The structure and functions of the cardiovascular system, the blood vessels, cardiac output, vascular shunting, and the components and roles of blood.

A focused answer to Edexcel GCSE PE on the cardiovascular system: the structure and functions of the heart, the three blood vessels, cardiac output, vascular shunting during exercise, and the roles of red and white blood cells, platelets and plasma.

Generated by Claude Opus 4.89 min answerUpdated 2026-06-02

Reviewed by: AI editorial process; not yet individually human-reviewed

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What this dot point is asking
Structure and functions of the heart
Cardiac output
Blood vessels and vascular shunting
The components of blood

What this dot point is asking

Edexcel wants you to describe the structure and functions of the heart, the pathway of blood, the three blood vessels, how cardiac output is calculated, how vascular shunting redirects blood during exercise, and the roles of the components of blood.

Structure and functions of the heart

The functions of the cardiovascular system are to transport oxygen, carbon dioxide and nutrients, to clot open wounds, and to help regulate body temperature. The heart has four chambers: the right and left atria (top) and the right and left ventricles (bottom), separated by the septum. The right side handles deoxygenated blood and the left side handles oxygenated blood; the valves (tricuspid, bicuspid and semi-lunar) stop blood flowing backwards.

Cardiac output

For example, a heart rate of $70$ beats per minute and a stroke volume of $70$ ml gives a cardiac output of $70 \times 70 = 4900$ ml per minute. During exercise both heart rate and stroke volume rise, so cardiac output increases to deliver more oxygen to the muscles. A trained endurance athlete has a larger, stronger heart, so each beat ejects more blood (a higher stroke volume). That lets them reach a high cardiac output at a lower heart rate, and it explains their low resting heart rate (bradycardia): at rest the same blood need is met with fewer, more powerful beats.

Calculating cardiac output and reading the change with exercise

Write the equation

Start every cardiac output question with $Q = HR \times SV$ so the marker can see the method.

Substitute the resting values

For a performer at rest with $HR = 65$ beats per minute and $SV = 75$ ml, the resting cardiac output is $Q = 65 \times 75 = 4875$ ml per minute.

Substitute the exercise values

During hard exercise the same performer reaches $HR = 180$ beats per minute and $SV = 110$ ml, so $Q = 180 \times 110 = 19800$ ml per minute (about $19.8$ litres per minute).

Interpret the result

Cardiac output has risen roughly fourfold. State the consequence: far more oxygenated blood reaches the working muscles each minute, supporting aerobic energy release and clearing carbon dioxide. Always keep the unit (ml per minute) attached.

Blood vessels and vascular shunting

Arteries: carry blood away from the heart at high pressure, with thick muscular walls.
Capillaries: tiny, thin-walled vessels where gas exchange (oxygen and carbon dioxide) takes place between blood and tissue.
Veins: carry blood back to the heart at low pressure, with valves to prevent backflow.

The components of blood

Red blood cells matter most for performance, because more of them means more oxygen delivered per minute, which is one reason altitude training (and illegally, blood doping) increases endurance. If a question gives any two of cardiac output, heart rate and stroke volume, you can find the third by rearranging $Q = HR \times SV$ ; for example a cardiac output of $20000$ ml per minute at a heart rate of $200$ beats per minute gives a stroke volume of $SV = Q \div HR = 20000 \div 200 = 100$ ml.

Common traps

Saying veins always carry deoxygenated blood and arteries oxygenated blood: This is usually true, but the pulmonary artery carries deoxygenated blood and the pulmonary vein carries oxygenated blood. Define vessels by direction of flow (arteries away from the heart, veins towards it), not oxygen content.
Forgetting the unit in cardiac output: State stroke volume in ml, heart rate in beats per minute, and give cardiac output per minute. A bare number loses the unit mark.
Confusing vasodilation and vasoconstriction: Vasodilation widens vessels to increase flow to working muscles; vasoconstriction narrows them to reduce flow to inactive areas. Both happen at once during shunting.
Naming the wrong valve: The tricuspid valve is on the right, the bicuspid (mitral) valve on the left, and the semi-lunar valves guard the exits to the pulmonary artery and aorta.

Exam-style practice questions

Practice questions written in the style of Pearson Edexcel exam questions on this dot point, with worked answer explainers. The year tag is the paper they imitate, not the source.

Edexcel 20193 marksA performer has a heart rate of 60 beats per minute and a stroke volume of 75 ml at rest. Calculate their cardiac output and state the unit.

Show worked answer →

A Component 1 calculation (use of data). One mark for the equation, one for the value, one for the unit.

Use $Q = HR \times SV$ , so $Q = 60 \times 75 = 4500$ . The unit is millilitres per minute, so the answer is $4500$ ml per minute (or $4.5$ litres per minute).

A common dropped mark is leaving off the unit, or forgetting the result is per minute because heart rate is measured per minute.

Edexcel 20214 marksFigure 1 is a graph of a performer's heart rate before, during and after a training session, rising from 70 to 180 then falling to 90 beats per minute in the first three minutes of recovery. Explain how vascular shunting and the change in cardiac output meet the demands of the working muscles, using values from the graph.

Show worked answer →

A Component 1 graph-interpretation (use of data) application question that rewards reading the figure and linking it to mechanism.

Award marks for: during exercise heart rate rises (70 to 180 from the graph) and stroke volume rises, so cardiac output increases ( $Q = HR \times SV$ ), delivering more oxygenated blood per minute. Vascular shunting redistributes that blood, arterioles to the working muscles vasodilate while those to the gut and skin vasoconstrict. The fall from 180 to 90 in three minutes shows fast recovery as demand drops.

Top answers quote figures from the graph rather than describing the trend in words alone.

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Sources & how we know this

Pearson Edexcel GCSE (9-1) Physical Education (1PE0) specification — Pearson Edexcel (2016)