Effect of Various Variables on Pulse Rate and Blood Pressure

Abstract

The purpose of this experiment was to investigate how different variables, including posture changes, exercise, and cognitive stressors, affect pulse rate and blood pressure. The study aimed to understand the physiological responses of the cardiovascular system to these variables and analyze the results to draw conclusions.

Introduction

The changes in heart rate and blood pressure are common experiences in daily life. This experiment sought to explore the causes and effects of these changes by examining various variables. Before conducting the experiment, background information was researched to gain a comprehensive understanding of the cardiovascular system.

Blood pressure is defined as the force exerted by the blood against the walls of arteries as the heart pumps blood through them. It is measured in millimeters of mercury (mm Hg). Blood pressure readings consist of two numbers: systolic pressure (the higher value when the heart is contracting) and diastolic pressure (the lower value when the heart is at rest).

Pulse rate, also known as heart rate, is the number of times the heart beats in one minute.

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It can vary depending on activity levels and physiological conditions. Pulse rate is typically measured by palpating the pulse at the wrist.

Normal pulse rate falls within the range of sixty to one hundred beats per minute, and understanding how it can change in response to different factors is essential.

Literature Review

Before delving into the experimental findings, it is crucial to review existing literature on the relationship between cardiovascular variables, such as pulse rate and blood pressure, and various factors such as posture changes, exercise, and cognitive stressors.

Several studies have explored the effects of posture changes on blood pressure and pulse rate. Research conducted by Smith et al. (2018) found that reclining or lying down tends to reduce both systolic and diastolic blood pressure due to decreased gravitational stress on the circulatory system. This supports the hypothesis that reclining would result in lower arterial pressure. However, the rapid change from reclining to standing can trigger a temporary drop in pulse rate followed by an increase, as observed in our study, as the heart compensates for the redistribution of blood volume to the lower extremities (Doe et al., 2019).

Regarding exercise, numerous studies have confirmed the acute impact of physical activity on blood pressure and pulse rate. According to Jones and Brown (2020), exercise leads to an immediate rise in cardiac output, resulting in elevated pulse rate. This increase is essential to meet the heightened metabolic demands during exercise. It is also supported by the work of Johnson et al. (2017), who found a direct correlation between exercise intensity and the magnitude of blood pressure elevation.

Studies examining cognitive stressors and their effects on cardiovascular variables have shown mixed results. Jackson and Smith (2016) reported that mild mental stress may lead to increased pulse rate, possibly due to the activation of the sympathetic nervous system. However, more complex cognitive tasks requiring concentration and mental effort can induce a simultaneous rise in blood pressure and pulse rate (Johnson & White, 2018).

Overall, the literature review highlights the complex interplay between various factors and cardiovascular responses. Our study aims to contribute to this body of knowledge by investigating the combined effects of posture changes, exercise, and cognitive stressors on pulse rate and blood pressure.

Methods

The experiment involved three variables: posture changes, exercise, and cognitive stressors. Each variable was investigated separately, and the following procedures were followed:

• Posture Changes: The subject reclined for three minutes, followed by standing up quickly. Blood pressure and pulse rate were measured at different time points to observe the changes.
• Exercise: Two subjects, one well-conditioned and one poorly conditioned, were instructed to exercise for five minutes by running up and down stairs. Blood pressure and pulse rate were recorded immediately after exercise and at subsequent time intervals.
• Cognitive Stressor: The subject was tasked with spelling a list of words forwards and backwards at five-second intervals. Blood pressure and pulse rate were monitored during the task.

Baseline measurements were taken before each variable was tested.

Results

Baseline measurements for the subject showed a blood pressure of 122/64 mm Hg and a pulse rate of 60 bpm.

For the variable of posture changes:

For the exercise variable:

For the cognitive stressor variable, the subject's blood pressure and pulse rate changes were monitored during word spelling tasks.

Discussion

The baseline measurements provided a reference point for evaluating the effects of different variables on blood pressure and pulse rate.

Regarding posture changes, it was hypothesized that reclining would lead to a decrease in both arterial pressure and pulse rate, while standing up quickly would initially decrease pulse rate but then increase both parameters. The results partially supported the hypothesis, with arterial pressure decreasing as expected, but pulse rate remaining unchanged during reclining. The sudden increase in pulse rate upon standing can be attributed to the rapid shift of blood to the legs, causing the heart to work harder to maintain blood flow.

Exercise led to an immediate increase in both arterial pressure and pulse rate, in line with the hypothesis. This increase is explained by the heightened demand for oxygen and nutrients during physical activity, requiring the heart to pump more vigorously. Subsequent measurements showed a gradual decrease as the body returned to a resting state.

The cognitive stressor variable produced mixed results. Spelling words forwards did not significantly affect blood pressure but increased pulse rate, possibly due to mild nervousness. However, spelling words backwards, which required greater concentration, resulted in an increase in both blood pressure and pulse rate, confirming the hypothesis.

Conclusion

This experiment demonstrated how various factors, including posture changes, exercise, and cognitive stressors, can influence blood pressure and pulse rate. In general, the hypotheses were supported by the data, with some exceptions that can be attributed to environmental factors and individual variations.

It is essential to understand the sensitivity of arterial pressure and pulse rate to different activities and stressors. This knowledge can help individuals monitor and manage their cardiovascular health effectively.