Question

Assertion: Muscle contracts upon stimulation normally when it is relieved from muscle fatigue.
Reason: The vein which is taking away blood from the muscle transports accumulated lactic acid from the muscle to the liver.

• A. Both assertion and reason are false.
• B. Both assertion and reason are true and the reason is the correct explanation of the assertion.
• C. Assertion is true but reason is false.
• D. Both assertion and reason are true and the reason is not the correct explanation of the assertion.

Answer 1

The correct option is B Both assertion and reason are true and the reason is the correct explanation of the assertion.

Muscle fatigue is the repeated activation of muscle due to the accumulation of lactic acid which is formed by the anaerobic breakdown of glycogen. Glycogen breaks down to pyruvic acid which inturn gets converted to lactic acid. The buildup of lactic acid causes muscle fatigue.
The lactic acid is transported to the liver where it is converted back to pyruvic acid which is broken down in Krebs cycle to provide ATP or is converted back to glucose which is released into circulation to be absorbed by the skeletal muscle to rebuild the glycogen reserve. Muscle contraction continues.
The shuffling of lactic acid to the liver and glucose back to the skeletal muscle is called the Cori cycle.