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9. Sympathetic and parasympathetic nerves regulate heart rate - Scottish Highers Human Biology - Question 9 - 2017
Question 9
9. Sympathetic and parasympathetic nerves regulate heart rate. (a) Name the part of the brain that regulates the heart rate. (b) The sympathetic and parasympathe... show full transcript
Worked Solution & Example Answer:9. Sympathetic and parasympathetic nerves regulate heart rate - Scottish Highers Human Biology - Question 9 - 2017
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Explain what this statement means.
Answer
The sympathetic and parasympathetic nerves work antagonistically means that they have opposite effects on the heart. The sympathetic nervous system is responsible for speeding up the heart rate, which is crucial in situations requiring heightened alertness or physical activity. Conversely, the parasympathetic nervous system slows down the heart rate, promoting rest and relaxation.
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Explain why the heart continues to contract when both nerves are blocked.
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The heart continues to contract when both nerves are blocked because it has its own intrinsic pacemaker activity. The sinoatrial node (SAN) generates electrical impulses that trigger heartbeats independently of the nervous system, allowing the heart to maintain a basic rhythm even in the absence of external nerve signals.
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Use information from the graph to justify this statement.
Answer
From the graph, it can be observed that when the parasympathetic nerve is blocked, there is a greater increase in heart rate compared to when the sympathetic nerve is blocked. This indicates that the parasympathetic nervous system has a more significant role in maintaining a lower resting heart rate, as it exerts a more substantial influence on the heart's pace.
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