Exercise causes an increase in heart rate - AQA - A-Level Biology - Question 1 - 2017 - Paper 1
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 1
Step 1
1. Chemoreceptors detect rise in CO₂/H⁺/acidity/carbonic acid/fall in pH
96%
114 rated
Only available for registered users.
Sign up now to view full answer, or log in if you already have an account!
Answer
Chemoreceptors are specialized cells that monitor changes in the blood's chemical composition. When exercise occurs, levels of CO₂ and acidity in the blood increase due to heightened metabolic activity, triggering these receptors.
Step 2
2. Send impulses to cardiac centre/medulla
99%
104 rated
Only available for registered users.
Sign up now to view full answer, or log in if you already have an account!
Answer
The detection of these changes leads to the transmission of nerve impulses to the cardiac center located in the medulla oblongata of the brain. This center is crucial for regulating heart rate.
Step 3
3. More impulses to SAN
96%
101 rated
Only available for registered users.
Sign up now to view full answer, or log in if you already have an account!
Answer
The cardiac center then sends increased impulses to the sinoatrial node (SAN), which is the natural pacemaker of the heart. This increase in impulses directly results in a higher heart rate.
Step 4
4. By sympathetic (nervous system for chemoreceptors/CO₂) OR By parasympathetic (nervous system for baro/pressure receptors/blood pressure)
98%
120 rated
Only available for registered users.
Sign up now to view full answer, or log in if you already have an account!
Answer
The sympathetic nervous system's activation further supports heart rate elevation by facilitating faster heartbeats, while the parasympathetic system diminishes its activity. Both systems work in concert to finely tune the heart's response during physical exertion.
