The oxygen that is now in the blood stream will now be transported to all the cells of my body so that it can combine with glucose to release energy. This shows that when I exercise as I breath in the oxygen from the atmosphere is actually being used to help the cells in my muscles respire.
Mitochondria are found in greater numbers in fast respiring cells such as muscles which are doing this when I exercise, this is because they are the site of aerobic respiration. They absorb glucose and oxygen and provide the energy releases in my muscle cells. So, as the length of exercise increases the more oxygen they will need resulting in me breathing at a quicker pace.
Glucose that is used during aerobic respiration is obtained from the food we eat. Amylase from the pancreas, salivary glands and small intestine breaks down starch to sugar (glucose) which then travels through the digestive system into the small intestine where it diffuses from the villi (small finger – like projections which have an excellent surface area) into the blood stream. Active transport can be used here, which is when substances are absorbed against the concentration gradient.
The red blood cells that transport the oxygen from the lungs to the cells contain large quantities of haemoglobin, combined with oxygen form oxyhaemoglobin. The blood stream, which also transports the glucose from the small intestine to the cells in the muscles. Glucose is carried by plasma which is a straw coloured liquid. Plasma also transports carbon dioxide from the organs to the lungs so it can be breathed out. Water passes into the blood and is lost as sweat or urine.
Once the energy is released in the muscle cells they can contract. The longer I exercise for the more oxygen and glucose I will need for this energy to be released.
Aerobic respiration is a very efficient method of producing energy, and one molecule of glucose can provide twenty times as more energy as anaerobic respiration. They only draw back is that it doesn’t release it as quickly.
The system that is used to transport the oxygen and glucose is called the circulatory system. It carries blood from the heart to all the cells of the body. The heart is the pump of this system. As I exercise for longer my muscles will respire at a faster rate, so the heart has to pump the blood round faster so the cells can respire quicker and get rid of waste products quicker as well.
This means that the pulse rate felt in my neck will beat faster because of the heart having to pump the blood around my body at a quicker speed. The link between carbon dioxide levels in my blood will trigger the heart to pump faster. Carbon dioxide is normally present in the air at 0.05% by volume, any increase above this level results in accelerated breathing and increased heart rate.
But of course my heart will only stretch so far, so this is why there should be a maximum level. Breathing rate can only increase to a certain level. Sweat will control my body temperature, which if it becomes too high would begin to de- nature enzymes. Because the arteries are pumping blood quickly to your face this will result in it becoming pink. Skin capillaries dilate so that extra heat from the blood can radiate away and cool the body.
However, aerobic respiration is not the only way that cells respire. Anaerobic respiration can also take place in releasing energy. This happens when the muscles are working so hard that the lungs and bloodstream cannot deliver enough oxygen to respire the available glucose aerobically. Therefore the glucose can only be partly broken down, releasing a much smaller amount of energy, and lactic acid as a waste product. It can only operate for a short time. If my exercise in this investigation goes on for too long then I would begin to feel fatigued and result in an oxygen debt, this is due to a lactic acid built up and not enough oxygen reaching the muscle cells. This causes my muscles to stop contracting efficiently. It only produces one twentieth as much energy as aerobic respiration but does this much quicker over a shorter period of time.
Glucose → lactic acid + a bit of energy
Plan
The apparatus I will use are:
- A skipping rope
- A stop clock
- Trainers
I will begin my investigation by getting a friend to take my pulse rate at resting, to do this I will use my first and second finger and not my thumb as it has its own pulse and could affect the accuracy of my reading. This will be done so that after each period of time I do, I will know when it is suitable to do the next length of exercise. Otherwise it would not be a fair test.
Next I will skip consistently for 1min the rest and skip for two minutes. I will then repeat this for the consecutive numbers until I am skipping for 5 minutes. It may not be very accurate if my friend takes my pulse rate for 1min each time because the beats per minute might decrease by the end. Therefore I will get her to count them for 30 seconds and then double the result, this may prove to result in more reliable results. I will repeat this and then find an average.
I will make sure that I use the same skipping rope so that one is not heavier than the other, making the results different. Let the same friend take my pulse rate, and make sure it is at resting level before each period of exercise, otherwise there will be results that are not accurate because my pulse rate was already high before I actually did the exercise. I will make sure that the same person times the amount of time I do each period of exercise for. I will use the same surface in the same room.
