MUSCLE PHYSIOLOGY

Detailed explanation-1: -If NADH cannot be oxidized through aerobic respiration, another electron acceptor is used. Most organisms will use some form of fermentation to accomplish the regeneration of NAD+, ensuring the continuation of glycolysis.

Detailed explanation-2: -In the process of fermentation the NADH + H+ from glycolysis will be recycled back to NAD+ so that glycolysis can continue. In the process of glycolysis, NAD+ is reduced to form NADH + H+. If NAD+ is not present, glycolysis will not be able to continue.

Detailed explanation-3: -Cells have only a limited amount of NAD+. When it is reduced to NADH by catabolic reactions, it must be oxidized back to NAD+ so that those reactions can continue. If the organism is carrying out aerobic respiration, the electrons from NADH can enter the electron transport system, reforming NAD+.

Detailed explanation-4: -During the absence of oxygen (anaerobic conditions) and in the cells lacking mitochondria, anaerobic glycolysis prevails. The pyruvate is reduced to lactate as NADH is reoxidized to NAD+ by lactate dehydrogenase. This process is an important source of ATP for cells that lack mitochondria such as erythrocytes.

Detailed explanation-5: -Lactic acid fermentation converts pyruvate (a slightly oxidized carbon compound) to lactic acid. In the process, NADH is oxidized to form NAD+.