1
BIOS255 / BIOS 255 Anatomy and Physiology III with
Lab Exam 1 Actual Exam 2026/2027 – Complete
Exam-Style Questions with Detailed Rationales | 100%
Verified – Pass Guaranteed – A+ Graded
Section 1: Cardiovascular System - Heart Anatomy & Electrical Activity (Questions 1-20)
Q1: Which layer of the heart wall is composed of simple squamous epithelium and covers the
heart valves and lines the chambers?
A. Epicardium
B. Myocardium
C. Endocardium
D. Pericardium
C. Endocardium [CORRECT]
Rationale: The endocardium is the innermost layer of the heart, consisting of endothelium that
provides a smooth surface for blood flow and lines the chambers and valves. The epicardium is
the visceral layer of the pericardium, and the myocardium is the muscular layer.
Correct Answer: C
Q2: The apex of the heart is located approximately at the level of the:
A. Second intercostal space, right of the sternum.
B. Fourth intercostal space, left of the sternum.
C. Fifth intercostal space, left midclavicular line.
D. Sixth intercostal space, right midclavicular line.
C. Fifth intercostal space, left midclavicular line. [CORRECT]
Rationale: The apex of the heart is the pointed, inferior end of the heart, formed by the tip of the
left ventricle. It is located in the fifth intercostal space, medial to the midclavicular line.
Correct Answer: C
,2
Q3: Which coronary artery supplies blood to the right atrium, right ventricle, and the SA and AV
nodes in the majority of the population?
A. Left Anterior Descending (LAD) artery
B. Circumflex artery
C. Right Coronary Artery (RCA)
D. Left Marginal artery
C. Right Coronary Artery (RCA) [CORRECT]
Rationale: The RCA supplies the right side of the heart. In about 90% of people (right dominant),
it branches into the Posterior Descending Artery (PDA) which supplies the AV node.
Correct Answer: C
Q4: Deoxygenated blood returns to the right atrium via the superior vena cava, inferior vena
cava, and the:
A. Pulmonary veins
B. Coronary sinus
C. Azygos vein
D. Great cardiac vein
B. Coronary sinus [CORRECT]
Rationale: The coronary sinus drains venous blood from the heart muscle (myocardium) directly
into the right atrium. Pulmonary veins carry oxygenated blood.
Correct Answer: B
Q5: The function of the chordae tendineae and papillary muscles is to:
A. Initiate the heartbeat.
B. Prevent the atrioventricular (AV) valves from everting into the atria during ventricular systole.
C. Open the semilunar valves.
D. Conduct electrical impulses to the ventricles.
B. Prevent the atrioventricular (AV) valves from everting into the atria during ventricular systole.
[CORRECT]
, 3
Rationale: When the ventricles contract, pressure rises. The chordae tendineae anchor the AV
valve cusps to the papillary muscles, preventing them from flipping backward into the atria
(prolapse).
Correct Answer: B
Q16: Which component of an intercalated disc allows for the direct passage of ions between
cardiac muscle cells, ensuring the heart contracts as a functional syncytium?
A. Desmosomes
B. Gap junctions
C. Tight junctions
D. Fascia adherens
B. Gap junctions [CORRECT]
Rationale: Gap junctions are low-resistance pathways that allow ions to pass freely from cell to
cell, enabling rapid electrical coupling and synchronized contraction. Desmosomes provide
mechanical strength.
Correct Answer: B
Q7: The "pacemaker" of the heart, which normally sets the heart rate, is the:
A. Atrioventricular (AV) node
B. Sinoatrial (SA) node
C. Bundle of His
D. Purkinje fibers
B. Sinoatrial (SA) node [CORRECT]
Rationale: The SA node, located in the superior right atrium, has the fastest rate of spontaneous
depolarization (60-100 bpm) and normally dictates the rhythm for the entire heart.
Correct Answer: B
Q8: If the SA node fails, which structure is most likely to take over as the pacemaker?
