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Effects of Exercise on Cardiac Output.

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Introduction

Sasha Caddy, 22/12/03 RM11. Effects of Exercise on Cardiac Output From the two graphs there are distinctive trends and patterns. In the first graph, which shows the averages of both male and female affected heart rates per minute according to the levels of activity performed, there is an average resting heart rate for both males (74 bpm) and females (78 bpm), there is then a slight rise when undergoing the mild exercise of walking: male (77 bpm), female (86 bpm), then there is a decrease in heart rate in both counts when resting again: male (74 bpm), female (79 bpm - the females average is nearly back to its original resting pulse rate). The average heart rates at anticipation are a higher and slightly steeper rise: male (87 bpm), female (93 bpm), than the mild exercise. Then finally when sprinting there is a much greater and steeper curved line as the heart rates both increased tremendously: male (151 bpm), female (142 bpm). However, the difference between resting and exercise is that when exercising, the heart's pulse rate is incredibly high compared to the resting heart rate where it is a lot lower. This is due to the body as a whole, using oxygen and glucose more quickly when exercising, so the blood must deliver it more rapidly, therefore the heart needs to pump a greater volume of blood each minute when sprinting than it does when resting. The male heart rate from resting to exercise has more than doubled, whereas the female heart rate has less than doubled the rate, this could be due to a number of reasons, such as the females were probably not running at a harder pace than the males, so there is a larger increase in the male's heart rate. Although, the difference between the male's and female's heart rate per minute throughout these levels of activity is that at first the female's resting heart rate is 4 beats per minute higher than the male's, this may be because the males have a higher level of fitness overall than females so their pulse rate is lower. ...read more.

Middle

This decrease in the stored ATP activates the enzyme which begins the further breakdown of the muscle glycogen into glucose, which is used to make more ATP. Carbon dioxide builds up in the skeletal muscle tissues resulted from the increased metabolic rate leading to the arterioles serving these active muscles to dilate causing an increase in blood flow through them. One of the cardiovascular system and respiratory system critical roles are to get rid of the heat produced by increased metabolism during exercise. To achieve this the increased blood flow to the skin results in direct transfer of heat to the environment as well as loss of heat during evaporation of sweat. Substantial heat is also transferred to the atmosphere in exhaled air during breathing. This increase in body temperature makes the tissues more sensitive to carbon dioxide. The continued rapid movement of the limbs stimulates stretch receptors in the skeletal muscles and tendons, which transmit impulses to the cardiovascular centre leading to a further increase in cardiac output. The chemoreceptors in the medulla, carotid artery and aorta bodies detects any changes in the level of carbon dioxide concentration in the bloodstream and responds by adjusting the ventilation rate. Anaerobic respiration may also occur in certain body cells sometimes deprived of sufficient oxygen. This occurs in the muscle cells, which need more oxygen during this strenuous exercise than the circulatory system can supply. Meanwhile, insufficient oxygen is delivered to the muscles to keep pace with their demands, resulting in the muscles respiring anaerobically with the process of lactic acid being formed. When the muscle cells respire anaerobically they build up an oxygen debt. This lactic acid gathers during the sprint and afterwards it is oxidised by way of the Krebs cycle or by circulation to the liver where it is converted back to glycogen, oxygen is needed for this. Immediately after the sprint, the muscles stop working and relax, the body begins to repay the metabolic debts built up during the sprint and repairs any damage done, the heavy panting (a faster and deeper breathing) ...read more.

Conclusion

* Anyone participating in the experiment may have been just recovering or suffering at that time from a fever or another illness e.g. cold, which influences the heartbeat resulting in a faster heart rate than 'normal'. * Between the time the pulse rates were taken at anticipation and the time taken to start the exercise, there would have been a further increase in the heart rate. The limitations that could adjust the reliability of this experiment is that firstly, I think the experiment should be carried out mid-morning e.g. 10a.m, or mid-afternoon e.g. 2p.m, so that the amount of food eaten in the morning or at lunch will not have much of an affect on the results. To be able to control the subject prior to the experiment, I think that possibly the level of exercise should be restricted or more resting time should have been allowed in order for our heart rates to return to 'normal' incase of any unusually high heart rates. For clothing, I think that it may be best to wear shorts, trainers and t-shirts so that there are no restrictions, it will also lead to a better set of results. I think that even though we were told the distance we had to run, it wasn't properly controlled, to overcome this problem I think that a big improvement would be to carry out the experiment using a running machine. This will enable a set distance and it will also overcome the problem of everyone not running at the same pace, as the running machine will be at a set pace. Also the pulse rate may not have been accurate and reliable, a solution to this could be by using a polar heart rate monitor, where the electrodes can be attached to the chest so that the heart rate is much more accurate and is monitored throughout the experiment. In this experiment there were no anomalous results which can be shown from the two graphs. ...read more.

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