Experiment to Measure the Heart Rate and Ventilation Rate Before, During and After Moderate Exercise

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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.

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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.

Fair Testing: 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 CO? 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. We must measure the subject’s pulse and respiratory rates in the same position as we did their resting rates. If we do not, we would not get accurate results. If we were to take the subject’s pulse rate standing up the heart rate would rise because the muscles are working to keep the subject upright. The heart rate would have to work harder in order to keep their muscles working.

We decided to measure the subject’s pulse and respiratory rates whilst sitting down because there would be no additional stress on their heart, which would increase their heart rate. Their heart rate should also return to its resting heart rate due to the decrease of muscle use. I have placed the results from our experiment in form of a table and will use the average results to form a graph. I have also prepared a graph to show the results throughout the exercise. As the results show the highest increase in the pulse rate is in exercise 2 where the pulse rises by 44 BPM and the respiratory rate by 8 RR.

Thereafter it continues to rise by 40 BPM and 8 RR. We did however experience a higher respiratory rate in the second lot of results in exercise 4 where the respiratory rate did rise by 12 RR. During exercise, the subject’s heart rate, systolic blood pressure, and their cardiac output (the amount of blood pumped per heart beat) all increase to maintain a state of balance, known as homeostasis. Homeostasis is a self-regulating process by which the human body maintains internal stability under fluctuating environmental conditions.

Blood flow to the subject’s heart, their muscles, and their skin increase. Sweat glands secrete a salty solution that evaporates from the skin, taking heat with it. Their body’s metabolism becomes more active, producing CO? and H+ in the muscles and consequently lowers PH. The subject breathes faster and deeper to supply the oxygen required by this increased metabolism. With strenuous exercise, their body’s metabolism exceeds the oxygen supply and begins to use alternate biochemical processes that do not require oxygen. These processes generate lactic acid, which enters their blood stream.

The subject’s cardiovascular system, their breathing system and their muscles work in conjunction with each other in order to perform their tasks more efficiently. A vital process of exercise is respiration (the production of energy). Principally, respiration is the breakdown of oxygen and glucose into carbon dioxide, water and ATP. Aerobic respiration requires oxygen and has the ability to break down both fatty acids and glucose. Anaerobic respiration takes place when there is a lack of oxygen, a lactate is formed and fatty acids cannot be broken down. (Boyle and Senior Pgs. 62, Pg. 215 and Pg. 222) Tiffin (Northumberland College Notes Feb’12) Glucose + Oxygen Carbon Dioxide + Water – C6H12O6 + 6O? —–>6CO? +6H? O+Energy Oxygen is taken into the subject’s lungs and then diffused into their bloodstream. Cells need oxygen to respire so more oxygen needs to be transported to muscle cells. This then causes the subject to breathe more deeply. Their intercostal muscles (muscles in between the ribs) contract up and out, moving the subject’s ribs and diaphragm up and out (a sheet of muscle at the bottom of the thorax, chest cavity).

This increases the subject’s space available in their lungs for air to fill. More air in the lungs means there is more oxygen, so that more oxygen can be diffused into the bloodstream. The number of the subject’s breaths increases too, to maintain a high concentration gradient. Heart rate also needs to increase to keep their blood flowing through the lungs. The subject’s heart and respiratory rates rise because during exercise, their cell respiration in the muscles increase, so the level of carbon dioxide in their blood rises.

Carbon dioxide is slightly acid, the brain detects the rising acidity in the subject’s blood, their brain then sends a signal through the nervous system to their lungs to breathe faster and deeper. Blood flows from areas of high pressure to areas of low pressure. The area of high pressure is the pressure created by the contraction of the subject’s ventricles, which forces blood out of their heart into the aorta. Resistance is caused by friction between the blood and the vessel walls. Gaseous exchange in the subject’s lungs increases allowing more oxygen into their circulatory system and removing more carbon dioxide.

The subject’s brain then sends a signal to the sinoatrial node (SAN) to make the heart beat faster. Heart rate is controlled by the SAN. The subject’s rate goes up or down when the SAN receives information via their two automatic nerves. (Boyle and Senior Pgs. 160-162) Tiffin (Northumberland College Notes Jan-Feb 2012) • Their sympathetic or accelerator nerve which speeds up their heart rate. The synapses at the end of this nerve secrete noradrenaline. • Their parasympathetic or decelerator nerve, a branch of their vagus nerve, slows down their heart rate. (Boyle and Senior Pg. 162)

A negative feedback system controls the subject’s level of carbon dioxide. During exercise, their blood level of carbon dioxide starts to rise. This is detected by chemoreceptors situated in three places: the carotid artery, the aorta and the medulla. Nerve impulses travel from these receptors to the subject’s cardiovascular centre. In response, their cardiovascular centre sends impulses down the sympathetic nerve to increase the subject’s heart rate. Their heart rate returns to normal after the cardiovascular centre sends impulses down the parasympathetic nerve once carbon dioxide levels have dropped. Boyle and Senior Pg. 162) Tiffin (Northumberland College Notes Feb’12) At rest During Exercise These images illustrate the alveoli and a red blood cell during rest and activity. This is the site where the red blood cells exchange carbon dioxide molecules for oxygen molecules to transport throughout the body. Notice the increase of both molecules as activity increases. (Zygote Media Group, Inc. ) The heart’s natural pacemaker – the SA node – sends out regular electrical impulses from the top chamber (the atrium) causing it to contract and pump blood into the bottom chamber (the ventricle).

The electrical impulse is then conducted to the ventricles through a form of ‘junction box’ called the AV node. The impulse spreads into the ventricles, causing the muscle to contract and to pump out the blood. The blood from the right ventricle goes to the lungs, and the blood from the left ventricle goes to the body. (SADS Sudden Arrhythmic Death Syndrome) Conclusion: I have concluded, with the evidence provided in the graphs and table, in which the pulse and ventilation rates do increase during exercise.

Overall, the results confirm the initial prediction that the heart and ventilation rates increase during exercise and return to normal level shortly after exercise has been completed. Heart and ventilation rates increased during the high intensity exercise to feed the body’s need for more oxygen and energy have been decreasing gradually immediately after exercise has finished as the muscles did not need more energy than usually. It is important to take into account each individual’s personal health, fitness and lifestyle when considering the effects of exercise. Generally, the fitter the individual, more quickly the resting rate is achieved.