,1. What is the primary pacemaker of the heart?
A. Sinoatrial node
B. Atrioventricular node
C. Purkinje fibers
D. Bundle of His
Answer: A. Sinoatrial node
Rationale: The sinoatrial node is responsible for initiating the electrical
impulse that sets the rhythm of the heart, making it the primary
pacemaker.
2. Which structure is responsible for the delay in electrical conduction,
allowing for proper atrial contraction before ventricular contraction?
A. Sinoatrial node
B. Atrioventricular node
C. Purkinje fibers
D. Bundle of His
Answer: B. Atrioventricular node
Rationale: The atrioventricular node delays the electrical signal from the
sinoatrial node, providing time for the atria to contract and fill the
ventricles with blood before they contract.
3. What is the correct sequence of electrical conduction in the heart?
A. AV node → SA node → Bundle of His → Purkinje fibers
B. SA node → AV node → Bundle of His → Purkinje fibers
C. Purkinje fibers → SA node → AV node → Bundle of His
D. Bundle of His → Purkinje fibers → SA node → AV node
Answer: B. SA node → AV node → Bundle of His → Purkinje fibers
Rationale: The electrical impulse normally starts at the SA node, then
travels to the AV node, through the Bundle of His, and finally through the
Purkinje fibers to cause muscle contraction.
Which of the following represents the correct placement of the electrodes
for a standard 12-lead ECG?
A. V1: 4th intercostal space, right sternal border
B. V3: 5th intercostal space, midclavicular line
C. V5: 6th intercostal space, midaxillary line
, D. Lead II: Right sternal border
Answer: A. V1: 4th intercostal space, right sternal border
Rationale: Correct electrode placement is crucial for obtaining accurate
ECG recordings. V1 is typically placed in the 4th intercostal space along
the right sternal border.
The P wave on an ECG represents:
A. Atrial depolarization
B. Ventricular depolarization
C. Ventricular repolarization
D. Atrial repolarization
Answer: A. Atrial depolarization
Rationale: The P wave corresponds to atrial depolarization, indicating
the contraction of the atria.
Which ECG lead is best for detecting ST-segment changes indicative of
myocardial ischemia?
A. Lead I
B. Lead II
C. Lead III
D. V5
Answer: D. V5
Rationale: V5 is positioned to detect changes in the lateral wall of the
left ventricle, making it ideal for identifying ST-segment changes
associated with myocardial ischemia.
The QT interval on an ECG represents:
A. Atrial depolarization
B. Ventricular depolarization
C. Ventricular repolarization
D. Atrial repolarization
Answer: C. Ventricular repolarization
Rationale: The QT interval corresponds to ventricular repolarization,
indicating the recovery of the ventricles before the next contraction.
The benefits of buying summaries with Stuvia:
Guaranteed quality through customer reviews
Stuvia customers have reviewed more than 700,000 summaries. This how you know that you are buying the best documents.
Quick and easy check-out
You can quickly pay through credit card or Stuvia-credit for the summaries. There is no membership needed.
Focus on what matters
Your fellow students write the study notes themselves, which is why the documents are always reliable and up-to-date. This ensures you quickly get to the core!
Frequently asked questions
What do I get when I buy this document?
You get a PDF, available immediately after your purchase. The purchased document is accessible anytime, anywhere and indefinitely through your profile.
Satisfaction guarantee: how does it work?
Our satisfaction guarantee ensures that you always find a study document that suits you well. You fill out a form, and our customer service team takes care of the rest.
Who am I buying these notes from?
Stuvia is a marketplace, so you are not buying this document from us, but from seller ClemAcademia. Stuvia facilitates payment to the seller.
Will I be stuck with a subscription?
No, you only buy these notes for $12.49. You're not tied to anything after your purchase.