Result of all the chemical reactions taking place in the cytoplasm.
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How does the heart adapt to supply more oxygen and glucose? (3)
Increased heart rate, heart can increase the strength of its contractions, increase the volume of blood pumped per beat (stroke).
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What can the heart muscle be described as?
Myogenic
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What does the heart contain?
A pacemaker - sinoatrial node (SAN).
4 of 21
Describe the movement of the wave of excitation to the apex
SAN initiates wave of excitation at regular intervals. Travels over atria walls, through the atrioventricular node (AVN) and down Purkyne fibres to ventricles.
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Where does the heart get its supply of nerves from?
From the medulla oblongata of the brain.
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Where do the nerves connect and what do they affect?
Nerves connect to the SAN and affect the frequency of contractions.
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How are the nerves involved in altering the heart rate?
Action potentials sent down accelerator nerve increase heart rate. Action potentials sent down vagus nerve reduce heart rate.
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What does the heart muscle respond to?
Responds to the presence of the hormone adrenaline in the blood.
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What can the frequency of the excitation waves be controlled by?
The cardiovascular centre in the medulla oblongata.
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What is movement of the limbs detected by and what do they do?
Detected by stretch receptors in muscles. Send impulses to cardiovascular centre informing it extra oxygen may be needed which increases heart rate.
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What happens to the CO2 produced when we exercise?
Reacts with water in the blood plasma and reduced its pH.
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How is the change in pH detected?
Detected by chemoreceptors in carotid arteries, aorta and brain.
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What is the role of the chemoreceptors?
Send impulses to the cardiovascular centre, which increases the heart rate.
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How does a reduction in CO2 cause the heart rate to decrease?
Less CO2 reduces the activity of the accelerator pathway.
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What effect does the presence of adrenaline have?
Increases the heart rate to help to prepare the body for activity.
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How is blood pressure monitored?
By stretch receptors in the walls of the carotid sinus.
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What is the carotid sinus?
A small swelling in the carotid artery. If blood pressure rises too high, stretch receptors send signals to cardiovascular centre. Heart rate reduced.
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What is a pacemaker?
A device that delivers an electrical impulse to the heart muscle.
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Describe modern pace makers
Only about 4cm long. May be implanted under the skin and fat on the chest and are capable of responding to the activity of the patient.
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Where can some pacemakers deliver impulses to?
Deliver impulses to the ventricle walls.
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Other cards in this set
Card 2
Front
How does the heart adapt to supply more oxygen and glucose? (3)
Back
Increased heart rate, heart can increase the strength of its contractions, increase the volume of blood pumped per beat (stroke).
Card 3
Front
What can the heart muscle be described as?
Back
Card 4
Front
What does the heart contain?
Back
Card 5
Front
Describe the movement of the wave of excitation to the apex
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