Introductory Chapter: Primary Concept of Hypoxia and Anoxia

Hypoxia is a pathological condition classified as generalized hypoxia and tissue hypoxia. It is well known that arterial oxygen saturation is a part of the normal physiology. A disparity between oxygen supply and its demand at the cellular level may result in a hypoxic condition. Hypoxia in which there is complete deprivation of oxygen supply is referred to as anoxia. Hypoxia belongs to the most grave factors that can directly impair the function of metabolic pathways in the animal cell. These studies dealt mostly with changes in the structure of pulmonary vessels. Normally, PO2 values of −100 Torr in the alveoli of the lungs to less than 10 Torr in tissues such as the medulla of the kidney and the retina in healthy humans are considered as the range of physiological oxygen levels within the tissues of the body [1]. Hypoxia, which occurs when oxygen levels in the microenvironment of a cell, tissue, or organism are reduced relative to the normal physiological state, is associated with a range of physiological and pathophysiological processes [2].