Tag: features of a muscle

Skeletal muscles show muscle fibres having well developed sarcoplasmic reticulum these muscles are easily fatigued during exercise. Skeletal muscles show voluntary movements.  These can be found in close association with limb bones.

The internal movements are performed by the involuntary muscles. The involuntary muscles function on their own and cannot be controlled willingly. The cardiac muscles are the involuntary muscles which are responsible for the pumping of the heart. The heart pumps and supplies the oxygenated blood to the different tissues in the body. The smooth muscles are responsible for carrying out peristalsis in the tube like structures of the alimentary canal.

The correct option is D.

• Generally, the glucose undergoes metabolism in the presence of oxygen to form ATP(adenosine triphosphate) which is essential for the muscle contraction but during vigorous 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.
  
• Feeling of fatigue after running fast for some time is due to the accumulation of lactic acid in muscles.
  
• So, the correct answer is 'Accumulation of lactic acid in muscles'.

The body prefers to generate most of its energy using aerobic methods. During physical exercise such as lifting heavy weights, energy production is faster than our bodies can adequately deliver oxygen. In those cases, the working muscles generate energy anaerobically. This energy comes from glucose through a process called glycolysis, in which glucose is broken down or metabolized into a substance called pyruvate. When the body has plenty of oxygen, pyruvate is shuttled to aerobic pathway to be further broken down for more energy. But when oxygen is limited, the body temporarily converts pyruvate into a substance called lactate and accumulates in the muscle. 

• 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.