Muscle anaerobic glycolysis

Muscle anaerobic glycolysis yields lactate - Sir Frederick Gowland Hopkins (UK, shared Nobel Prize, Medicine, 1929, growth stimulating vitamins) Sir Archibald Hill (UK) ... 

Glucose derived from muscle glycogen and metabolized by anaerobic glycolysis is the major fuel source. Blood glucose and free fatty acids are the major fuel sources. 

Skeletal muscle functions under both aerobic (resting) and anaerobic (eg, sprinting) conditions, so both aerobic and anaerobic glycolysis operate, depending on conditions. 

Gluconeogenesis Formation of glucose from precursors other than carbohydrates (especially by the liver and kidney) using amino acids from proteins, glycerol from fats, or lactate produced by muscle during anaerobic glycolysis. 

Fast-twitch muscle fibers have a high capacity for anaerobic glycolysis but are quick to fatigue. They are involved primarily in short-term, high-intensity exercise. Slow-twitch muscle fibers in arm and leg muscles are well vascularized and primarily oxidative. They are used during prolonged, low-to-moderate intensity exercise and resist fatigue. Slow-twitch fibers and the number of their mitochondria increase dramatically in trained endurance athletes. 

Short bursts of high-intensity exercise are supported by anaerobic glycolysis drawing on stored muscle glycogen. 

Hypoxia deprives the ETC of sufficient oxygen, decreasing the rate of ETC and ATP production. When ATP levels fell, glycolysis increases and, in the absence of oxygen, wiU produce lactate j (lactic acidosis). Anaerobic glycolysis is not able to meet the demand of most tissues for ATP, I especially in highly aerobic tissues like nerves and cardiac muscle. 

Zebrafish larvae possess two types of skeletal muscle fibers. Slow (red) muscle fibers, a superficial monolayer on the siuface of the myotome, are equipped for oxidative phosphorylation, can generate relatively large stores of energy, and are most resistant to fatigue. Fast (white) muscle fibers, in the deep portion of the myotome, are least resistant to fatigue because they rely on anaerobic glycolysis for... 

During anaerobic glycolysis in the muscles and erythrocytes, glucose is converted into lactate, releasing protons in the process (see p. 338). The synthesis of the ketone bodies acetoacetic acid and 3-hydroxybutyric acid in the liver (see p. 312) also releases protons. Normally, the amounts formed are small and of little influence on the proton balance. If acids are formed in large amounts, however (e. g., during starvation or in diabetes mellitus see p. 160), they strain the buffer systems and can lead to a reduction in pH (metabolic acidoses lactacidosis or ketoacidosis). 

In muscle tissue under hypoxic conditions, the energy needs of the tissue may be partially supplied by anaerobic glycolysis. 

Muscle activity involves processes such as aerobic and anaerobic glycolysis and is therefore accompanied by an increased pyruvate production. Consequently, the pyruvate transamination product alanine will be increased after exercise. Heavy exercise may be associated with an increased need of creatine biosynthesis from arginine. Ornithine is a by-product of this pathway and may be increased under these conditions. 

Efficiency of ATP Production in Muscle The transformation of glucose to lactate in myocytes releases only about 7% of the free energy released when glucose is completely oxidized to C02 and H20. Does this mean that anaerobic glycolysis in muscle is a wasteful use of glucose Explain. 

Tissues using anaerobic glycolysis In anaerobic glycolysis, NADH is reoxidized to NAD by the conversion of pyruvate to lactic acid. This occurs in cells such as erythrocytes that have few or no mitochondria, and in tissues such as exercising muscle, where production of NADH exceeds the oxidative capacity of the respiratory chain. 

Type II muscle fibers (white muscle, fast muscle) (Table 6) contribute to rapid muscle contraction by using energy obtained from stored ATP, and ATP production from creatine phosphate and anaerobic glycolysis of glycogen. However, the myoglobin content of these fibers is low [144,145], which may lead to less marked increases in serum myoglobin and creatine phosphokinase (CPK) in patients with ALPE. 

The properties of anaerobic metabolism are also strongly determined by the isozyme arrays present at each step in the anaerobic glycolysis of vertebrate muscle, so the question arises as to whether or not training can lead to adjustments... 

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