Po2 = partial pressure of oxygen; measures how well your lungs bring oxygen into your bloodstream. Oxyhemoglobin dissociation curve = a mathematical relationship, that is viewed as a graph, showing the amount of oxygen that combines with hemoglobin as a function of the partial pressure of oxygen. Acclimatized = adaptation to a new climate (such as temperature, altitude, etc) Hypoxia = deficiency in the amount of oxygen reaching the tissues. 2,3 dpg = present in rbc; binds with greater affinity to deoxygenated hemoglobin than it does to oxygenated hemoglobin. Medium = 5000 - 10,000 feet = we are concerned with this altitude in relation to athletics. High = >10,000 feet = over 40 million people live/work between 10,000-18,000 feet (3048m 5486m) Barometric (air) pressure decreases when altitude increases. (i. e. , as the weight of the column of air above the point of measurement decreases). The chemical composition is the same up to 20,000m.