When an individual exercises vigorously for more than 15 minutes, the muscle cells are unable to obtain oxygen from the blood quickly enough. As a result, the muscle cells
a
start anaerobic respiration, producing lactic acid buildup.
b
pull oxygen through the skin in order to continue working.
c
send signals to the brain telling it to shut the muscles down.
d
stop functioning properly, resulting in death.
a
start anaerobic respiration, producing lactic acid buildup.
The correct answer is:
a) start anaerobic respiration, producing lactic acid buildup.
When an individual exercises vigorously for more than 15 minutes, the muscle cells cannot obtain enough oxygen from the blood to meet their energy demands. In response, they switch to anaerobic respiration, a process that does not require oxygen but produces lactic acid as a byproduct. The accumulation of lactic acid can lead to muscle fatigue, soreness, and a burning sensation.
The correct answer is a. When an individual exercises vigorously for more than 15 minutes, the muscle cells are unable to obtain oxygen from the blood quickly enough. As a result, the muscle cells start anaerobic respiration, producing lactic acid buildup.
To understand why this happens, it is important to know a bit about how our muscles generate energy. During exercise, our muscles need a constant supply of energy to contract and perform work. The primary source of energy for muscle contractions is adenosine triphosphate (ATP).
There are two main pathways through which our muscles can generate ATP: aerobic respiration and anaerobic respiration. Aerobic respiration occurs when there is enough oxygen available to the muscle cells. It is a highly efficient process that breaks down glucose and fats to produce ATP, carbon dioxide, and water.
However, during intense exercise, the demand for ATP increases rapidly, and the oxygen supply to the muscles cannot keep up with the demand. This is because the respiratory and cardiovascular systems take a bit of time to deliver oxygen to working muscles. As a result, the muscle cells switch to anaerobic respiration.
Anaerobic respiration is a less efficient process that occurs in the absence of oxygen. It involves the breakdown of glucose to produce ATP and lactic acid. This process occurs quickly and provides a rapid but limited energy supply to the muscles.
The accumulation of lactic acid in the muscles leads to the sensation of muscle fatigue and a burning sensation. It can also result in muscle soreness after exercise. Once exercise intensity decreases or stops, the lactic acid is gradually removed from the muscles by the bloodstream and converted into glucose in the liver.
So, to summarize, during vigorous exercise, when muscle cells cannot obtain enough oxygen, they switch to anaerobic respiration, resulting in lactic acid buildup.