CCI Cardiac Anatomy and Physiology 4 — Questions and Answers
Question 1: The bundle of His bifurcates into the right and left bundle branches at which anatomical location?
- Base of the aortic valve
- Apex of the AV node
- Top of the muscular interventricular septum (Correct answer)
- Crux of the heart
Correct answer: Top of the muscular interventricular septum
The bundle of His travels through the fibrous AV septum and divides into right and left bundle branches at the crest of the muscular interventricular septum.
Question 2: Which great vessel arises from the right ventricle and carries deoxygenated blood?
- Aorta
- Superior vena cava
- Pulmonary artery (Correct answer)
- Pulmonary vein
Correct answer: Pulmonary artery
The pulmonary artery (main pulmonary trunk) originates from the right ventricular outflow tract and carries deoxygenated blood to the lungs for gas exchange.
Question 3: Ejection fraction (EF) is defined as:
- End-diastolic volume minus end-systolic volume
- Stroke volume divided by end-diastolic volume (Correct answer)
- Cardiac output divided by heart rate
- Stroke volume multiplied by systemic vascular resistance
Correct answer: Stroke volume divided by end-diastolic volume
Ejection fraction = stroke volume / end-diastolic volume × 100%; normal LV EF is ≥55%, and it reflects the percentage of blood ejected per beat.
Question 4: Which ion is primarily responsible for the plateau (phase 2) of the ventricular action potential?
- Potassium (K⁺)
- Sodium (Na⁺)
- Chloride (Cl⁻)
- Calcium (Ca²⁺) (Correct answer)
Correct answer: Calcium (Ca²⁺)
During phase 2 (plateau), slow L-type calcium channels open, allowing Ca²⁺ influx that balances K⁺ efflux and sustains depolarization, triggering excitation-contraction coupling.
Question 5: The left circumflex artery typically supplies which portion of the left ventricle?
- Anterior wall and apex
- Inferior wall and posterior descending territory
- Lateral wall and posterior wall (Correct answer)
- Interventricular septum
Correct answer: Lateral wall and posterior wall
The left circumflex artery courses in the left AV groove and typically supplies the lateral and posterior walls of the left ventricle via obtuse marginal branches.
Question 6: Which autonomic receptor mediates the positive chronotropic (rate-increasing) effect of catecholamines on the SA node?
- Muscarinic M2 receptor
- Alpha-1 adrenergic receptor
- Beta-1 adrenergic receptor (Correct answer)
- Beta-2 adrenergic receptor
Correct answer: Beta-1 adrenergic receptor
Beta-1 adrenergic receptors predominate in the SA node; stimulation by norepinephrine or epinephrine increases the rate of spontaneous depolarization, raising heart rate.
Question 7: The normal pulmonary capillary wedge pressure (PCWP) reflects pressure in which cardiac chamber?
- Right atrium
- Right ventricle
- Left atrium (Correct answer)
- Left ventricle end-diastole
Correct answer: Left atrium
When the pulmonary artery catheter balloon is wedged, forward flow stops and the pressure equilibrates with left atrial pressure through the pulmonary veins.
CCI Cardiac Anatomy and Physiology 4
The bundle of His bifurcates into the right and left bundle branches at which anatomical location?