What is the primary function of the myocardium?
To contract and generate force for blood circulation
To produce pericardial fluid
To protect the heart from external injury
To facilitate the electrical conduction in the heart
The Correct Answer is A
A. To contract and generate force for blood circulation:
The myocardium is the muscular layer of the heart wall responsible for contracting and generating pressure to circulate blood through the systemic and pulmonary circuits. Its thickness varies by chamber, with the left ventricle being the thickest due to the higher pressure required to pump blood systemically. Dysfunction in the myocardium leads to heart failure or arrhythmias.
B. To produce pericardial fluid:
The pericardium, not the myocardium, secretes pericardial fluid to reduce friction during cardiac movement. Confusing these structures may lead to misunderstanding cardiac physiology.
C. To protect the heart from external injury:
Protection is primarily provided by the pericardium and thoracic cage. The myocardium’s main role is mechanical contraction, not external protection.
D. To facilitate the electrical conduction in the heart:
Electrical conduction is carried out by specialized nodes and fibers (SA node, AV node, bundle of His, Purkinje fibers). The myocardium responds to these signals but does not generate the primary conduction itself.
Nursing Test Bank
Naxlex Comprehensive Predictor Exams
Related Questions
Correct Answer is A
Explanation
A. They assist venous return to the heart, promoting cardiac output:
Skeletal muscle pumps play a critical role in assisting venous return. During physical activity, muscle contraction compresses veins, pushing blood toward the heart and increasing preload, which enhances stroke volume via the Frank-Starling mechanism. This indirectly supports blood pressure regulation by maintaining cardiac output.
B. They are the primary mechanism of blood pressure regulation:
Blood pressure is primarily regulated by the autonomic nervous system, baroreceptors, and vascular resistance. Skeletal muscle pumps assist venous return but are not the main regulatory mechanism for arterial pressure.
C. They control arterial blood pressure directly by contracting:
Skeletal muscle pumps act on veins, not arteries. They cannot directly control arterial blood pressure because arteries have thicker muscular walls and are regulated by vascular tone, not skeletal muscle contraction.
D. They regulate arterial constriction during physical activity:
Arterial constriction is controlled by smooth muscle in the arterial walls, influenced by the sympathetic nervous system, not by skeletal muscle activity.
Correct Answer is C
Explanation
A. S3:
S3 occurs during rapid ventricular filling in early diastole and may indicate volume overload or heart failure. It is not related to valve closure.
B. S1:
S1 corresponds to the closure of the atrioventricular (mitral and tricuspid) valves at the beginning of systole.
C. S2:
S2 occurs at the closure of the semilunar valves (aortic and pulmonic) at the end of systole, marking the onset of ventricular diastole. It is best heard at the base of the heart and is the normal “dub” sound.
D. S4:
S4 occurs during atrial contraction at the end of diastole and is associated with a stiff or hypertrophic ventricle. It is not a normal sound and does not correspond to semilunar valve closure.
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.