CSC CSC Cardiac Anatomy & Physiology 2 — Questions and Answers
Question 1: Which layer of the heart wall contains the cardiac muscle cells responsible for contraction?
- Epicardium
- Pericardium
- Myocardium (Correct answer)
- Endocardium
Correct answer: Myocardium
The myocardium is the middle muscular layer of the heart wall and is responsible for the contractile force of each heartbeat.
Question 2: The sinoatrial (SA) node is located in the:
- Left ventricle
- Right atrium near the superior vena cava (Correct answer)
- Interventricular septum
- Left atrium near the pulmonary veins
Correct answer: Right atrium near the superior vena cava
The SA node, the heart's primary pacemaker, is located in the right atrium near the junction with the superior vena cava.
Question 3: Preload is best defined as:
- Resistance against which the ventricle ejects blood
- Ventricular wall tension during contraction
- End-diastolic volume or ventricular filling pressure (Correct answer)
- Heart rate times stroke volume
Correct answer: End-diastolic volume or ventricular filling pressure
Preload refers to the ventricular end-diastolic volume (or pressure), representing the stretch on myocardial fibers before contraction.
Question 4: Afterload refers to:
- The force of myocardial contraction
- The resistance the ventricle must overcome to eject blood (Correct answer)
- The ventricular filling pressure
- The heart rate during exercise
Correct answer: The resistance the ventricle must overcome to eject blood
Afterload is the resistance (primarily systemic vascular resistance) that the ventricle must overcome to eject blood into the aorta.
Question 5: The interventricular septum separates:
- The two atria
- The right and left ventricles (Correct answer)
- The atria from the ventricles
- The aorta from the pulmonary artery
Correct answer: The right and left ventricles
The interventricular septum is the muscular/membranous wall dividing the right and left ventricles.
Question 6: Which structure prevents backflow of blood from the aorta into the left ventricle?
- Mitral valve
- Tricuspid valve
- Pulmonic valve
- Aortic valve (Correct answer)
Correct answer: Aortic valve
The aortic valve prevents backflow from the aorta into the left ventricle during diastole by closing when aortic pressure exceeds ventricular pressure.
CSC CSC Cardiac Anatomy & Physiology 2
Which layer of the heart wall contains the cardiac muscle cells responsible for contraction?