EKG certification Certification EKG Cardiac Anatomy & Physiology 1 — Questions and Answers
Question 1: Where is the sinoatrial (SA) node located in the heart?
- In the interatrial septum near the fossa ovalis
- In the upper right atrium near the opening of the superior vena cava (Correct answer)
- At the apex of the right ventricle
- Within the atrioventricular groove on the posterior surface
Correct answer: In the upper right atrium near the opening of the superior vena cava
The SA node sits in the upper wall of the right atrium, close to where the superior vena cava enters. It acts as the heart's primary pacemaker, initiating the electrical impulse that triggers each heartbeat.
Question 2: What does the QRS complex on an EKG primarily represent?
- Atrial depolarization
- Ventricular repolarization
- Ventricular depolarization (Correct answer)
- Conduction through the AV node
Correct answer: Ventricular depolarization
The QRS complex reflects the rapid electrical depolarization spreading through the ventricular myocardium, which triggers ventricular contraction. Atrial depolarization is represented by the P wave, while repolarization appears as the T wave.
Question 3: Which structure is responsible for delaying the electrical impulse between the atria and ventricles?
- Bundle of His
- Purkinje fibers
- Atrioventricular (AV) node (Correct answer)
- Right bundle branch
Correct answer: Atrioventricular (AV) node
The AV node, located in the lower interatrial septum, intentionally slows conduction to allow the atria to finish contracting and the ventricles to fill with blood before ventricular depolarization begins. This delay is visible as the PR segment on the EKG.
Question 4: The left ventricle has a thicker myocardial wall than the right ventricle primarily because it must:
- Receive blood from the pulmonary veins at higher pressure
- Pump blood against the high resistance of the systemic circulation (Correct answer)
- Filter blood before it enters the coronary arteries
- Generate electrical impulses for the entire heart
Correct answer: Pump blood against the high resistance of the systemic circulation
The left ventricle pumps oxygenated blood through the aorta to the entire systemic circulation, which has much higher vascular resistance than the pulmonary circuit. Greater wall thickness generates the force needed to overcome that resistance.
Question 5: Which vessels supply oxygenated blood directly to the myocardium?
- Pulmonary arteries
- Coronary arteries (Correct answer)
- Thebesian veins
- Thoracic aorta branches
Correct answer: Coronary arteries
The right and left coronary arteries arise from the aortic root just above the aortic valve and branch across the heart surface to deliver oxygenated blood to the myocardium itself. Impaired flow in these vessels is the basis of ischemic heart disease.
Question 6: On a normal EKG, the T wave represents:
- Atrial repolarization
- Ventricular depolarization
- Ventricular repolarization (Correct answer)
- Conduction through the bundle branches
Correct answer: Ventricular repolarization
After ventricular contraction, the myocardial cells must restore their resting electrical state — a process called repolarization. This recovery phase produces the T wave. Changes in T-wave morphology can indicate ischemia, electrolyte imbalances, or other cardiac pathology.
EKG certification Certification EKG Cardiac Anatomy & Physiology 1
Where is the sinoatrial (SA) node located in the heart?