Muscle cells when an individual is excerising heavily and the muscle becomes oxygen deprived convert pyruvate to lactate What happens in skeletal cells?
During heavy exercise, when skeletal muscle cells are oxygen-deprived, they convert pyruvate to lactate through a process called anaerobic glycolysis. Here's what happens in skeletal cells during this process:
1. Glycogen Breakdown: When oxygen is limited, skeletal muscle cells break down stored glycogen to generate glucose. This glucose is then available for energy production.
2. Glycolysis: Glucose undergoes a series of enzymatic reactions known as glycolysis, which occurs in the cytoplasm of the muscle cells. Glycolysis breaks down glucose into two molecules of pyruvate.
3. Pyruvate to Lactate Conversion: Under anaerobic conditions, when oxygen is scarce, the pyruvate produced during glycolysis cannot enter the mitochondria for further energy production via the citric acid cycle (Krebs cycle). Instead, it is converted into lactate.
- -
Pyruvate Dehydrogenase Inhibition: When there is inadequate oxygen, reduced nicotinamide adenine dinucleotide (NAD+) levels in the cytoplasm increase. These reduced NAD+ act as negative feedback inhibitors of pyruvate dehydrogenase, the enzyme that converts pyruvate into acetyl-CoA for entry into the citric acid cycle.
High NADH levels lead to a decrease in pyruvate dehydrogenase activity, causing pyruvate to be diverted to lactate production.
4. Lactate Accumulation: As pyruvate is rapidly converted into lactate, it begins to accumulate in the skeletal muscle cells. The accumulation of lactate is associated with muscle fatigue and the burning sensation that can be felt during intense exercise.
5. Lactate Transport: Once lactate reaches a certain concentration within the muscle cells, it needs to be transported out into the bloodstream. This is facilitated by specific lactate transporters present in the cell membranes.
6. Lactate Metabolism in Other Tissues: The lactate produced by skeletal muscle cells can be transported to other tissues, such as the liver and heart, where it can be converted back into pyruvate and further metabolized for energy production when oxygen becomes available again.
In summary, during heavy exercise when skeletal muscle cells are oxygen-deprived, they switch to anaerobic glycolysis and convert pyruvate into lactate as a way to continue generating energy and maintain cellular function.