Tag: zoology

• When you exercise, your muscles move more vigorously than when you are at rest. Their metabolic rate increases. 
• They need more energy, so they produce more of the chemical energy molecule ATP. 
• Your muscles begin converting glucose into lactic acid instead of energy when anaerobic exercise takes over, power output drops and fatigue sets in. Hence, when Muscles run out of oxygen muscles begin converting glucose into lactic acid.

Generally, the glucose undergoes metabolism in the presence of oxygen to form ATP(adenosine triphosphate) which is essential for the muscle contraction but during strenuous exercise, the body cannot meet the oxygen demand and the glucose undergoes metabolism in the absence of oxygen which results in the formation and accumulation of lactic acid.Hence during strenuous exercise,glucose is converted into lactic acid.

• During a vigorous physical exercise, lactic acid and carbon dioxide are formed in the muscles of the body.
• The production of lactic acid can be prevented by the flow of required oxygen to the muscles thus, our body uses more oxygen than replenished.
  
• Therefore, after a vigorous exercise people pant due to to decrease in the oxygen level in the body.
• So, the correct answer is 'Oxygen debt'.

All or none law is the principle that states that the strength by which a muscle fiber responds to a stimulus is independent of the strength of the stimulus. If that stimulus exceeds the threshold potential, the muscle fiber will give a complete response, otherwise, there is no response. 

• Lactic acid is formed and accumulated in the muscle under conditions of high energy demand, rapid fluctuations of the energy requirement and insufficient supply of O2.
•  During exercise, there is a progressive reduction in the ability to produce muscle forces processes within the nervous system, as well as within the muscles contribute to this fatigue. 
•  Finally, the small-diameter muscle afferents that increase firing with exercise and fatigue. Hence, Lactic acid causes fatigue in muscles due to the Sensitivity of neuromuscular junction.

• Myofibril activity is required for muscle contraction on the molecular level. 
• When ATP binds to myosin, it separates from the actin of the myofibril, which causes a contraction.
  
• The muscle contraction cycle is triggered by calcium ions binding to the protein complex troponin, exposing the active-binding sites on the actin.
  
• ATP then binds to myosin, moving the myosin to its high-energy state, releasing the myosin head from the actin active site.
• When ATP is exhausted resulting in fatigue, lactic acid is produced 

Muscle fatigue is the reduction in force of contraction of a muscle after prolonged stimulation. In the absence of oxygen, skeletal muscle of human beings can contract for a short time, but it gets fatigued soon. This is due to the fact that in the absence of oxygen, products of glycolysis mainly lactic acid is not disposed of and accumulates in the muscles. This leads to muscle fatigue and pain in the muscles. A muscle gets fatigued sooner after a strenuous exercise than after a mild exercise. Faster breathing for sometime after a strenuous exercise supplies extra oxygen disposes off excess lactic acid and muscle fatigue disappears.