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8 Cards in this Set
- Front
- Back
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What is cardiac muscle described as and why? |
Myogenic because it relaxes and contracts without receiving impulses from neurones |
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How does the heart contract? |
•the sinoatrial node (SAN) located in the wall of the right atrium sends a wave of electrical impulse at regular intervals to the atrioventricular node. •the bands of non conducting collagen tissue prevents the electrical impulses travelling to the ventricles so only the atria contracts •the AVN sends waves of electrical impulses to the bundle of his which is in between the ventricles and extend into fine muscle fibres called the purkyne tissue •slight delay before avn reacts to make sure atria has been fully emptied •purkyne tissue carried electrical waves into muscular walls of ventricles so they could trace from bottom up |
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What part of the brain controls the rate at which the san fires? |
Medulla oblongata |
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Where are the baroreceptors and chemoreceptors? |
Baroreceptors- aorta, carotid arteries Chemoreceptors-Aorta, carotid arteries and medulla |
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How is high blood pressure controlled? |
•baroreceptors detect the high blood pressure •send impulses to medulla along sensory neurone •medulla process information and sends information along parasympathetic neurone. •these secrete acetyl choline which binds to receptors on the SAN •this lowers heart rate and lowers blood pressure |
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How is low blood pressure controlled? |
•baroreceptors detect low blood pressure •sends impulses to medulla along sensory neurone •medulla processes information and sends impulses along sympathetic neurone •these secrete noradrenaline which binds to receptors on SAN and this increases heart rate which increases blood pressure |
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How is high o2, low co2 and high ph controlled? |
•chemoreceptors detect the chemical change in blood •send impulses along sensory neurone to medulla •medulla processes information and sends impulses along parasympathetic neurone which secrets acetylcholine and binds to receptors on SAN •this reduces heart rate |
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How is low 02, high co2 and low ph controlled? |
•chemoreceptors detect chemical changes in blood •impulses are sent along the medulla along sensory neurone •medulla processes information and sends impulses along sympathetic neurone which secretes noradrenaline and increases heart rate |
