During anaerobic exercise, the Cori cycle connects which two metabolic pathways?

Question

Quizplus · Accepted Answer

11ecba2d_0e9a_c033_a3bf_f932f3c7a5ee_MD0008_00 During glycolysis, NAD⁺ is converted to NADH by the enzyme glyceraldehyde-3-phosphate (GAP) dehydrogenase. For glycolysis to continue, NAD⁺ must be regenerated. Under aerobic conditions, electrons from NADH can be transferred to the electron transport chain (ETC) and ultimately to oxygen. However, in anaerobic conditions, NAD⁺ cannot be regenerated by the ETC because there is insufficient oxygen to accept electrons. Consequently, NADH donates electrons to pyruvate, which is reduced to lactate in the process. Lactate that builds up from this mechanism must be removed from the system because it can lead to muscle pain and nausea. The lactate in muscles enters the bloodstream, which carries it to the liver. In the liver, lactate is converted to glucose during gluconeogenesis and is carried back to muscles by the blood. The process of carrying lactate from the muscle to the liver and moving regenerated glucose from the liver back to muscles is called the Cori cycle, which connects gluconeogenesis and glycolysis. (Choice A) Glycogenolysis is the consumption of glycogen to form glucose-6-phosphate, and the citric acid cycle is the consumption of acetyl-CoA (formed from pyruvate) to generate CO₂, GTP, NADH, and FADH₂. Neither pathway is part of the Cori cycle. (Choice B) The urea cycle processes nitrogen from amino acids for excretion, and gluconeogenesis generates glucose from pyruvate and other precursors. Both pathways occur primarily in the liver, and they are not connected by the Cori cycle. (Choice C) The pentose phosphate pathway produces ribose 5-phosphate and NADPH using glucose as a starting material. Glycogenesis is the production of glycogen from glucose. The two pathways diverge from each other and are not connected by the Cori cycle. Educational objective: During anaerobic exercise, pyruvate is reduced to lactate to regenerate NAD⁺. Lactate that builds up in muscles is sent to the liver, where it is converted back to glucose and returned to muscles. This process is called the Cori cycle.

During Anaerobic Exercise, the Cori Cycle Connects Which Two Metabolic