Cardiovascular system — AQA A-Level Physical Education
Test yourself on Cardiovascular system with AQA A-Level practice questions.
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Your focus
- Understanding of the impact of physical activity and sport on the health and fitness of the individual.
Cardiovascular system exam tips
Quick Revision Summary (Key Takeaway)
The cardiovascular system is a closed double-circulatory network comprising the heart, blood vessels and blood, responsible for transporting oxygen, nutrients, hormones and waste products around the body. For AQA A-Level Physical Education, students must understand cardiac structure and conduction, the cardiac cycle, vascular shunting, venous return mechanisms, and the acute and chronic responses of the heart and blood vessels to physical activity.
Topic Overview
The cardiovascular system is a central topic in AQA A-Level Physical Education, covering the structure and function of the heart, blood vessels and blood. It explains how oxygen and nutrients are transported to working muscles and how waste products such as carbon dioxide are removed. Understanding the cardiac cycle, conduction system and vascular shunting is essential for analysing how the body meets the demands of physical activity.
This topic links closely with the respiratory and energy systems, and it underpins later work on training adaptations, VO2 max and sports performance. Students must be able to describe acute responses to exercise, such as increased heart rate and redistribution of blood flow, and chronic adaptations following training, such as bradycardia and increased stroke volume. Exam questions often require application to specific sports and evaluation of how these changes affect performance.
Key Concepts
- →The heart has four chambers: right atrium and ventricle receive deoxygenated blood from the body and pump it to the lungs; left atrium and ventricle receive oxygenated blood from the lungs and pump it to the body via the aorta.
- →The conduction system: the sinoatrial node (SAN) initiates impulses, the atrioventricular node (AVN) delays the impulse to allow ventricular filling, and the bundle of His and Purkinje fibres spread the impulse through the ventricles.
- →The cardiac cycle consists of atrial systole, ventricular systole and diastole, with pressure changes causing valves to open and close, producing heart sounds.
- →Vascular shunting redistributes blood during exercise: vasodilation of arterioles in working muscles and vasoconstriction in non-essential areas, controlled by the vasomotor centre.
- →Venous return is aided by the skeletal muscle pump, respiratory pump, pocket valves and smooth muscle in veins, ensuring blood returns to the right atrium.
Examiner Tips
- 💡Always use specific anatomical terminology (e.g. 'sinoatrial node', 'atrioventricular node', 'bundle of His', 'Purkinje fibres') rather than vague terms like 'pacemaker' or 'nerves'.
- 💡When explaining responses or adaptations, link the change to its effect on performance (e.g. 'increased stroke volume leads to greater oxygen delivery, delaying fatigue').
- 💡For calculation questions, show your working clearly and include units (L/min or mL/min) to secure full marks.
Common Mistakes
- Students often think the left side of the heart pumps deoxygenated blood to the lungs. Correction: the right side pumps deoxygenated blood to the lungs via the pulmonary artery; the left side pumps oxygenated blood to the body via the aorta.
- Many believe that heart rate increases solely because of adrenaline. Correction: heart rate is regulated by the cardiac accelerator and inhibitory centres in the medulla oblongata, which respond to chemoreceptors, baroreceptors and proprioceptors, using sympathetic and parasympathetic nerves.
- Students frequently state that blood pressure decreases during exercise. Correction: systolic blood pressure increases due to greater cardiac output, while diastolic pressure remains relatively stable or may decrease slightly due to vasodilation in working muscles.
Revision Plan
- 1Week 1, Days 1-2: Revise the structure of the heart and conduction system using diagrams and labelling exercises. Create flashcards for key terms.
- 2Week 1, Days 3-4: Learn the cardiac cycle and vascular shunting. Practice explaining these in writing using correct terminology and pressure changes.
- 3Week 1, Days 5-7: Study acute responses to exercise (heart rate, stroke volume, cardiac output, blood pressure, redistribution of blood flow) and complete past-paper questions.
- 4Week 2, Days 1-3: Learn chronic adaptations to aerobic and anaerobic training. Compare adaptations and link to performance in different sports.
- 5Week 2, Days 4-7: Complete a full topic test under timed conditions, mark using the mark scheme, and review examiner reports for common pitfalls.
Exam Question Types
- 📋Multiple-choice and short-answer questions (1-2 marks) testing definitions, e.g. 'Define cardiac output' or 'State the role of the AVN'.
- 📋Data analysis questions (3-4 marks) requiring interpretation of heart rate, stroke volume or blood pressure graphs, often asking students to calculate cardiac output or describe trends.
