Control of heart rateAQA A-Level Biology: Flashcards
What these 14 flashcards ask
- What does myogenic mean?
- What initiates the heartbeat?
- What happens when the wave of excitation leaves the SAN?
- Why is there non-conducting tissue between the atria and the ventricles?
- What is the role of the AVN?
- What is the role of the bundle of His and Purkyne tissue?
- Why do the ventricles contract from the apex upwards?
- Where are chemoreceptors found and what do they detect?
- Where are pressure receptors found?
- Where is the cardiac centre?
- Which nerves increase heart rate?
- Which nerves decrease heart rate?
- What is the effector in the control of heart rate?
- How does the heart respond to a rise in blood pressure?
Exam questions on Control of heart rate
- A mammalian heart is removed from the body and placed in warm, oxygenated saline solution. All the nerves to it have been cut. The heart continues to beat rhythmically for several minutes.Explain why the wave of excitation is carried by Purkyne tissue down the septum to the apex of the heart before it spreads upwards through the ventricle walls.2 marks
- A volunteer holds her breath for 30 seconds. During this time the carbon dioxide concentration of her blood rises and her heart rate increases from 70 to 85 beats per minute.Explain how the rise in carbon dioxide concentration leads to the increase in her heart rate.2 marks
- Physiologists investigate how the autonomic nervous system controls the heart rate of an anaesthetised mammal at rest. With all nerves intact, the resting heart rate is 90 beats per minute. When the parasympathetic nerve to the sinoatrial node (SAN) was cut, the rate rose to 110 beats per minute. When the sympathetic nerve to the SAN was cut instead, the rate fell to 80 beats per minute. When both nerves were cut, the heart continued to beat at 100 beats per minute.The blood pressure of this mammal suddenly rises. Describe how pressure receptors lead to a return of the heart rate towards normal.3 marks
Written by the Exaim team, led by Shaun Daswani (Head of Upper Secondary, Improve ME Institute; MSc Financial Mathematics, Imperial College London; BSc, UCL) and Jason Daswani (operational lead, Improve ME Institute; LSE).