Human Biology Unit 2 Assignment
Carry out an experiment to measure the heart rate and ventilation rate before, during and after moderate exercise. Introduction:
I predict that during exercise the heart and respiratory rate (RR) will increase depending on the intensity of exercise and the resting rates will be restored soon after exercise has stopped. I believe that the changes are caused by the increased need for oxygen and energy in muscles as they have to contract faster during exercise. When the exercise is finished the heart and ventilation rates will gradually decrease back to the resting rates as the muscles’ need for oxygen and energy will be smaller than during exercise. Experiment:
1. To start with the experiment we measured the persons resting heart rate and respiratory rate where there was no strain on the muscles. We continued to check both pulse and respiratory rates at 30 second intervals during the course of exercise. 2. We decided to make the length of each consecutive exercise 30 seconds long. Between each session we allowed the student’s pulse and respiratory rate return to their resting rates, otherwise the results would not be fair if both rates were higher at the start of the exercise. 3. Throughout each exercise the student made sure that equal paces were maintained so that it would not affect the heart or respiratory rate in a different way. Immediately after exercise the subject sat down in a chair so that both the heart and respiratory rates could be taken. The pulse rate was measured first for 15 seconds, if we had taken the pulse rate for 1 minute the pulse rate would have slowed down. As soon as the pulse rate was taken we then took the respiratory rate for 15 seconds. We then waited for both rates to return to their normal resting rates before starting the next exercise.
Our experiment was about how the heart and respiratory rates are affected by exercise. Unless we use a stethoscope we cannot measure both rates directly. We measured the pulse rate on the carotid artery. This will keep the experiment fair because each heart beat set up a ripple of pressure which passes along the arteries. The ripple can be felt as a pulse as the artery’s muscular wall expands and relaxes. Measuring the pulse rate is measuring the subject’s hearts beats except there is minimal lapse between the beat and the pulse. The diastole and systole produce a very distinctive two tone sound which is very easily felt. So to make sure we do not count twice we will always count the first pulse of the two. (Boyle and Senior Pgs. 160 – 161) Tiffin (Northumberland College Notes Jan’12) Sources of Error:
The sources of error in this experiment that we would have to include are: * Subject being fit / unfit • Healthy / Unhealthy * Smoker / Non-smoker • On regular medication * Drinker / Non-drinker • Suffer from any illnesses * No ECG Monitor • Male / Female We have to make sure that we keep the same person throughout. This is because every person has a different diet, fitness level, weight, stature or is a different gender. All these factors affect a person’s heart or respiratory rate. If the person was changed during the experiment the results would not be reliable or fair. The subject’s resting heart and respiratory rates would be different and their body’s reaction to exercise would also be different. The pace of the subject will affect their heart and respiratory rates. They may start off at a quick pace, but go slower when they begin to tire. The subject must rest between each exercise so that all the lactic acid and CO₂ can be carried away. The tiredness of the student will affect the pace at which the subject performs their exercise. This is why it is crucial for fair results throughout the exercise. It is also necessary to allow the subject to recover before carrying on with their exercise....
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