Control Of Heart Rate Flashcards
What does the autonomic nervous system control?
The involuntary activities of internal muscles and glands
Define autonomic
Self-governing
What is the autonomic nervous system divided into?
The sympathetic and parasympathetic nervous system
What is the sympathetic nervous system?
The sympathetic nervous system stimulates effectors to help us cope with stressful situations by heightening our senses
What is the parasympathetic nervous system?
The parasympathetic nervous system inhibits effectors and controls activities under normal resting conditions
What can the actions of the sympathetic and parasympathetic nervous system be described as?
Antagonistic
What region of the brain controls changes in the heart rate?
Medulla oblongata
What are the 2 centres of the medulla oblongata and what are they linked to?
A centre that increases heart rate which is linked to the SA node by the sympathetic nervous system and a centre which decreases the heart rate and is linked to the parasympathetic nervous system
What do receptors respond to?
Chemical and pressure changes in the blood
Where are chemoreceptors found?
In the wall of the carotid arteries
What are chemoreceptors sensitive to?
Changes in the pH of the blood that result from changes in the CO2 concentration
When the blood has a higher than normal concentration of carbon dioxide, what is lowered?
The pH
When the chemoreceptors in the walls of the carotid arteries and the aorta detect the increase in CO2, ho who they react?
They increase the frequency of nervous impulses to the centre in the medulla oblongata that increases heart rate
How does an increased blood flow return the blood pH to normal?
More carbon dioxide is removed by the lungs so the CO2 level of the blood returns to normal
What happens once the blood pH is returned to normal?
The chemoreceptors send fewer nerve impulses to the medulla oblongata and therefore fewer nerve impulses are sent to the SA node which decreases the heart rate to normal
