control of heart rate Flashcards

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1
Q

why is the cardiac muscle myogenic?

A

can contract/relax without receiving signals from nerves but pattern controlled in regular heartbeat

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2
Q

describe how a heartbeat is initiated and coordinated

A
  1. SAN sends a wave of electrical impulses across atria causing atrial contraction
  2. non-conducting tissues prevents the immediate contraction of the ventricles.
  3. AVN delays impulse whilst blood leaves atria.
  4. AVN sends a wave of electrical impulses down bundle of His.
  5. causing ventricles to contract from the base up.
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3
Q

Name the two types of receptors in the heart

A

Baroreceptors-in aorta and carotid arteries detect changes in blood pressure
Chemoreceptors-in aorta, carotid arteries and medulla detects change in O2/CO2 conc. and pH of the blood

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4
Q

what is the coordinator of the heart?

A

medulla oblongata

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5
Q

what does an increase in the impulses to the SAN through the sympathetic and parasympathetic nervous system do to the heart rate?

A

S=increases heart rate

P=decreases heart rate

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6
Q

what does increasing the conc. of acetylcholine or noradrenaline do to the heart rate?

A

A=slower heart rate

N=faster heart rate

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7
Q

how does the heart respond to high blood pressure?

A
  • baroreceptors in aorta detect increase and send impulses to the medulla
  • increased impulses to the SAN via parasympathetic nerves
  • release of ACh decreases impulses from SAN
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8
Q

how does the heart respond to low blood pressure?

A
  • baroreceptors in aorta detect decrease and send impulses to the medulla
  • increased impulses to SAN via sympathetic nerves
  • release of noradrenaline increases impulses from SAN/heart rate
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9
Q

how does the heart respond to high blood O2/low CO2/high pH?

A
  • chemoreceptors in aorta detect change and send impulses to the medulla
  • increased impulses to SAN via parasympathetic nerves
  • release of ACh decreases impulses from SAN/heart rate slows
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10
Q

how does the heart respond to low blood O2/high CO2/low pH?

A
  • chemoreceptors in aorta detect change and send impulses to the medulla
  • increased impulses to SAN via sympathetic nerves
  • release of noradrenaline increases impulses from SAN/faster heart rate
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