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How does muscle cells meets its energy requirement?
Muscle cells use fatty acids, glucose, and amino acids as energy sources. Most cells use glucose for ATP synthesis, but there are other fuel molecules equally important for maintaining the body’s equilibrium or homeostasis. Between meals, cardiac muscle cells meet 90% of their ATP demands by oxidizing fatty acids.
How do muscle cells take up glucose?
Glucose enters the muscle cell via facilitated diffusion through the GLUT4 glucose transporter which translocates from intracellular storage depots to the plasma membrane and T-tubules upon muscle contraction.
How do muscles use glycogen?
During intense, intermittent exercise and throughout prolonged physical activity, muscle glycogen particles are broken down, freeing glucose molecules that muscle cells then oxidize through anaerobic and aerobic processes to produce the adenosine triphosphate (ATP) molecules required for muscle contraction.
Do muscle cells need glucose?
The glycogen in muscle cells can be converted back into glucose and used by those cells to make ATP. This reduces the need to draw glucose from the blood but muscle cells cannot release glucose into the blood for other cells to use. Muscle cells can release pyruvate and lactate (from glycolysis) into the blood.
How do muscle cells convert glucose into ATP?
Glycolysis converts glucose to pyruvate, water and NADH, producing two molecules of ATP. Excess pyruvate is converted to lactic acid which causes muscle fatigue. Cellular respiration produces further molecules of ATP from pyruvate in the mitochondria.
Where do muscles get glycogen?
The synthesis of muscle glycogen depends upon uptake of glucose molecules from the blood into muscle cells. When carbohydrates are ingested at rest—and in the recovery period after exercise—the entry of glucose into muscle cells is facilitated by the hormone insulin.
How is glycogen synthesized in the body?
The synthesis of muscle glycogen depends upon uptake of glucose molecules from the blood into muscle cells. When carbohydrates are ingested at rest—and in the recovery period after exercise—the entry of glucose into muscle cells is facilitated by the hormone insulin.
How is glucose converted to glycogen in muscle cells?
When glucose enters the muscle cell at rest or during exercise, it is immediately phosphorylated to glucose-6-phosphate by the enzyme hexokinase. Glucose-6-phosphate can then be oxidized through glycolysis and the Krebs cycle to produce ATP for immediate use by the cell, or it can be stored as glycogen.
What is glycogen and why is it important for athletes?
For the body to be prepared for subsequent training and competition, it is essential that glycogen stores in muscle and liver be replenished as rapidly as possible.
What happens to glycogen stores during physical activity?
Glycogen stores in liver and muscle decrease during physical activity; the longer and more intense the activity, the greater the rate and overall reduction of glycogen stores.