Video TranscriptWhich of the following best describes what is meant by oxygen debt? (A) An oxygen debt is the amount of oxygen lost in a 24-hour period. (B) An oxygen debt is the amount of oxygen required after exercise to remove the lactic acid from the body. (C) An oxygen debt is the number of breaths taken during a period of intense exercise. Or (D) an oxygen debt is the amount of oxygen taken in by the muscles during exercise. Show This question asks us about oxygen debt, which is a term used to describe a phenomenon that occurs during a specific type of cellular respiration. You have probably heard the word debt before in terms of finances, when someone spends more than they are able to immediately pay and so they owe money. Let’s review what this means in terms of oxygen and cellular respiration. Cellular respiration is a process that cells can use to produce high-energy compounds like ATP by breaking down sugars such as glucose. ATP can then be quickly broken down in cells to release energy whenever it is needed. The main form of cellular respiration that is carried out by cells is called aerobic respiration, which reacts glucose with oxygen to produce carbon dioxide, water, and several molecules of ATP. Sometimes, for example, when we carry out intense exercise, our cells require so much energy in the form of ATP that the amount of oxygen inhaled for aerobic respiration is not sufficient to meet the body’s energy demand. In these scenarios, anaerobic respiration can take place in the absence of oxygen. In fact, the word “anaerobic” derives from the Greek words that mean life without air. In humans, anaerobic respiration breaks down glucose to produce a substance called lactic acid, so it is sometimes called lactic acid fermentation. Too much lactic acid can be toxic to human cells, so it must be broken down into a less toxic form. It is commonly believed that a buildup of lactic acid is linked to the immediate muscle pain you may feel during intense exercise. The organ that detoxifies lactic acid is the liver, which has the option of converting lactic acid back into glucose provided that there is sufficient energy available to do so. Alternatively, the liver can break down lactic acid by reacting it with oxygen to produce carbon dioxide and water, which you might have noticed are the same products as aerobic respiration. The amount of additional oxygen that is necessary to remove lactic acid from the body is called oxygen debt. Now we can answer our question, which asks us to select the answer that best describes what is meant by oxygen debt. We know that the correct answer choice must be (B). An oxygen debt is the amount of oxygen required after exercise to remove the lactic acid from the body. When we are relaxing, there is a relatively low demand for energy because we aren’t moving. However, the demand for energy increases when we exercise, as there is more muscle contraction. Our bodies have to respond to this increased demand for energy. The Effects of ExerciseWhen we exercise, we have to use our muscles much more than usual. This means that the rate of cellular respiration must increase. As aerobic respiration requires oxygen, we will need to get more oxygen and glucose to our muscles. To achieve this, there is an increase in:
Although, sometimes we still cannot supply enough oxygen to the muscles, especially if we are exercising hard. So instead, anaerobic respiration takes place in the muscles. Measuring the effects of ExerciseThe two main ways we can measure the effects of exercise on the body:
Oxygen DebtWhen we are doing vigorous exercise, our cells may need to use anaerobic respiration, which is far less efficient than aerobic respiration. But if there isn’t enough oxygen, then the efficiency doesn’t matter because it’s our best option. However, the main problem with anaerobic respiration is that the oxidation of glucose is incomplete. This causes lactic acid to build up in the muscles. You might recognise this from the burning sensation you feel in your muscles during vigorous exercise.
As soon as we finish exercising, our liver gets rid of the lactic acid by reacting it with oxygen. So, the more lactic acid is built up, the more oxygen will be required to get rid of it. This is called oxygen debt. We are paying back this debt when we still breathe heavily after we have stopped vigorous exercise. The lactic acid is transported from the muscles to the liver, where it is converted to glucose. What is oxygen debt in the body?The amount of oxygen required to remove the lactic acid, and replace the body's reserves of oxygen, is called the oxygen debt. When someone who has been exercising pays back an oxygen debt, it can take from a few hours for normal exercise, to several days after a marathon.
What substance is produced during oxygen debt?Oxygen debt After exercise, the lactic acid has built up and caused an extra need for oxygen – called the oxygen debt. Lactic acid Chemical produced by the incomplete oxidation of glucose (anaerobic respiration).
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