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25 Cards in this Set
- Front
- Back
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Sympathetic ANS
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Increases heart rate
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Parasympathetic ANS
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Decreases heart rate
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The parasympathetic nerve which innervates the heart is the...
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Vagus nerve
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The neurotransmitter released by the parasympathetic ANS is...
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acetylcholine
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The neurotransmitter released by the sympathetic ANS is...
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noradrenaline
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What are chronotropic effects?
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Influences on HR
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Noradrenaline, adrenaline, glucagon, thyroid all...
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Have positive chronotropic effects
Increase HR Depolarization (less negative) of ion channels so action potentials can be more easily generated |
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Acetylcholine has a negative chronotropic effect how?
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Hyper-polarization of cell membranes so they are more negative and action potentials are harder to generate
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Tachycardia
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fast HR
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Low HR
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Bradychardia
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Stroke Volume =
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EDV x ESV
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What three aspects influence stoke volume?
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Preload
Energy of Contraction Afterload |
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What is 'starlings law of the heart'?
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'Energy contraction of the heart is proportional to the initial length of the cardiac muscle fibre'
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What are key factors influencing venous return?
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Posture
Muscle contraction Respiratory pump |
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If preload increases stroke volume
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Increase
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Greater force of contraction causes __ _________ stroke volume
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an increase
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What causes an increase in the force of contraction?
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Calcium-induced-calcium-released mechanism
Ca2+ enters the cell, promotes release of Ca2+ from store, increasing contraction |
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An increase in afterload influences stroke volume by
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Decreasing stoke volume
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Where are peripheral chemoreceptors found?
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Carotid body
Aortic arch |
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What do peripheral chemoreceptors stimulate?
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Rise in CO2, fall in pH
Stimulate cardioacceleratory and vasomotor Inhibit cardioinhibitory Promote increase in HR |
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Receptors found in carotid sinus, wall of right atrium and aortic arch
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Baroreceptors
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Which receptors are stretch receptors?
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Baroreceptors
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Baroreceptors are more sensitive to...
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Pulsative change
(Change in BP) |
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An increase in BP detected in baroreceptors leads to...
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Impulses sent to vasomotor centre
Cardiacacceleratory centre Vasodilation Decrease in HR - cardiac output |
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Where are central chemoreceptors found?
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Medulla oblongata
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