LeBlanc 1 Flashcards

1
Q

Which structure in the heart is the slowest in its conduction? Why is this so important?

A

AV node

The delay allows the time for ventricular filling

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2
Q

Are purkinje fibers fast or slow in their conduction?

A

They are fast b/c of their gap jcns. They have low electrical resistance.

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3
Q

What is the purpose of atrial & ventricular myocytes?

A

They are designed for pumping.

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4
Q

What are the pacemaker cells?

A

SA node, AV node, purkinje fiber cells

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5
Q

After SA, what transmits the electrical impulse?

A

AV node, Bachmann’s bundle–interatrial/internodal tracts
Bundle of Hiss
Purkinje fibers

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6
Q

What are the contracting cells?

A

atrial & ventricular myocytes

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7
Q

What’s the deal w/ tetanus & cardiac muscle?

A

Cardiac muscle doesn’t achieve tetanus like skeletal muscle (would be dangerous) & it is b/c it has a long refractory period. Can’t get a summation of AP.

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8
Q

Where does the impulse go directly after it leaves the SA & before it goes to the AV?

A

Atrial muscle cells & the inter nodal tracts that are in the RA.

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9
Q

What does the Bachmann bundle do?

A

It transmits the impulse from the SA node in the RA to the LA. It is an intertribal tract.

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10
Q

What is the size of the AV node? How does this affect its resistance & delay?

A

AV node is small. This means high resistance. This causes the delay.

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11
Q

Aside from around the ventricles & at the apex of the heart…where do Purkinje fibers go?

A

Into papillary muscles.

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12
Q

What is the pathway of electrical activity in the heart?

A

SA node, inter nodal tracts, Bachmann’s tract to LA, AV node, Bundle of His, Left & Right Bundle Branch, Purkinje fibers.

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13
Q

What is an insulator of the AV node?

A

atrioventricular fibrous tissue.

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14
Q

What would retrograde excitation show on an ECG?

A

an inverted P wave

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15
Q

What is the Bundle of Kent?
Which disease is it present in?
What would this do to an ECG?

A

something that allows direct communication b/w atria & ventricles w/o usual AV delay.
Wolf Parkinson White Syndrome
distance b/w P & QRS would be shorter.

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16
Q

Which is fastest…internodal tracts, ventricular cells, or Purkinje fibers?

A

Purkinje fibers are the fastest.

17
Q

What happens if the artery that supplies the SA node is blocked? Does the heart stop?

A

No, the heart doesn’t stop. Other pacemakers of the heart more downstream take over. They’re just not quite as fast.

18
Q

What are the primary, secondary, & tertiary pacemakers of the heart?

A

Primary: SA node
Secondary: AV node, Bundle of His
Tertiary: Bundle branches, Purkinje network