The volume of blood that the heart pumps with every beat is known as the stroke volume. Stroke volume can be used to indicate fitness level. The table gives information about the stroke volume, heart rate and cardiac output of an athlete at rest and during exercise. | athlete | stroke volume / dm³ | heart rate / beats per minute | cardiac output / dm³ min⁻¹ | |------------|----------------------|-------------------------------|------------------------------| | at rest | 0.1 | 53 | 5.3 | | during exercise | ? | 182 | 30.4 | (a) Calculate the stroke volume of the athlete during exercise. answer = .............................. dm³ (b) Explain why it is important that the cardiac output of the athlete increases during exercise. (c) Describe how the circulatory system transports substances around the body.

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The volume of blood that the heart pumps with every beat is known as the stroke volume - Edexcel - GCSE Biology - Question 4 - 2012 - Paper 1

Question 4

The volume of blood that the heart pumps with every beat is known as the stroke volume. Stroke volume can be used to indicate fitness level. The table gives informa... show full transcript

Worked Solution & Example Answer:The volume of blood that the heart pumps with every beat is known as the stroke volume - Edexcel - GCSE Biology - Question 4 - 2012 - Paper 1

Step 1

Calculate the stroke volume of the athlete during exercise.

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Answer

To calculate the stroke volume during exercise, we use the formula for cardiac output:

$\text{Cardiac Output} = \text{Stroke Volume} \times \text{Heart Rate}$

We can rearrange this to find the stroke volume:

$\text{Stroke Volume} = \frac{\text{Cardiac Output}}{\text{Heart Rate}}$

Substituting the values:

$\text{Stroke Volume} = \frac{30.4}{182} \approx 0.167 \text{ dm}^3$

Thus, the stroke volume of the athlete during exercise is approximately 0.167 dm³.

Step 2

Explain why it is important that the cardiac output of the athlete increases during exercise.

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Answer

During exercise, muscles require more oxygen and nutrients to produce energy, as they work harder and contract faster. The increase in cardiac output ensures that more blood, rich in oxygen and glucose, is delivered to the active muscles. Additionally, it facilitates the removal of carbon dioxide and other metabolic wastes. An increased cardiac output supports aerobic respiration, thus enhancing overall performance and stamina.

Step 3

Describe how the circulatory system transports substances around the body.

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Answer

The circulatory system transports substances through a network of blood vessels:

Arteries: transport oxygenated blood away from the heart to the tissues. The aorta is a major artery that carries blood from the heart.
Veins: return deoxygenated blood back to the heart. The vena cava collects blood from the body and directs it back into the heart.
Capillaries: are small blood vessels where the exchange of materials occurs. They facilitate the transfer of oxygen, nutrients, and other substances between the blood and surrounding cells.
Substances in plasma: such as hormones and nutrients, are carried in the blood to various body locations, while red blood cells transport oxygen to cells and tissues.

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The volume of blood that the heart pumps with every beat is known as the stroke volume - Edexcel - GCSE Biology - Question 4 - 2012 - Paper 1

Worked Solution & Example Answer:The volume of blood that the heart pumps with every beat is known as the stroke volume - Edexcel - GCSE Biology - Question 4 - 2012 - Paper 1

Calculate the stroke volume of the athlete during exercise.

Explain why it is important that the cardiac output of the athlete increases during exercise.

Describe how the circulatory system transports substances around the body.

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