CET Cardiac Anatomy & Physiology 4

Question 1

Which ion rapidly entering a cardiac cell initiates the action potential upstroke (Phase 0)?

Accepted Answer

Sodium (Na+)

Answer

Phase 0 of the cardiac action potential is caused by rapid influx of sodium ions through fast Na+ channels, causing rapid depolarization.

Question 2

What does the PR interval on an ECG measure?

Accepted Answer

Time from atrial depolarization to the start of ventricular depolarization

Answer

The PR interval measures the conduction time from the start of atrial depolarization through the AV node to the onset of ventricular depolarization.

Question 3

Which structure forms the apex of the heart?

Accepted Answer

Left ventricle

Answer

The apex of the heart is formed by the left ventricle and points downward and to the left, typically at the 5th intercostal space.

Question 4

What is cardiac output defined as?

Accepted Answer

Heart rate multiplied by stroke volume

Answer

Cardiac output equals heart rate multiplied by stroke volume and represents the volume of blood the heart pumps per minute.

Question 5

The right coronary artery most commonly supplies which structure that controls heart rate?

Accepted Answer

SA node

Answer

In approximately 60% of people, the SA node is supplied by the SA nodal artery, which arises from the right coronary artery.

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