Chapter 11: Conduction System of the Heart Flashcards

1
Q

What initiates the electrical activity of the heat?

A

specialized muscle cells

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2
Q

wave of electrical activity

A

action potential

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3
Q

Where do impulses initiate?

A

SA (sinoatrial) node

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4
Q

What is the natural pacemaker of the heart?

A

SA node

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5
Q

Where is the SA node located?

A

In the R atrium, near the opening of the superior vena cava

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6
Q

True or false: Ability of the cardiac muscle to depolarize and contract depends on the nervous system.

A

False; it is intrinsic

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7
Q

What is the path of conduction through the heart?

A

SA node -> AV node -> AV bundle (bundle of His) -> R and L branches -> Purkinje fibers -> muscle fibers contract.

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8
Q

On average, how often does atrial systole occur?

A

every .85 seconds

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9
Q

What is one heartbeat comprised of?

A

1) Atrial systole
2) Ventricular systole
3) Diastole (heart relaxes)

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10
Q

How many heartbeats comprise one cardiac cycle?

A

1 heartbeat

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11
Q

What happens is the SA node is not working properly?

A

AV node takes over (slower HR: 40-60 bpm)

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12
Q

What happens if both the SA and AV nodes stop working?

A

Bundle of His takes over (30-40 bpm)

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13
Q

What does lack of a P wave indicate?

A

Atrial fibrillation

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14
Q

What does an elevated ST segment in an EKG represent?

A

STEMI

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