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Exercise causes an increase in heart rate - AQA - A-Level Biology - Question 1 - 2017 - Paper 2
Question 1
Exercise causes an increase in heart rate. Describe the role of receptors and of the nervous system in this process.
Worked Solution & Example Answer:Exercise causes an increase in heart rate - AQA - A-Level Biology - Question 1 - 2017 - Paper 2
Step 1
Chemoreceptors detect rise in CO₂/H⁺/acidity
Answer
Chemoreceptors in the body are sensitive to changes in carbon dioxide (CO₂), hydrogen ions (H⁺), and acidity. When exercise occurs, the levels of CO₂ increase in the blood. This is sensed by chemoreceptors that detect this rise in acidity.
Step 2
Baroreceptors detect changes in blood pressure
Answer
Baroreceptors are another set of receptors that monitor blood pressure. During exercise, physical activity requires changes in cardiovascular function, leading to alterations in blood pressure. Baroreceptors detect these changes and report them to the nervous system.
Step 3
Step 4
More impulses to SAN and sympathetic pathways
Answer
From the cardiac center, more impulses are relayed to the sinoatrial node (SAN) to increase heart rate. Additionally, sympathetic pathways are activated, promoting an increase in heart rate and enhancing the overall cardiac output needed for exercise.