Human Transport Systems: The Pulse Rate Experiment

Introduction

Background of the study

The cardiovascular system is a part of the human transport system. It consists of the heart, arteries, veins, and capillaries. It performs various functions especially when an individual is exercising (Turner, 2000, p. 309). Some of its functions include transporting oxygenated blood to the active muscles, transporting blood to the heart for oxygenation, transferring heat from other parts of the body to the skin to facilitate heat loss. The system also transports nutrients to the muscles and various tissues in addition to transporting hormones to target organs (Turner, 2000, p. 315).

During exercises, the demand for nutrients and oxygenated blood increases. In addition, an increase in the rate of metabolism contributes to high levels of waste products that should be transported to the excretory systems. The active muscles generate metabolic heat which should also be transported to the skin. To meet the elevated cardio-respiratory and metabolic demands, the cardiovascular system responds by altering the heart rate, stroke volume, blood flow, blood pressure, and cardiac output (Turner, 2000, p. 320).

There are various points where the pulse rate can be measured. Some of them include the temple, neck, top of the foot, back of the knees, and groin. In addition, the heart rate can also be measured directly from the heart by tying a pulse machine across the chest. Research studies conducted indicate that the normal pulse rate is about 60-120 beats per minute (BPM) for infants and children and 60-100 BPM for adults (Clausen, 2009, p. 779).

Aim

The report presents an account of the pulse rate experiment before and after a five-minute exercise on a running machine.

Scope

The report entails an account of the pulse rate experiment. It entails the methodology and the instruments/requirements used in conducting the study. In addition, the results of the experiment are outlined. The report provides an account of the effect of exercise on cardiac output, blood pressure, and blood distribution. It also reviews the role of the sensory receptors, the automatic nervous system, and hormones. Finally, an analysis of the changes observed during and after the exercise is conducted.

Requirements/Instruments

To measure the pulse rate before and after the exercise, the researcher should have a pulse meter. In addition, a running machine is required to enable the researcher to conduct the five-minute exercise.

Methodology

The experiment started by measuring the pulse rate at rest using the pulse meter tied across the chest to take direct measurements from the heart. This was followed by a five-minute exercise on the running machine after which the pulse rates were measured and recorded after every minute until the pulse rate returned to normal.

Presentation of Results

The data generated from the experiment was recorded in a table and the results are represented graphically as illustrated below.

A Table of Results

Before the Exercise During the Exercise After the Exercise
DURATION OF THE EXPERIMENT
(in minutes)
0 1 2 3 4 5 6 7 8 9 10
PULSE RATE
(in beats per minute, BPM)
64 69 95 119 141 145 119 87 73 67 64
A Graph of the Pulse Rate against the Duration of the Experiment
A Graph of the Pulse Rate against the Duration of the Experiment.

Analysis of Results

The results above indicate that the pulse rate increases gradually during the first few minutes of exercising. Later, the pulse rate increases steadily within the 2nd – 5th minute followed by a dramatic decrease from the 6th minute after the exercise until the normal rate is attained.

Discussions

The Effect of the Exercise on the Pulse Rate

Research studies conducted indicate that the heart rate can increase before the exercise begins mainly due to the anticipatory feedback which is a result of hormonal secretion. The anticipatory response is then followed by an elevated pulse rate which is equivalent to the intensity of the exercise (Clausen, 2009, p. 790). This state is maintained until the pulse rate reaches the maximum point which is approximately 145-160 BPM in normal individuals. However, if the intensity of the exercise remains constant, the pulse rate will eventually level off thereby reaching a steady-state (Clausen, 2009, p. 795).

