Oxygen + Glucose → Carbon Dioxide + Water + Energy
An increase in the pulse rate of both the students shows that there is an increase in their blood pressure, indicating an increase in their heart rate to get more oxygen to their tissues. To do this the respiratory rate has to increase to get more oxygen. In aerobic respiration students are using glucose with the oxygen to give them more energy. If they do not have oxygen in respiration then it is called anaerobic respiration, this is our short term energy system for when our muscles are working harder for a short amount of time e.g. Sprint runner. As we do not have oxygen in this we use our body stores of Adenosinetriphosphate (ATP) to give us energy. However this runs out after a while and we use Adenosinediphosphate (ADP) and glycogen in our body to create more this gives a waste product of Pyruvic acid and if oxygen is not put into this then we have the final product of lactic acid. In the first three minute of exercise both the students use initial energy from Creatine Phosphate (CP), from then till about five/six minutes they used anaerobic system and from then on they used their aerobic system. Their creatine phosphate does not use oxygen as it is fuel that our body already has, if they go over the creatine phosphate supply they go into anaerobic respiration. This is our short term energy supply. Also known as our lactic acid system. It uses ATP to give us energy this energy gives us ADP which uses glycogen to give us ATP and pyrovic acid and as they have no oxygen this turns into lactic acid which can lead to tiredness, muscle cramp and fatigue. After this we need to payback the oxygen debt that we have to replace oxygen stores in our body. However if we do not stop at this we go into aerobic respiration which needs oxygen as it is our long term energy system and has to repay the oxygen debt. In aerobic respiration ADP plus glycogen which is stored glucose gives us ATP and pyrovic acid as the waste product. As we have oxygen it does not lead to lactic acid it removes it.
From the graphs of both the students I can see that for the first three minutes the rate of increase of heart beats are steady and constant because both the students were using creatine phosphate which was giving enough energy to carry on. They were using this as fuel which the body already had. Between the 4/5th minute student A went over the creatine phosphate supply and went into anaerobic respiration which can be seen on the graph, that the heart beats of student A has increased at a faster rate. At the start it was a steady 5-6 beats per minute increase but as it went in to the 4/5th minute the difference started to increase from 5 to 18 which indicates that Student A has gone into anaerobic respiration his heart beat per minute has increased but, towards the 8/9th minute the rate of increase of the heart beat has decreased, which can be seen on the table, from 11 to 5 b.p.m which suggests that student A is now respiring aerobically and the body is repaying the oxygen debt which occurred during anaerobic exercise.
However, student B’s heart rate is increasing at a steady rate in whole of the experiment. Even though the student B has a steady rate of increase and it went into anaerobic and aerobic respiration just like Student A but, student B only went up to 7 minutes of exercise which suggests that student B is less fitter than the student B. It might be due to the following factors:
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Weight: Student A is less heavier than Student B which makes him more fit to go up to 9th minutes and student B is more heavier and only went up to 7 minutes. This shows that weight affects the way they perform in an exercise.
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Age: Student A might be younger than student B which makes Students A’s cardiac vascular endurance more than student B, which enabled Student A to go on for longer time.
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Sex: student A might be a male and student B might be a female. Males are generally have a larger heart and lungs and this helps them because more oxygen and blood can be transported around the body, which made student A to go on for longer time. Student B might be a female as females have more body fat than males which puts extra strain on the heart, muscles and joints so student B didn’t go on for longer time.
- As the process of the whole experiment was repeated in the next lesson to get the second sets of results, between this period of starting the exercise again student A might have had a carbohydrate snack which replaced his depleted energy therefore he/she went on exercising further than the student B
To start with student A’s heart beats per minute was lower than student B, which indicates that student A is fitter.
I will now calculate the cardiac output for both the students. Cardiac output is the volume of blood pumped by the left ventricle in a given time. When the body is at rest the stroke volume of an adult is 4.9 dm3/min and during exercise it rises to 30 dm3/min. It is usually measured in dm3 min-1 and depends upon two factors:
- The heart rate
- The stroke volume (how much blood is pumped out by the left ventricle at each beat).
The formula used to calculate the cardiac output is:
Cardiac output= heart rate x stroke volume
Here is the cardiac output of both students in their resting position:
Student A= 76 x 4.9
= 372.4 dm3min-1
Student B= 81 x 4.9
= 396.9 dm3min-1
Now I will calculate their cardiac output during exercise. During severe exercise output of an adult human rises to 30 dm3 min-1 and pumping of blood requires considerable and sustained energy.
Student A= 168 x 30
= 5040 dm3 min
Student B= 163 x 30
= 4890 dm3 min-1
From these calculations I can see there is an increase of 7% of cardiac output in student A and 8% in student B which means student A’s heart is working less faster than Student B indicating that Student A is fitter. This increased cardiac output also proves that during strenuous exercise due to the increase in the heart beat per minute the stroke volume of blood pumped by the left ventricle was more to cope with the demand of oxygen during exercise.
Conclusions:
Effects of exercise on the heart is that during exercise our bodies demand for oxygen increases and the rate of ventilation increases in order to absorb more oxygen at the gaseous exchange surface (lungs). To be effective, the rate at which blood carries oxygen to the muscles must also be increased. Therefore, the cardiac output can rise from 5 dm3 at rest to a maximum of 30 dm3 during very strenuous exercise. This is achieved when the heart rate increases from 70 beats per minute to 190 beats per minute and the stroke volume from 80 cm3 at each beat to 110cm3.
The other major effect of exercise on the body is redistribution of blood during exercise. Vasodilatation occurs in arteries serving the muscle involved in exercise to increase their oxygen supply. The percentage of blood to these muscles can increase from 13% at rest to 66% during exercise. This extra blood must be taken from the parts of the body that can temporarily exist with a limited supply. These parts include intestines and liver. It is important however to maintain the blood supply to the other vital organs such as the heart, kidney and brain as they need to operate normally with no loss of function.
The skin must also have an increased supply of blood to allow the heat generated during exercise to be lost thereby prevent a dangerous rise in temperature. The percentage of blood supplied to the skin may double from 5% to 10% during exercise.
Evaluation:
Although I believe this experiment has produced fairly valid results, I am not sure that the information provided was particularly accurate. For instance, I cannot be sure that the step-up exercise was done at the same rate throughout the experiment. Also, I am not sure how many seconds interval rest was taken in between by student A and B and if it was kept exactly to that timing. On the table first result for Student A does not show the b.p.m. at the 9th minute, as he has shown it in the second result column, it does not give me a fair average as I had to divide it by one instead of two.
If I were doing this experiment myself I would have to look closely at the method of exercising used by student A and B. I think that exercising on a piece of equipment like a running machine would produce more accurate results because I would be able to guarantee that the exercise remained constant throughout this experiment.
Finally, an actual ‘pulse-meter’ might have helped the experiment to be more accurate. This is simply strapped round the chest of the exercise and it measures your current heart rate. I believe that this would produce a more accurate heart rate and it would not be necessary to have breaks during the exercise.
