function. Hypoxia is caused by the reduction in partial pressure of oxygen, inadequate oxygen transport, or the inability of the tissues to use oxygen.
In brief, being drunk is kind of the same as being exposed to high altitude. In both cases, oxygen to your brain and muscles is reduced.
Hypoxic Hypoxia is a reduction in the amount of oxygen passing into the blood. It is caused by a reduction in oxygen pressure in the lungs, by a reduced gas exchange area, exposure to high altitude, or by lung disease. [This is the hypoxia that is a hazard to aviators.]
Hypemic Hypoxia is defined as a reduction in the oxygen carrying capacity of the blood. It is caused by a reduction in the amount of hemoglobin in the blood or a reduced number of red blood cells. A reduction in the oxygen transport capacity of the blood occurs through blood donation, hemorrhage, or anemia. A reduction in the oxygen carrying capacity of the blood occurs through drugs, chemicals, or carbon monoxide. [This hypoxia usually experienced by smokers.]
Stagnant Hypoxia is an oxygen deficiency due to poor circulation of the blood or poor blood flow. Examples of this condition are high "G" forces, prolonged sitting in one position or hanging in a harness, cold temperatures, and positive pressure breathing. [This hypoxia usually experienced when sitting for hours in a boring class.]
Histotoxic Hypoxia is defined as the inability of the tissues to use oxygen. Examples are carbon monoxide and cyanide poisoning. Certain narcotics, chewing tobacco, and alcohol will prevent oxygen use by the tissues. [This hypoxia usually experienced after drinking too much.]