To In order to make sure that this practical is safe I will be aware of anybody around me and wear trainers to prevent injury. The floor will also have to be flat.
Preliminary Practical.
Resting Pulse rate: 89(BPM)
Results
Resting – 90 BPM
I did have to repeat some inaccurate results. These were 1.5mins and 2mins.
I notice that as I increased the amount of exercise that I did, my pulses rate increased also. My pulse rate increased at a steady rate, roughly going up around 7 BPM for the first few times then more as the time increased. I am not sure why this is, as there seems to be no immediate explanation.
‘The length of exercise’ has influenced my results. By increasing the length that you exercise for increases your pulse rate (BPM). This means that the more exercise that is done the faster the heart has to pump the blood around the body so that it can transport oxygen to the muscle cells and waste products from them. This is what causes the increase in heartbeat (pulse rate)
This has affected my results because I am able to see that as I increased the length of exercise the pulse rate also increased.
The graph has a distinctive shape. It increases steadily then becomes horizontal, showing the steady pulse rate once it has reached its maximum level.
My results fit in with my prediction. I was breathing more deeply therefore taking in more oxygen. As I was using more energy the muscle cells needed more oxygen to respire. The heart pumps the blood faster so that these cells can get the required amount of oxygen, and also get rid of waste products. This gave me a faster pulse rate. It is important for the cells to get rid of carbon dioxide (a waste product) because it is toxic to us and therefore would cause cell damage resulting in cramp if not taken away from the cells and breathed out. It is breathed out by process of gaseous exchange, which is the process of obtaining oxygen and getting rid of C02. This gaseous exchange happens at a respiratory surface, so the heart pumps the blood around the body faster so that diffusion can occur faster. This is known as respiration and it is the process of converting glucose to energy.
At 1 minute I can see that my pulse rate had increased from 89 (BPM) to 116.5 (BPM) this shows that as I increased the exercise my pulse rate also increased. When the length of exercise increased to 5.0 minutes I begin to see a change in the results, before the pulse rate had been increasing steadily as the length did. But at 5.5 minutes the pulse rate remained the same as 5.0 minutes (187 BPM)
These results reinforce the prediction I had made, which was that the pulse rate would increase to a maximum level then continue at that level. This is exactly what happened. The reason for this is that my heart will only pump to a certain extent or level and then will level off at a continuous rate. The exerciser did not experience any cramps at this point which indicates she was respiring an aerobically.
Evaluation
I did not have any anomalous results e.g. 2 minutes did not have a higher pulse rate result than 3 minutes. However, 1.5 mins had a higher BPM than 2 mins so they were repeated, and the more satisfactory results recorded.
Although I managed to produce quite consistently good results I do think that this investigation was not that accurate. By looking at my repeated results I can see that they are quite consistent but I do feel they could have been better. The repeated results were all very close which showed reliability .
My results are definitely accurate enough to be able to define a conclusion. I can see that the longer the period of exercise I did, the higher the pulse rate went up to.
There are many things that I think could have made this investigation inaccurate. The intensity of exercise that I did may not have always been consistent, therefore sometimes I could have been skipping a lot faster than other times, making my pulse rate adjust to this. Also when my friend took my pulse rate at each interval, it is possible that she may have missed out beats, especially when it got to the longer times such as 5.5 minutes. This also could have affected my results. I did keep all the other key factors the same though so there was not anything that could have made it an unfair test.
I think that to overcome the problem of not being able to know exactly how intense I was exercising, it may have been a lot more accurate to have used a piece of equipment from a gym, such as a walking machine, this would have guaranteed that I was exercising with the same intensity each time. With the problem of taking my pulse rate I think that I could use a pulse monitor which is specialised in doing this, that would have really given better readings.
To look further into this key factor, I could try doing the experiment with different types of exercise. Then I could have found an average from them all to draw a very accurate conclusion about the relationship between length of exercise and pulse rate. I could also take my pulse rate with specialised equipment in different places on the body such a chest and wrist.
An obvious improvement on this investigation would be to have repeated it three times and then found an average. This would have meant that any anomalous results could have been not included in the average. Repetitions increased the reliability of my results.