- 📋Extended writing questions (6-9 marks) asking students to explain or evaluate cardiovascular responses and adaptations to exercise, often applied to a specific sport or training programme.
- 📋Synoptic questions linking the cardiovascular system to the respiratory or energy systems, requiring integrated knowledge across topics.
Command Word Expectations (AQA)
Describe
Give a detailed account of the main features or steps. For example, 'Describe the cardiac cycle' requires a sequential account of atrial systole, ventricular systole and diastole with reference to pressure and valves. No explanation of why is required, but accurate terminology is essential.
Explain
Give reasons or mechanisms for a response or adaptation. For example, 'Explain how stroke volume increases during exercise' requires reference to increased venous return, the Frank-Starling mechanism, and increased sympathetic stimulation. Each point must be linked to a cause and effect.
Evaluate
Make a judgement based on evidence, weighing up strengths and weaknesses or advantages and disadvantages. For example, 'Evaluate the importance of cardiovascular adaptations for a marathon runner' requires discussion of increased stroke volume, capillarisation and blood volume, and a conclusion on their relative importance for endurance performance.
How Students Lose Marks (Examiner Pitfalls)
Pitfall: Students confuse the roles of the sympathetic and parasympathetic nervous systems during exercise, often stating that the parasympathetic nervous system increases heart rate.
❌ Weak Answer (Loses Marks):During exercise the parasympathetic nervous system increases heart rate so more oxygen gets to the muscles.
Example improved answer:During exercise, chemoreceptors and proprioceptors detect increased carbon dioxide, decreased pH and muscle movement. This stimulates the cardiac accelerator centre in the medulla oblongata, which increases sympathetic nervous system activity via the cardiac accelerator nerve. Noradrenaline is released at the sinoatrial node (SAN), increasing the frequency of electrical impulses and therefore heart rate. At the same time, parasympathetic activity via the vagus nerve decreases, further raising heart rate.
Examiner Tip: Always link the nervous system to the specific node or structure it acts on (SAN, AVN, cardiac muscle) and name the neurotransmitter (noradrenaline for sympathetic, acetylcholine for parasympathetic).
Pitfall: Students describe the cardiac cycle in the wrong order or omit the role of valves and pressure changes, losing marks in 4-6 mark questions.
❌ Weak Answer (Loses Marks):The heart beats and blood goes from the atria to the ventricles and then out. The valves open and close.
Example improved answer:The cardiac cycle has three phases. During atrial systole, the atria contract, increasing pressure and pushing blood through the atrioventricular (AV) valves into the ventricles. During ventricular systole, the ventricles contract, increasing pressure above that in the atria and arteries, forcing the AV valves shut (first heart sound) and opening the semilunar valves so blood enters the aorta and pulmonary artery. During diastole, the atria and ventricles relax, pressure falls, the semilunar valves close (second heart sound) and the AV valves open as blood flows passively from the atria to the ventricles.
Examiner Tip: Use the terms 'atrial systole', 'ventricular systole' and 'diastole' in the correct sequence and always refer to pressure changes and valve opening/closing as cause and effect.
Step-by-Step Worked Solutions
Question: A 70 kg athlete has a resting heart rate of 60 bpm and a resting stroke volume of 70 mL. During maximal exercise, their heart rate rises to 190 bpm and stroke volume to 120 mL. Calculate the cardiac output at rest and during maximal exercise, and explain the significance of the increase.
- 1.Step 1: Identify given facts: Resting HR = 60 bpm, resting SV = 70 mL; maximal HR = 190 bpm, maximal SV = 120 mL.
- 2.Step 2: Apply the formula: Cardiac output (Q) = Heart rate (HR) x Stroke volume (SV).
- 3.Step 3: Calculate resting Q: 60 bpm x 70 mL = 4200 mL/min = 4.2 L/min.
- 4.Step 4: Calculate maximal Q: 190 bpm x 120 mL = 22800 mL/min = 22.8 L/min.
- 5.Step 5: State final conclusion with units: Resting cardiac output is 4.2 L/min and maximal cardiac output is 22.8 L/min, an increase of 18.6 L/min. This increase ensures greater oxygen delivery to working muscles and faster removal of carbon dioxide and lactate.
Final Answer: Resting Q = 4.2 L/min; maximal Q = 22.8 L/min. The increase supports increased aerobic respiration and delays fatigue during exercise.
