module 5 - 14.6 controlling heart rate Flashcards

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1
Q

which part of the autonomic nervous system is responsible for heart rate?

A

medulla oblongata

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2
Q

what is the medulla oblongata?

A
  • located in brain stem
  • connects higher levels of the brain to the spinal cord
  • cone shaped neuronal mass responsible for involuntary functions
  • contains cardiac, respiratory, vomiting and vasomotor centres so deals with autonomic functions
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3
Q

what are the 2 centres in the medulla oblongata responsible for?

A
  • one increases heart rate through SNS using accelerator nerve connected to SAN
  • one decreases heart rate through parasympathetic NS using vagus nerve connected to SAN
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4
Q

what are the 2 sets of receptors in blood vessels?

A

baraoreceptors
chemoreceptors

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5
Q

what are baroreceptors?

A
  • measure blood pressure
  • located in aorta, vena cava and carotid arteries
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6
Q

what are chemoreceptors?

A
  • detect blood CO2 concentration by measuring blood pH
    0 located in aorta, carotid arteries and mudulla oblongata
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7
Q

what do chemoreceptors do if there is too much CO2 in blood? (opposite for too little)

A

increased muscle activity → more CO2 produced by tissues from increased respiration → blood pH is lowered → SAN increased heart rate → increased blood flow moves CO2 faster → CO2 level returns to normal

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8
Q

what do baroreceptors do if blood pressure is too high?

A
  1. baroreceptors detect change in blood pressure
  2. nervous impulses sent to medulla oblongata
  3. medulla oblongata sends nervous impulses along parasympathetic neurones to SAN
  4. heart responds by decreasing heart rate
  5. blood pressure is reduced
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9
Q

how do hormones control/influence heart rate?

A

by affecting SAN directly

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9
Q

what do baroreceptors do if blood pressure is too low?

A
  1. baroreceptors detect change in blood pressure
  2. nervous impulses sent to medulla oblongata
  3. medulla oblongata sends nervous impulses along sympathetic neurones to SAN
  4. heart responds by increasing heart rate
  5. blood pressure is increased
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