Heart

Question 1

Electrical current flow through the heart = ?

Answer 1

• Sinoatrial (SA) Node →
• Atrioventricular (AV) Node →
• Bundle of His →
• Bundle Branches →
• Purkinje Fibers

Question 2

Sinoatrial (SA) Node:

• Location = ?
• Function = ?
• Effect = ?

Answer 2

Sinoatrial (SA) Node:

• Location: Upper part of the right atrium.
• Function: The SA node generates an electrical impulse. It’s often called the heart’s natural pacemaker.
• Effect: This impulse causes the atria (the two upper chambers of the heart) to contract and push blood into the ventricles (the two lower chambers).

Question 3

Atrioventricular (AV) Node

• Location = ?
• Function = ?
• Effect = ?

Answer 3

Atrioventricular (AV) Node:

• Location: Between the atria and the ventricles.
• Function: The AV node receives the electrical impulse from the SA node. It delays the impulse slightly to ensure the atria have finished contracting before the ventricles start.
• Effect: This delay allows the ventricles to fill with blood from the atria.

Question 4

Bundle of His

• Location = ?
• Function = ?
• Effect = ?

Answer 4

Bundle of His:

• Location: In the septum (the wall) between the ventricles.
• Function: The bundle of His carries the electrical impulse from the AV node down to the ventricles.
• Effect: It splits into right and left bundle branches to direct the impulse to both ventricles.

Question 5

Bundle Branches

• Location = ?
• Function = ?
• Effect = ?

Answer 5

Bundle Branches:

• Location: In the septum, splitting towards the right and left ventricles.
• Function: These branches carry the impulse to the Purkinje fibers.
• Effect: They ensure the impulse reaches both ventricles efficiently.

Question 6

Purkinje Fibers

• Location = ?
• Function = ?
• Effect = ?

Answer 6

Purkinje Fibers:

• Location: Spread throughout the ventricles.
• Function: The Purkinje fibers distribute the electrical impulse throughout the ventricles.
• Effect: This causes the ventricles to contract, pumping blood out of the heart: the right ventricle sends blood to the lungs, and the left ventricle sends blood to the rest of the body.

Question 7

P Wave = ?

Answer 7

P Wave

• Representation: The P wave on an electrocardiogram (ECG or EKG) represents atrial depolarization.
• Depolarization: This is the process where the electrical impulse causes the atria (the upper chambers of the heart) to contract.
• Function: When the atria depolarize, they contract and push blood into the ventricles (the lower chambers of the heart).

Question 8

QRS Complex = ?

Answer 8

QRS Complex:

• What it Shows: Ventricular depolarization (contraction of the ventricles).

Detail: It includes three parts:

• Q Wave: A small downward deflection.
• R Wave: A large upward deflection.
• S Wave: A downward deflection following the R wave.

Question 9

T Wave = ?

Answer 9

T Wave:

• What it Shows: Ventricular repolarization (relaxation of the ventricles).
• Detail: It indicates the ventricles are resetting electrically and preparing for the next contraction.

Question 10

PR Interval = ?

Answer 10

PR Interval:

• What it Shows: The time from the beginning of atrial depolarization (start of P wave) to the beginning of ventricular depolarization (start of QRS complex).
• Detail: It represents the time the electrical impulse takes to travel from the SA node through the AV node and into the ventricles.

Question 11

ST Segment = ?

Answer 11

ST Segment:

• What it Shows: The time between the end of ventricular depolarization (end of QRS complex) and the beginning of ventricular repolarization (start of T wave).
• Detail: It is a flat, isoelectric line on the ECG.

Question 12

Lung Lobes

Review

Answer 12