How does the cardiovascular system deliver oxygen during exercise, and what do heart rate, stroke volume and cardiac output mean?
The structure of the heart and the pathway of blood, the double circulatory system, the three types of blood vessel, and heart rate, stroke volume and cardiac output applied to physical activity.
A focused CCEA GCSE Physical Education answer on the cardiovascular system, covering the heart and the pathway of blood, the double circulatory system, arteries, veins and capillaries, and heart rate, stroke volume and cardiac output in sport.
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What this dot point is asking
CCEA wants you to describe the heart and the pathway of blood, explain the double circulatory system, know the three blood vessels, and define and use heart rate, stroke volume and cardiac output, applied to exercise. The cardiac output equation and the pathway of blood are common CCEA questions, so learn both precisely.
The heart and the pathway of blood
The pathway of blood is a favourite CCEA question. Learn the order:
- Vena cava brings deoxygenated blood from the body into the right atrium.
- Blood passes into the right ventricle, which pumps it through the pulmonary artery to the lungs.
- Oxygenated blood returns through the pulmonary vein into the left atrium.
- Blood passes into the left ventricle, which pumps it through the aorta to the whole body.
The double circulatory system
The left ventricle has a thicker, more muscular wall than the right because it pumps blood all around the body at high pressure, whereas the right ventricle only pumps to the nearby lungs.
The blood vessels
| Vessel | Direction | Pressure | Key feature |
|---|---|---|---|
| Artery | Away from the heart | High | Thick, muscular, elastic walls |
| Vein | Back to the heart | Low | Thin walls, wide lumen, valves |
| Capillary | Between them | Falling | Walls one cell thick for exchange |
Arteries carry blood away from the heart, veins carry it back, and capillaries are where oxygen, glucose and carbon dioxide are exchanged with the muscles.
Heart rate, stroke volume and cardiac output
Examples in context
Example 1. Why a trained heart beats slowly at rest. Endurance training makes the heart muscle stronger, so it pumps more blood per beat (a larger stroke volume). To deliver the same resting cardiac output the heart can beat fewer times per minute, so a trained athlete often has a low resting heart rate, sometimes below 50 bpm. This is called bradycardia and is a sign of a fit cardiovascular system. CCEA links this to the long-term effects of exercise.
Example 2. Delivering oxygen in a sprint. As a sprinter explodes off the blocks, the muscles demand oxygen rapidly. Heart rate and stroke volume rise sharply, so cardiac output increases, pushing more oxygenated blood to the legs. At the same time the capillaries in the muscles allow fast exchange of oxygen into the cells and carbon dioxide out. This shows the cardiovascular and respiratory systems working together to meet the demand of exercise.
Try this
Q1. Write the equation that links cardiac output, stroke volume and heart rate. [1 mark]
- Cue. Cardiac output = stroke volume × heart rate.
Q2. Name the blood vessel that carries blood away from the heart to the body. [1 mark]
- Cue. The aorta (an artery).
Exam-style practice questions
Practice questions written in the style of CCEA exam questions on this dot point, with worked answer explainers. The year tag is the paper they imitate, not the source.
CCEA 2023 Paper 14 marksDefine cardiac output and explain how it increases during exercise.Show worked answer →
Two marks for the definition and equation, two for how it rises in exercise.
Cardiac output is the volume of blood ejected from the heart in one minute.
Cardiac output equals stroke volume (the volume of blood ejected from the heart in one beat) multiplied by heart rate (the number of beats per minute).
During exercise the heart beats faster (heart rate rises) and beats more strongly (stroke volume rises), so cardiac output increases.
This delivers more oxygenated blood to the working muscles, supplying the oxygen needed for aerobic respiration and removing carbon dioxide.
Markers reward cardiac output defined as blood per minute, the equation stroke volume times heart rate, and both factors rising to deliver more oxygen.
CCEA 2020 Paper 14 marksDescribe the pathway of blood through the heart, starting as deoxygenated blood returns from the body.Show worked answer →
Four marks for the correct order of the pathway.
Deoxygenated blood returns from the body in the vena cava and enters the right atrium.
It passes into the right ventricle, which pumps it through the pulmonary artery to the lungs to pick up oxygen.
Oxygenated blood returns from the lungs in the pulmonary vein to the left atrium.
It passes into the left ventricle, which pumps it through the aorta to the rest of the body.
Markers reward the order: vena cava, right atrium, right ventricle, pulmonary artery, lungs, pulmonary vein, left atrium, left ventricle, aorta.
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