Control Of Heart Rate Flashcards
Name of system
The Autonomic Nervous System
Region of the brain controls heart ratw
Cardioregulatory centre in the medulla
What is the medulla made up of
Acceleratory centre = heart rate speeds up
Inhibitory centre = heart rate slows
What are both of the centres that control heart rate connected to
Sinoatrial node by nerves
The SAN IS IN THE HEART
Describe what happens when the acceleratory centre is activated
Impulses sent along sympathetic neurones to the SAN
Noradrenaline is secreted at the synapse with the SAN
Noradrenaline causes the SAN to increase the frequency of electrical waves produced to increase the heart rate
Describe what happens when the inhibitory centre is activated
Once activated impulses are sent along the parasympathetic neurones to the SAN
Acetylcholine is secreted at the synapse with the SAN
ACh causes the SAN to reduce the frequency of electrical waves produces, reducing the heart rate to resting rate
What internal conditions change due to exercise
CO2 concentration in the blood increaes
Initial fall in blood pressure caused by the dilation of muscle arterioles
Name of the stimuli created when exercise changes internal conditions
Created an internal stimuli
What is the internal stimuli detected by
Chemoreceptors and pressure receptors located in the aorta and the carotid arteries (oxygenated blood)
What do chemoreceptors do
Release nerve impulses that are sent to the acceleratory and inhibitory centres
Describe the whole process of what occurs when heart rate is increased
1) STIMULI: Increased CO2 conc in blood, decrease in blood pressure
2) RECEPTORS: Increased stimulation of chemoreceptors and pressure receptors
3) COORDINATION: Acceleratory centre in medulla sends impulses via sympathetic nerves
4) EFFECTORS: SAN stimulated by noradrenaline
5) RESPONSE: Increased frequency of waves of electrical activity spread across atria and ventricles and heart rate increases
What is adrenaline
Hormone produced by adrenal glands similar to noradrenaline
Released during fight or flight response
Causes heart rate to increase
Why is adrenaline advantageous for blood supply
Increases heart rate = increase blood supply to respiring musckes
This means muscles will have more O2 and glucose for respiration
Allowing high-intensity activities (like running away from predators) to be an immediate response
