Hg) Po2 IN AIR (mmHg) Po2 IN ALVEOLI (mmHg) ARTERIAL OXYGEN SATURATION (%) 0 760 159* 104 97 10,000 523 110 67 90 20,000 349 73 40 70 30,000 226 47 21 20 40,000 141 29 8 5 50,000 87 18 1 1 *this value differs from table 1 because the author used the value for the concentration of O2 as 21%. The author of table 1 choose to use the value as 20%. CELLULAR RESPIRATION In a normal, non-stressed state, the respiratory system transports oxygen from the lungs to the cells of the body where it is used in the process of cellular respiration. Under normal conditions this transport of oxygen is sufficient for the needs of cellular respiration. Cellular respiration converts the energy in chemical bonds into energy that can be used to power body processes. Glucose is the molecule most often used to fuel this process although the body is capable of using other organic molecules for energy. The transfer of oxygen to the body tissues is often called internal respiration (Grollman, 1978). The process of cellular respiration is a complex series of chemical steps that ultimately allow for the breakdown of glucose into usable energy in the form of ATP (adenosine triphosphate). The three main steps in the process are: 1) glycolysis, 2) Krebs cycle, and 3) electron transport system. Oxygen is required for these processes to function at an efficient level. Without the presence of oxygen the pathway for energy production must proceed anaerobically. Anaerobic respiration sometimes called lactic acid fermentation produces significantly less ATP (2 instead of 36/38) and due to this great inefficiency will quickly exhaust the available supply of glucose. Thus the anaerobic pathway is not a permanent solution for the provision of energy to the body in the absence of sufficient oxygen. The supply of oxygen to the tissues is dependent on: 1) the efficiency with which blood is oxygenated in the lungs, 2) the efficiency of the blood in deliv...