A. Purkinje fibers (20-40 bpm)
BIOS255 / BIOS 255 Anatomy and Physiology III with
Lab Exam 1 Actual Exam 2026/2027 – Complete
Exam-Style Questions with Detailed Rationales | 100%
Verified – Pass Guaranteed – A+ Graded
Section 1: Cardiovascular System - Heart Anatomy & Electrical Activity (Questions 1-20)
Q1: Which layer of the heart wall is composed of simple squamous epithelium and covers the
heart valves and lines the chambers?
A. Epicardium
B. Myocardium
C. Endocardium
D. Pericardium
C. Endocardium [CORRECT]
Rationale: The endocardium is the innermost layer of the heart, consisting of endothelium that
provides a smooth surface for blood flow and lines the chambers and valves. The epicardium is
the visceral layer of the pericardium, and the myocardium is the muscular layer.
Correct Answer: C
Q2: The apex of the heart is located approximately at the level of the:
A. Second intercostal space, right of the sternum.
B. Fourth intercostal space, left of the sternum.
C. Fifth intercostal space, left midclavicular line.
D. Sixth intercostal space, right midclavicular line.
C. Fifth intercostal space, left midclavicular line. [CORRECT]
Rationale: The apex of the heart is the pointed, inferior end of the heart, formed by the tip of the
left ventricle. It is located in the fifth intercostal space, medial to the midclavicular line.
Correct Answer: C
,2
Q3: Which coronary artery supplies blood to the right atrium, right ventricle, and the SA and AV
nodes in the majority of the population?
A. Left Anterior Descending (LAD) artery
B. Circumflex artery
C. Right Coronary Artery (RCA)
D. Left Marginal artery
C. Right Coronary Artery (RCA) [CORRECT]
Rationale: The RCA supplies the right side of the heart. In about 90% of people (right dominant),
it branches into the Posterior Descending Artery (PDA) which supplies the AV node.
Correct Answer: C
Q4: Deoxygenated blood returns to the right atrium via the superior vena cava, inferior vena
cava, and the:
A. Pulmonary veins
B. Coronary sinus
C. Azygos vein
D. Great cardiac vein
B. Coronary sinus [CORRECT]
Rationale: The coronary sinus drains venous blood from the heart muscle (myocardium) directly
into the right atrium. Pulmonary veins carry oxygenated blood.
Correct Answer: B
Q5: The function of the chordae tendineae and papillary muscles is to:
A. Initiate the heartbeat.
B. Prevent the atrioventricular (AV) valves from everting into the atria during ventricular systole.
C. Open the semilunar valves.
D. Conduct electrical impulses to the ventricles.
B. Prevent the atrioventricular (AV) valves from everting into the atria during ventricular systole.
[CORRECT]
, 3
Rationale: When the ventricles contract, pressure rises. The chordae tendineae anchor the AV
valve cusps to the papillary muscles, preventing them from flipping backward into the atria
(prolapse).
Correct Answer: B
Q16: Which component of an intercalated disc allows for the direct passage of ions between
cardiac muscle cells, ensuring the heart contracts as a functional syncytium?
A. Desmosomes
B. Gap junctions
C. Tight junctions
D. Fascia adherens
B. Gap junctions [CORRECT]
Rationale: Gap junctions are low-resistance pathways that allow ions to pass freely from cell to
cell, enabling rapid electrical coupling and synchronized contraction. Desmosomes provide
mechanical strength.
Correct Answer: B
Q7: The "pacemaker" of the heart, which normally sets the heart rate, is the:
A. Atrioventricular (AV) node
B. Sinoatrial (SA) node
C. Bundle of His
D. Purkinje fibers
B. Sinoatrial (SA) node [CORRECT]
Rationale: The SA node, located in the superior right atrium, has the fastest rate of spontaneous
depolarization (60-100 bpm) and normally dictates the rhythm for the entire heart.
Correct Answer: B
Q8: If the SA node fails, which structure is most likely to take over as the pacemaker?
A. Purkinje fibers (20-40 bpm)
