Electrical conduction of the heart

Question 1

What is the sequence of electrical conduction of the heart?

Answer 1

Sinoatrial (SA) node → atrioventricular (AV) node → Bundle of His and its (right and left branches) → Purkinje fibers

Question 2

The SA node is a group of cardiac muscle cells that are autorhythmic. What does that mean?

Answer 2

Contracts by itself WITHOUT any neural input.

Question 3

What is the function of the SA node?

Answer 3

Causes atrial systole (contraction).

[Blood flows from the atria into the ventricles.]

Question 4

Which area of the heart’s electrical conduction is known as the “pacemaker”?

Answer 4

SA node

Question 5

Which area of the heart is responsible for the delay of conduction between the atria and ventricles?

Answer 5

AV node

“gate-keeper”

Question 6

Why does the AV node cause a delay in conduction?

Answer 6

Because it allows the ventricles to fill completely before contraction.

Question 7

What is the difference between systole and diastole?

Answer 7

• Systole: contraction
• Diastole: relaxation

Question 8

[Mnemonic]

“I Contracted a Cyst“ - Systole happens during contraction.

(how to remember what systole is)

Answer 8

“I Contracted a Cyst“ - Systole happens during contraction.

Question 9

What is the function of the parasympathetic vagus nerve in electrical conduction of the heart?

Answer 9

Slows down heart contractions and produces the resting heart rate (60-100 bpm).