BIOL 252 Human Anatomy & Physiology II Lab Module 3
Exam Questions | 100% Correct Answers with Detailed
Rationales (2026/2027 Edition)
==============================
SECTION 1: Cardiovascular System
Question 1
Which layer of the heart wall contains the cardiac muscle fibers responsible for
contraction?
A. Epicardium
B. Myocardium
C. Endocardium
D. Pericardium
Correct Answer: B
Rationale: The myocardium is the thick middle layer of the heart wall composed of
cardiac muscle tissue (cardiomyocytes) that contracts to pump blood. The epicardium
(A) is the outer serous membrane, the endocardium (C) is the inner endothelial lining,
and the pericardium (D) is the fibrous sac surrounding the heart, not part of the heart
wall itself.
Question 2
During a laboratory exercise, a student records an ECG tracing. Which wave represents
atrial depolarization?
A. P wave
B. QRS complex
,C. T wave
D. U wave
Correct Answer: A
Rationale: The P wave on an ECG represents depolarization of the atria, initiated by the
sinoatrial (SA) node. The QRS complex (B) represents ventricular depolarization (and
atrial repolarization, which is masked). The T wave (C) represents ventricular
repolarization. The U wave (D), when present, may represent repolarization of the
Purkinje fibers or papillary muscles.
Question 3
A patient's cardiac output is measured at 5.0 L/min with a heart rate of 70 beats/min.
What is the patient's stroke volume?
A. 50 mL
B. 71 mL
C. 85 mL
D. 100 mL
Correct Answer: B
Rationale: Cardiac output (CO) = Heart rate (HR) × Stroke volume (SV). Therefore, SV =
CO ÷ HR = 5,000 mL/min ÷ 70 beats/min = 71.4 mL/beat. Normal stroke volume ranges
from 60-80 mL. This calculation is fundamental to understanding cardiovascular
physiology and interpreting hemodynamic measurements in laboratory and clinical
settings.
Question 4
,Which blood vessel type has the thickest tunica media relative to its lumen diameter,
allowing for the greatest vasoconstriction and vasodilation?
A. Large arteries
B. Arterioles
C. Capillaries
D. Venules
Correct Answer: B
Rationale: Arterioles have the highest ratio of smooth muscle in the tunica media to
lumen diameter, making them the primary resistance vessels that regulate blood flow
and systemic vascular resistance. While large arteries (A) have thick walls, their relative
smooth muscle content is lower. Capillaries (C) lack smooth muscle, and venules (D)
have minimal smooth muscle.
Question 5
A patient presents with a blood pressure of 165/98 mmHg. Which classification best
describes this reading according to current ACC/AHA guidelines?
A. Normal
B. Elevated
C. Stage 1 Hypertension
D. Stage 2 Hypertension
Correct Answer: D
Rationale: According to ACC/AHA 2017 guidelines, Stage 2 Hypertension is defined as
systolic blood pressure ≥140 mmHg or diastolic blood pressure ≥90 mmHg. This
patient's readings (165/98) exceed both thresholds. Stage 1 (C) is 130-139 systolic or
80-89 diastolic. Elevated (B) is 120-129 systolic with diastolic <80. Normal (A) is
<120/<80.
, Question 6
Which structure in the heart serves as the primary pacemaker, establishing the inherent
heart rate of approximately 75 beats per minute?
A. Atrioventricular (AV) node
B. Sinoatrial (SA) node
C. Bundle of His
D. Purkinje fibers
Correct Answer: B
Rationale: The sinoatrial (SA) node, located in the posterior wall of the right atrium near
the superior vena cava opening, is the primary pacemaker of the heart. It spontaneously
depolarizes at approximately 75 beats/min, establishing the normal sinus rhythm. The
AV node (A) acts as a secondary pacemaker (~40-60 bpm), while the Bundle of His (C)
and Purkinje fibers (D) conduct impulses but have slower intrinsic rates (~20-40 bpm).
Question 7
During a laboratory blood pressure exercise, a student inflates a sphygmomanometer to
180 mmHg and slowly releases pressure. The first Korotkoff sound is heard at 142
mmHg. What does this measurement represent?
