The nurse is reviewing the sequence of the cardiac cycle. The nurse recognizes that the electrical stimulus of the cardiac cycle follows which sequence?
AV node-SA node bundle of His- bundle branches
SA node- AV node-bundle of His -bundle branches
Bundle of His- AV node- SA node- Erb's Point
AV node-SA node-bundle of His- Erb's Point
The Correct Answer is B
A. AV node - SA node - bundle of His - bundle branches:
This sequence is incorrect. The SA node (sinoatrial node) initiates the electrical impulse in the heart, followed by the AV node (atrioventricular node), bundle of His, and then the bundle branches.
B. SA node - AV node - bundle of His - bundle branches:
This sequence is correct. The electrical stimulus of the cardiac cycle starts at the SA node, which is the natural pacemaker of the heart. From the SA node, the impulse travels to the AV node, then to the bundle of His, and finally to the bundle branches, which distribute the impulse to the ventricles, causing them to contract.
C. Bundle of His - AV node - SA node - Erb's Point:
This sequence is incorrect. Erb's Point is a point on the chest where heart sounds S2 and S3 can be heard most distinctly.
D. AV node - SA node - bundle of His - Erb's Point:
This sequence is incorrect. The AV node comes after the SA node in the electrical conduction system of the heart. Erb's Point is not a part of the normal cardiac conduction pathway; it is a location for auscultation on the chest.
Nursing Test Bank
Naxlex Comprehensive Predictor Exams
Related Questions
Correct Answer is A
Explanation
A. Atelectatic crackles that do not have a pathologic cause:
Atelectatic crackles are short, popping, crackling sounds heard during auscultation. They occur in individuals who are in a supine position and disappear after a few breaths. These crackles are not indicative of any pathological condition; they are common when the lungs are not fully aerated, especially when a person is lying down.
B. Vesicular breath sounds:
Vesicular breath sounds are normal lung sounds heard over the peripheral lung areas. They are soft, low-pitched, and continuous throughout inspiration and part of expiration. Vesicular breath sounds are the typical sounds heard during routine breathing and are not associated with crackling or popping noises.
C. Fine wheezes:
Wheezes are high-pitched whistling sounds heard during expiration. They occur due to narrowed airways and are commonly associated with conditions like asthma or bronchoconstriction. Fine wheezes suggest a partial obstruction in the smaller airways, causing turbulent airflow, leading to the characteristic sound.
D. Fine crackles and may be a sign of pneumonia:
Fine crackles are high-pitched, discontinuous, crackling sounds heard during inspiration. They can occur due to the sudden opening of small airways, and their presence may indicate fluid in the lungs or lung inflammation. Fine crackles are often associated with conditions such as pneumonia, heart failure, or interstitial lung diseases.
Correct Answer is A
Explanation
A. The third heart sound (S3):
The third heart sound (S3) is an abnormal heart sound that occurs during early diastole, immediately after S2 (the second heart sound). It is caused by the rapid filling of the ventricles and is often associated with conditions like heart failure. In heart failure, the ventricles become stiff, causing vibrations that produce the S3 sound.
B. A friction rub:
A friction rub is a high-pitched, scratchy sound heard during both systole and diastole. It is caused by the rubbing together of inflamed pericardial layers (pericarditis) and is usually heard best at the left lower sternal border. Friction rubs can indicate pericardial inflammation and are often heard in conditions such as pericarditis or after a myocardial infarction.
C. The fourth heart sound (S4):
The fourth heart sound (S4) occurs late in diastole, just before S1, and is caused by atrial contraction. It is associated with increased resistance to ventricular filling, often due to conditions like hypertension or aortic stenosis. The S4 sound is heard as a low-pitched "atrial gallop."
D. A split second heart sound S2:
The second heart sound (S2) represents the closure of the aortic and pulmonic valves. Normally, S2 has two components: A2 (aortic valve closure) and P2 (pulmonic valve closure). A split S2 occurs when A2 and P2 do not close simultaneously. A physiological split S2 is common during inspiration and occurs due to delayed closure of the pulmonic valve. An abnormal or fixed split S2 can indicate underlying heart conditions such as atrial septal defect (ASD) or right bundle branch block (RBBB).
Whether you are a student looking to ace your exams or a practicing nurse seeking to enhance your expertise , our nursing education contents will empower you with the confidence and competence to make a difference in the lives of patients and become a respected leader in the healthcare field.
Visit Naxlex, invest in your future and unlock endless possibilities with our unparalleled nursing education contents today
Report Wrong Answer on the Current Question
Do you disagree with the answer? If yes, what is your expected answer? Explain.
Kindly be descriptive with the issue you are facing.