During hot weather, the rate increases despite the activity rate remaining constant. This is a condition referred to as a cardiac drift that occurs as a result of elevated blood temperature. In the course of the exercise, delivery of oxygenated blood to the active muscles decreases, energy requirements increases while anaerobic respiration replaces aerobic respiration. This leads to the production of high levels of carbon dioxide (CO2) and lactic acid. The heart rate increases in response to the high levels of CO2 which need to be expelled from the body. After the exercise, the pulse rate begins to decrease gradually until it returns to its normal state. This is because the body begins to pay back the oxygen debt at rest thus decreasing the levels of CO2 and lactic acid (Clausen, 2009, p. 781).

The Effect of the Exercise on the Cardiac Output

Research studies indicate that during fortitude training, the cardiac output remains constant or decreases slightly. However, under strenuous exercise, the cardiac output increases steadily (Coyle et al., 2004, p. 95). This arises from the fact that stroke volume increases as a result of the maximal pulse rate experienced during the exercise. The same studies indicate that for a normal person at rest, the output is approximately 14-20 liters per minute while during training, the output increases to about 25-35 liters per minute. The maximum cardiac output can be as high as 40 liters per minute (Coyle et al., 2004, p. 95).

The Effect of Exercising on the Blood Pressure

In studies conducted on hypertensive individuals, both systolic and diastolic blood pressure decreases by a margin of 10 mmHg as a result of sub-maximal exercising. On the other hand, maximal exercising results in a significant fall in systolic pressure relative to resting individuals (Coyle et al., 2004, p. 97).

The Effect of Exercising on Blood Distribution

During exercises, there is an increment in the number of blood capillaries to compensate for the increased stroke volume. In addition, the blood capillaries become enlarged to increase efficiency in blood re-distribution and to attain an elevated blood flow. All these changes serve to increase the blood flow to the skin and the periphery (Coyle et al., 2004, p. 99).

The role of sensory receptors, autonomic nervous system, and hormones on bringing about the changes during and after the exercise

Results of the studies conducted indicate that the pulse rate increases before the commencement of the exercise due to the anticipatory response which is generated upon the release of the neurotransmitters, epinephrine, and norepinephrine (Turner, 2000, p. 336). Subsequent changes during exercising are attributed to the existence of a two-level control mechanism also known as the neurohormonal system.

The first phase involves three control mechanisms namely the feedforward coupling, the feedforward command, and the feedback reflex associated with the muscular mechanoreceptors (Turner 2000, p. 338). The three mechanisms help the body to maintain suitable respiratory and cardiovascular reactions towards the effects of the exercise. The second phase is dependent on the hormones which relay chemical errors to the brain through a standard response reflex system (Turner, 2000, p. 339).

The hormones can act either directly or indirectly on the target organs. Through their actions on the chemoreceptors, the hormones manage to bring about the appropriate ventilatory feedback during the exercise. In addition, hormonal responses help in coordinating cardio-respiratory changes with the increase in metabolic requirements, imbalances in fluid homeostasis, nutrient transportation, and thermoregulatory requirements (Turner, 2000, p. 340).

Conclusion

This report provides an analysis of the pulse rate experiment aimed at determining the pulse rates before and after a five-minute exercise conducted by the researcher. The report also covers the methodology and provides the results of the experiment. Subsequent discussions provide the effects of the exercise on the cardio-respiratory changes such as cardiac output, pulse rate, blood pressure, and blood distribution which are observable during the exercise. As noted from the discussions, the pulse rate increases to the same degree as the intensity of the exercise during training until a maximum is reached. At the end of the exercise, the pulse rate begins to decrease gradually until it returns to its normal rate.

Reference list

Clausen, J.P. 2009. Effects of physical training on cardiovascular adjustments to exercise in man. Physiological Reviews. Vol. 57, issue no.1, pp. 779-816.

Coyle, E., Hemmert, M. & Coggan, A. 2004. Effects of detraining on cardiovascular responses to exercise: role of blood volume.Journal of Applied Physiology. Vol. 60, Issue no.1, pp. 95-99.

Turner, D.L. 2000. Cardiovascular and respiratory control mechanisms during exercise: an integrated view. J. exp. Biol. Vol. 160, issue no.1, pp. 309-340.