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A&P Quarter 2.2 > Electrical System of the Heart > Flashcards

Electrical System of the Heart Flashcards

1
Q

How does the heart’s electrical system develop?

A

During embryonic development, some cells become autorhythmic

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2
Q

An inherent and rhythmic ______ activity is the force behind the heart’s continuous beating, but it is regulated by _________ (___).

A

Electrical

Hormones (ANS)

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3
Q

What is the “pacemaker” of the heart?

A

SA Node

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4
Q

What does SA Node stand for?

A

Sinoatrial node

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5
Q

Where is the SA node?

A

Medial to the opening of the superior vena cava

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6
Q

The SA node has an inherent rate of ___ bpm, but “____ ____” holds the HR to__-__ bpm

A

100
Vagal Tone
70-80

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7
Q

The normal heartbeat triggered by the SA node is called ______ ______.

A

Sinus rhythm

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8
Q

Signal goes from the SA node to…

A

Both Atria

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9
Q

AV node stands for?

A

Atrioventricular node

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10
Q

Where is the AV node?

A

In lower interatrial septum, above tricuspid valve

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11
Q

What does the AV act as?

A

This node acts as an electrical gateway to the ventricles

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12
Q

What happens to the electrical impulse at the AV node?

A

At AV node, impulse is delayed .1 seconds, allowing the atria to respond and complete their contraction before the ventricles contract

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13
Q

The AV bundle is also called the …

A

Bundle of His

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14
Q

Where is the bundle of His?

A

Superior part of interventricular septum

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15
Q

What is the only electrical connection between the atria and ventricles?

A

Bundle of His/AV bundle

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16
Q

The AV bundle forks into __ branches. Called…?

A

2

Right and Left Branches

17
Q

Where are the right and left branches? Where do they go?

A

Both in interventricular septum

They descend towards the apex of the heart, continuing to separate ventricles

18
Q

What are Purkinje fibers?

A

Nerve like processes that arise from the lower bundle branches and turn upwards to spread throughout the ventricular myocardium

19
Q

Purkinje fibers are _______ ______ cells to conduct signal rapidly. The network is more elaborate in the ____ ventricle.

A

large diameter

Left

20
Q

The electrical signal comes first to the papillary muscles, then the ventricle from _____ _____.

A

Purkinji fibers

21
Q

In the heart, signals pass from cell to cell via…

A

Gap junctions and intercalated discs

22
Q

What is an EKG?

A

Electrocardiogram- Detects the conduction of action potentials through the myocardium during the cardiac cycle

23
Q

What does an EKG do? How does it work?

A

This gives a wealth of information about heart function

The cardiac cycle produces electrical currents that can be measured at the surface of the body

24
Q

What is the P wave?

A

Atrial depolarization-Onset of atrial contraction

25
Q

During the P wave, where is electrical current I the heart?

A

Spreads from SA node through atria

26
Q

What is the QRS complex?

A 
Ventricular depolarization (atrial repolarization hidden here)
Onset of ventricular contraction
27
Q

Why does the QRS complex have a complex waveform?

A

Due to different sizes of the two ventricles and different lengths for them to depolarize

28
Q

What is the T wave?

A

Ventricular repolarization

29
Q

Repolarization is slower than _____________.

A

Depolarization

30
Q

Describe the T wave in regards to the QRS complex.

A

The T wave is more spread out and lower in amplitude than the QRS complex

31
Q

What is the P-Q interval? How long does it take?

A

Atria contract and begin to relax

This is the time it takes for the signal (impulse) to travel from SA to AV nodes ~.16 sec

32
Q

What is the Q-T interval? How long does it take?

A

Ventricles contract and begin to relax, 0.38 seconds

33
Q

What is the S-T segment?

A

Ventricles ejecting blood

34
Q

What is the cardiac cycle? What EKG letters describe the cardiac cycle?

A

Repetitive pumping process, all events PQRST

1 complete contraction and relaxation of all 4 heart chambers

35
Q

How long is the cardiac cycle?

A

About .8 seconds in a normal adult; .25-.3 seconds in a newborn
Can be 1.0 seconds or more in an athlete

A&P Quarter 2.2 (22 decks)

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