A. Diastolic pressure
B. Mean arterial pressure
C. Systolic pressure
D. Pulse pressure
Correct Answer: C
Exam Questions | 100% Correct Answers with Detailed
Rationales (2026/2027 Edition)
==============================
SECTION 1: Cardiovascular System
Question 1
Which layer of the heart wall contains the cardiac muscle fibers responsible for
contraction?
A. Epicardium
B. Myocardium
C. Endocardium
D. Pericardium
Correct Answer: B
Rationale: The myocardium is the thick middle layer of the heart wall composed of
cardiac muscle tissue (cardiomyocytes) that contracts to pump blood. The epicardium
(A) is the outer serous membrane, the endocardium (C) is the inner endothelial lining,
and the pericardium (D) is the fibrous sac surrounding the heart, not part of the heart
wall itself.
Question 2
During a laboratory exercise, a student records an ECG tracing. Which wave represents
atrial depolarization?
A. P wave
B. QRS complex
,C. T wave
D. U wave
Correct Answer: A
Rationale: The P wave on an ECG represents depolarization of the atria, initiated by the
sinoatrial (SA) node. The QRS complex (B) represents ventricular depolarization (and
atrial repolarization, which is masked). The T wave (C) represents ventricular
repolarization. The U wave (D), when present, may represent repolarization of the
Purkinje fibers or papillary muscles.
Question 3
A patient's cardiac output is measured at 5.0 L/min with a heart rate of 70 beats/min.
What is the patient's stroke volume?
A. 50 mL
B. 71 mL
C. 85 mL
D. 100 mL
Correct Answer: B
Rationale: Cardiac output (CO) = Heart rate (HR) × Stroke volume (SV). Therefore, SV =
CO ÷ HR = 5,000 mL/min ÷ 70 beats/min = 71.4 mL/beat. Normal stroke volume ranges
from 60-80 mL. This calculation is fundamental to understanding cardiovascular
physiology and interpreting hemodynamic measurements in laboratory and clinical
settings.
Question 4
,Which blood vessel type has the thickest tunica media relative to its lumen diameter,
allowing for the greatest vasoconstriction and vasodilation?
A. Large arteries
B. Arterioles
C. Capillaries
D. Venules
Correct Answer: B
Rationale: Arterioles have the highest ratio of smooth muscle in the tunica media to
lumen diameter, making them the primary resistance vessels that regulate blood flow
and systemic vascular resistance. While large arteries (A) have thick walls, their relative
smooth muscle content is lower. Capillaries (C) lack smooth muscle, and venules (D)
have minimal smooth muscle.
Question 5
A patient presents with a blood pressure of 165/98 mmHg. Which classification best
describes this reading according to current ACC/AHA guidelines?
A. Normal
B. Elevated
C. Stage 1 Hypertension
D. Stage 2 Hypertension
Correct Answer: D
Rationale: According to ACC/AHA 2017 guidelines, Stage 2 Hypertension is defined as
systolic blood pressure ≥140 mmHg or diastolic blood pressure ≥90 mmHg. This
patient's readings (165/98) exceed both thresholds. Stage 1 (C) is 130-139 systolic or
80-89 diastolic. Elevated (B) is 120-129 systolic with diastolic <80. Normal (A) is
<120/<80.
, Question 6
Which structure in the heart serves as the primary pacemaker, establishing the inherent
heart rate of approximately 75 beats per minute?
A. Atrioventricular (AV) node
B. Sinoatrial (SA) node
C. Bundle of His
D. Purkinje fibers
Correct Answer: B
Rationale: The sinoatrial (SA) node, located in the posterior wall of the right atrium near
the superior vena cava opening, is the primary pacemaker of the heart. It spontaneously
depolarizes at approximately 75 beats/min, establishing the normal sinus rhythm. The
AV node (A) acts as a secondary pacemaker (~40-60 bpm), while the Bundle of His (C)
and Purkinje fibers (D) conduct impulses but have slower intrinsic rates (~20-40 bpm).
Question 7
During a laboratory blood pressure exercise, a student inflates a sphygmomanometer to
180 mmHg and slowly releases pressure. The first Korotkoff sound is heard at 142
mmHg. What does this measurement represent?
A. Diastolic pressure
B. Mean arterial pressure
C. Systolic pressure
D. Pulse pressure
Correct Answer: C
