Control of heart rate Flashcards
1
Q
Where does sensory information come from?
A
- the sensory information reaching our central nervous system comes from receptors within our bodies responding to external and internal stimuli
2
Q
What is the autonomic nervous system?
A
- the autonomic nervous system controls the involuntary subconscious activities of internal muscles and glands like those involved in the fight or flight response
- it is divided into the sympathetic nervous system which is exciter and increases activity during exercise and the parasympathetic nervous system which inhibits activity to conserve energy
- these two systems are antagonistic so work as opposites
3
Q
How is heart rate controlled?
A
- a nerve impulse is generated that will either cause a parasympathetic or sympathetic response in the cardiac muscle from the medulla
- in the cardiac muscle a wave of electrical excitation spreads from the SAN across the atria, making them contract
- the atrioventricular septum prevents the wave reaching the ventricles
- a second wave of excitation is released from the Purkyne tissue, causing the ventricles to contract
4
Q
How do chemoreceptors control heart rate?
A
- when there is lots of CO2 in the blood the pH is lowered as it turns into an acid this is detected by chemoreceptors in the carotid arteries
- this generates more nerve impulses to the medulla which increases the activity of the SAN via the sympathetic nervous system which increases the heart rate
- this increases blood flow which means more CO2 is removed at the lungs so pH returns to normal signalling the medulla to return the heart rate to normal
5
Q
How do pressure receptors control heart rate?
A
- pressure receptors in the carotid arteries and the aorta detect blood pressure
- if the blood pressure is higher than normal more nerve impulses are sent to the medulla which decreases the activity of the SAN via the parasympathetic nervous system leading to a decrease in heart rate
