IGCSE Biology 0610 - 8.2 Transport in Humans

Objective: Investigate and state the effect of physical activity on pulse rate.

Introduction

The human circulatory system is responsible for transporting blood, which carries oxygen, nutrients, hormones, and waste products throughout the body. A key indicator of cardiovascular health is the pulse rate, which is the number of heartbeats per minute. Physical activity significantly impacts the pulse rate due to the increased demand for oxygen and energy by the muscles.

The Heart and Circulation

The heart is a muscular organ that pumps blood around the body. Blood travels through a network of blood vessels, including arteries, veins, and capillaries. Arteries carry blood away from the heart, while veins carry blood back to the heart. Capillaries are tiny blood vessels that connect arteries and veins and facilitate the exchange of substances between the blood and the body's tissues.

How Physical Activity Affects Pulse Rate

During physical activity, the body's metabolic rate increases. This means that muscles require more oxygen and energy. To meet this increased demand, the heart needs to pump blood faster. This results in an increase in the pulse rate.

The relationship between physical activity and pulse rate is generally linear – as the intensity of exercise increases, the pulse rate also increases.

Factors Influencing Pulse Rate During Exercise

• Intensity of Exercise: Higher intensity activities lead to a greater increase in pulse rate.
• Fitness Level: Individuals with a higher fitness level tend to have a lower resting pulse rate and a smaller increase in pulse rate during exercise compared to less fit individuals.
• Age: Pulse rate generally decreases with age.
• Emotional State: Stress and excitement can temporarily increase pulse rate.
• Body Position: Standing upright allows for more efficient blood return to the heart, potentially leading to a lower pulse rate compared to lying down.

Investigating the Effect of Physical Activity on Pulse Rate

An investigation to determine the effect of physical activity on pulse rate typically involves measuring the pulse rate at rest and then measuring the pulse rate at various intensities of exercise. The pulse rate is usually measured by counting the number of heartbeats for a specific period (e.g., 15 seconds) and then multiplying by 4 to get the beats per minute (bpm).

Data Analysis and Presentation

The collected data can be presented in a table and a graph. The table would show the pulse rate at different stages of exercise. The graph would typically have time (or intensity of exercise) on the x-axis and pulse rate on the y-axis. The trend in the graph should show an increase in pulse rate with increasing intensity of exercise.

Example Data Table

Stage of Exercise	Time (seconds)	Number of Beats	Pulse Rate (bpm)
Resting	15	8	48
Light Walking	15	32	192
Moderate Jogging	15	76	456
Running	15	120	720

Conclusion

The results of an investigation into the effect of physical activity on pulse rate would demonstrate a clear positive correlation – as the intensity of exercise increases, the pulse rate also increases. This is because the body needs to deliver more oxygen and nutrients to the working muscles, requiring the heart to beat faster.

Further Considerations

It's important to note that individual responses to exercise can vary. Factors such as fitness level and age can influence the magnitude of the increase in pulse rate. Monitoring pulse rate during exercise is a valuable way to assess cardiovascular fitness and ensure that exercise intensity is appropriate.