Question: Explain how the cardiovascular system responds to a 10-week aerobic training programme and how these adaptations improve performance in a 1500 m race. (6 marks)
- 1.Step 1: Identify the training type: aerobic training leads to cardiac hypertrophy, particularly of the left ventricle.
- 2.Step 2: Describe structural adaptations: increased left ventricular volume and thickness, increased stroke volume at rest and during exercise, and increased capillarisation around skeletal muscle.
- 3.Step 3: Describe functional adaptations: reduced resting heart rate (bradycardia), increased cardiac output during maximal exercise, increased arteriovenous oxygen difference (a-vO2 diff), and increased blood plasma volume.
- 4.Step 4: Link to performance: greater stroke volume means more oxygenated blood delivered per beat, allowing the athlete to maintain a higher aerobic power output for longer, delaying the onset of anaerobic respiration and lactate accumulation.
- 5.Step 5: Conclude: These adaptations improve endurance capacity, allowing the athlete to run at a faster pace for the duration of the 1500 m race.
Final Answer: Aerobic training causes cardiac hypertrophy, increased stroke volume, capillarisation and blood volume, which together increase oxygen delivery and endurance performance in a 1500 m race.
Active Recall Memory Test
What is the equation for cardiac output and what are the typical units?
Key Fact: Cardiac output (Q) = Heart rate (HR) x Stroke volume (SV). Units are typically litres per minute (L/min) or millilitres per minute (mL/min).
Name the three phases of the cardiac cycle in order.
Key Fact: Atrial systole, ventricular systole, diastole.
What is vascular shunting and why does it occur during exercise?
Key Fact: Vascular shunting is the redistribution of blood flow. During exercise, arterioles in working muscles vasodilate to increase blood flow, while arterioles in non-essential areas (e.g. digestive system) vasoconstrict. This ensures oxygen and nutrients are delivered to active muscles and waste products are removed efficiently.
State three chronic adaptations of the cardiovascular system to aerobic training.
Key Fact: Cardiac hypertrophy (increased left ventricular volume and wall thickness), increased stroke volume, increased capillarisation, increased blood plasma volume, reduced resting heart rate (bradycardia).
Frequently Asked Questions
What is the difference between the sympathetic and parasympathetic nervous systems in controlling heart rate?
The sympathetic nervous system increases heart rate by releasing noradrenaline at the sinoatrial node (SAN), speeding up the rate of electrical impulses. The parasympathetic nervous system decreases heart rate by releasing acetylcholine at the SAN via the vagus nerve, slowing impulse generation. During exercise, sympathetic activity increases while parasympathetic activity decreases, leading to a higher heart rate.
How does the cardiovascular system respond to exercise?
During exercise, heart rate, stroke volume and cardiac output increase to deliver more oxygen to working muscles. Blood pressure rises, particularly systolic pressure, and vascular shunting redistributes blood flow away from non-essential organs to active muscles. Venous return is aided by the skeletal muscle pump and respiratory pump, and the arteriovenous oxygen difference (a-vO2 diff) increases as muscles extract more oxygen.
What are the long-term effects of aerobic training on the heart?
Long-term aerobic training leads to cardiac hypertrophy, especially of the left ventricle, increasing stroke volume and cardiac output during maximal exercise. Resting heart rate decreases (bradycardia) due to increased parasympathetic tone and greater stroke volume. Capillarisation increases around muscles, improving oxygen delivery, and blood plasma volume increases, reducing blood viscosity and improving thermoregulation.
Why does stroke volume increase during exercise?
Stroke volume increases due to the Frank-Starling mechanism: increased venous return stretches the ventricular walls, causing a more forceful contraction. Additionally, increased sympathetic stimulation increases the contractility of the heart muscle. Stroke volume plateaus at around 40-60% of maximal exercise intensity, after which further increases in cardiac output are mainly due to heart rate.
What is the role of the AVN in the cardiac cycle?
The atrioventricular node (AVN) receives the electrical impulse from the sinoatrial node (SAN) and delays it by approximately 0.1 seconds. This delay allows the atria to complete their contraction and the ventricles to fill with blood before ventricular systole begins. The impulse then travels down the bundle of His and Purkinje fibres to stimulate ventricular contraction.
How do you calculate cardiac output and what is a typical value at rest?
Cardiac output (Q) is calculated as heart rate (HR) multiplied by stroke volume (SV). At rest, a typical adult has a heart rate of about 70 bpm and a stroke volume of about 70 mL, giving a cardiac output of approximately 5 L/min. During maximal exercise, cardiac output can increase to 20-25 L/min in trained athletes.