CRAT Cardiac Anatomy and Physiology 3

Question 1

The PR interval on the ECG reflects conduction through which structures?

Accepted Answer

Atria, AV node, and bundle of His

Answer

SA node only

Answer

Bundle branches and Purkinje fibers

Answer

Ventricular myocardium

Question 2

Which cells in the heart have the property of automaticity, meaning they can spontaneously depolarize?

Accepted Answer

Pacemaker cells in the SA node, AV node, and His-Purkinje system

Answer

Only SA node cells

Answer

Ventricular muscle cells only

Answer

All cardiac muscle cells equally

Question 3

In the normal cardiac conduction sequence, what is the correct order of activation?

Accepted Answer

SA node → atria → AV node → bundle of His → bundle branches → Purkinje fibers → ventricles

Answer

AV node → SA node → bundle branches → ventricles

Answer

SA node → AV node → atria → ventricles

Answer

Bundle branches → AV node → SA node → atria

Question 4

Depolarization of cardiac muscle cells occurs primarily due to rapid influx of which ion?

Accepted Answer

Sodium (Na+)

Answer

Potassium (K+)

Answer

Calcium (Ca2+)

Answer

Chloride (Cl-)

Question 5

Which layer of the heart is responsible for the electrical-to-mechanical coupling that produces contraction?

Accepted Answer

Myocardium

Answer

Endocardium

Answer

Epicardium

Answer

Pericardium

Question 6

What does the ST segment on the ECG represent?

Accepted Answer

The period between ventricular depolarization and repolarization (plateau phase)

Answer

Atrial repolarization

Answer

AV nodal delay

Answer

Ventricular filling