The biochemical and physiological importance of anaerobic glycolysis

When a human muscle, which comprises exclusively anaerobic (i.e. type II6) fibres is physically active, glycogen conversion to lactate generates all the ATP that is required to support the activity. Type I or Ila fibres use this process only when the demand for ATP exceeds that which can be generated from aerobic metabolism, e.g. during hypoxia. The significance of fhese processes for generation of ATP by muscle during various athletic events is discussed in Chapter 13. 

One condition in which all tissues or organs may use glycogen is the mammalian foetus during birth. This is especially the case if the placenta separates from the uterus prior to birth, which may occur if parturition is slow. In this situation, prior to birth and the first breath, the tissues of the foetus must generate ATP from conversion of glycogen to lactic acid. Survival depends on this process To this end, the glycogen level in the tissues of the foetus increases just prior to birth. 

Cells that use glucose conversion to lactic acid to generate ATP 

Those that depend upon this process are cells in the tissues of the eye, the kidney medulla, the epithelial cells in the 

Kidney medulla From the metabolic point of view the kidney is virtually two organs, the cortex and the medulla. The cortex contains the glomeruli, through which the blood is filtered, the proximal tubules and part of the distal tubules, from which ions and molecules are reabsorbed. The cortex is well supplied with blood so that ATP is generated by the oxidation of fuels. The medulla is metabolically quite different. Here the ATP is required for the reabsorption of ions from the loop of Henle. Some ATP is generated by anaerobic glycolysis, since the supply of blood, and therefore of oxygen, to the medulla is much poorer than to the cortex. This reflects control of the uptake of water and Na+ ions into the blood by the counter current mechanism. This depends on a slow flow of the blood in the capillaries. 

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