Identify the component of the heart pointed to by the line.
The component is
Trabecular carneae
Pulmonary semilunar valve
Papillary muscles
Pectinate muscles
Chordae tendineae
Right atrium
The Correct Answer is F
Correct answer: F.
A. Trabeculae carneae: These are irregular, muscular ridges lining the inner walls of the ventricles. They prevent suction during contraction, aid in ventricular contraction efficiency, and contribute to overall cardiac structural integrity.
B. Pulmonary semilunar valve: This valve is located between the right ventricle and pulmonary artery. It prevents backflow of blood into the ventricle during diastole and ensures unidirectional pulmonary circulation toward the lungs.
C. Papillary muscles: Papillary muscles are conical projections of ventricular myocardium that anchor chordae tendineae. During ventricular contraction, they contract to prevent inversion or prolapse of atrioventricular valves, ensuring proper unidirectional blood flow.
D. Pectinate muscles: Pectinate muscles are comb-like muscular ridges in the atrial walls, particularly prominent in the right atrium. They enhance atrial contraction, increasing blood flow into the ventricles efficiently during systole.
E. Chordae tendineae: These are thin, fibrous cords connecting atrioventricular valve leaflets to papillary muscles. They prevent valve prolapse during ventricular contraction, maintaining proper closure and unidirectional blood flow from atria to ventricles.
F. Right atrium: It is located on the superior right side of the heart and receives deoxygenated blood from the superior vena cava, inferior vena cava, and coronary sinus. It forms the right border of the heart. Physiologically, the right atrium functions as a receiving chamber that collects systemic venous blood and delivers it through the tricuspid valve into the right ventricle during atrial contraction.
G. Bicuspid valve: Also called the mitral valve, it is located between the left atrium and left ventricle. It prevents backflow into the atrium during ventricular contraction, ensuring efficient systemic circulation.
H. Fossa ovalis: This is a depression in the interatrial septum, the remnant of the fetal foramen ovale. It allowed blood to bypass the fetal lungs and normally closes after birth.
I. Left ventricle: The left ventricle pumps oxygenated blood into the aorta under high pressure. Its thick muscular wall enables strong contractions necessary to sustain systemic circulation throughout the body.
J. Interventricular septum: This thick muscular wall separates the left and right ventricles. It prevents mixing of oxygenated and deoxygenated blood and contributes to the contractile force of ventricular systole.
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Naxlex Comprehensive Predictor Exams
Related Questions
Correct Answer is C
Explanation
A. Contractile force increases to compensate for the reduced cardiac output: In early compensatory phases, the heart may attempt to increase contractility via sympathetic stimulation, but in true heart failure, the myocardium is unable to generate sufficient force due to structural or functional impairment.
B. Contractile force increases, leading to an increased end systolic volume: Increased contractility would reduce, not increase, end-systolic volume because more blood is ejected per beat. In heart failure, contractile weakness leads to higher end-systolic volumes, reflecting incomplete emptying of the ventricles.
C. Contractile force is diminished due to damaged cardiomyocytes or cardiomyopathies: Heart failure results from conditions such as myocardial infarction, chronic hypertension, or dilated cardiomyopathy that impair cardiomyocyte function. This reduces the strength of ventricular contraction, decreasing stroke volume and overall cardiac output.
D. Contractile force is not affected in heart failure: Contractile force is significantly affected in heart failure. The weakened myocardium cannot generate sufficient pressure to maintain normal stroke volume, making this statement inaccurate.
E. Contractile force remains the same, but the heart becomes larger: While ventricular dilation can occur in chronic heart failure as a compensatory mechanism (eccentric hypertrophy), the contractile force per myocyte is reduced. Increased chamber size alone does not preserve effective contraction.
Correct Answer is A
Explanation
Correct answer: True
Surface electrodes placed on the skin at specific anatomical locations detect the electrical impulses generated by the heart during depolarization and repolarization. These electrodes capture changes in voltage as the cardiac conduction system, including the SA node, AV node, bundle branches, and Purkinje fibers, propagates impulses through the atria and ventricles. The collected signals are transmitted to an electrocardiograph, which records the heart’s electrical activity as an electrocardiogram (ECG or EKG). This test provides critical information about heart rate, rhythm, conduction pathways, and possible ischemic or structural cardiac abnormalities.
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