Modification of Heart rate
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What is the modification of heart rate dependant on?
Levels of activity
Where are the two cardiovascular centres located and what are their names?
- In the medulla within the brain
- The Cardioinhibitory centre
- The Cardioacceleratory centre
What is the function of the cardioinhibitory centre?
To decrease heart rate by increasing the frequency of impulses sent along the parasympathetic nerve to the sino-atrial node
What is the function of the cardioacceleratory centre?
To increase heart rate by increasing the rate of impulses sent along the sympathetic nerve to the sino-atrial node
From where do the cardiovascular centres receive impulses?
From chemoreceptors found in the aorta, the carotid arteries and the medulla
What do chemoreceptors detect?
Carbon dioxide levels in the blood plasma
Where are pressure receptors found and what do they detect?
- Within the Aorta and the carotid artery
- Change in blood pressure is detected
When might a decrease in blood pressure occur and what would this cause?
- During exercise when more blood is diverted to muscles
- Pressure receptors send impulses to the cardioacceleratoy centre causing an increase in heart rate
Describe the bodily processes that occur during exercise
- Muscles respire more
- More carbon dioxide is produced
- This increase in CO2 is detected by chemoreceptors found in the aorta
- Impulses are sent to the cardioacceleratory centre in the medulla
- The CAC responds by sending an increased frequency of impulses along the sympathetic nerve to the sino-atrial node
- The SA node increases the rate at which it produces impulses and heart rate increases
- Increased blood flow increases the rate at which CO2 is removed at the lungs
- CO2 levels return to normal
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