BIOS 255/BIOS255 Anatomy and Physiology III Complete
Guide Actual 2026/2027 with Detailed Rationales | 100%
Verified | Pass Guaranteed
SECTION 1: CARDIOVASCULAR SYSTEM – HEART ANATOMY &
PHYSIOLOGY (20 Questions)
Q1: The apex of the heart is located at which anatomical landmark?
A. The level of the second rib
B. The left fifth intercostal space at the midclavicular line
C. The sternal angle
D. The right third intercostal space
Correct Answer: B
Rationale: Correct because the cardiac apex is formed by the left ventricle and projects
to the left fifth intercostal space at the midclavicular line. Correct because this is the
standard auscultation point for the apical pulse.
Q2: Which heart valve prevents backflow of blood from the right ventricle into the right
atrium?
A. Pulmonary semilunar valve
B. Aortic semilunar valve
C. Tricuspid valve
D. Bicuspid (mitral) valve
Correct Answer: C
,Rationale: Correct because the tricuspid valve is the right atrioventricular valve that
closes during ventricular systole to prevent regurgitation into the right atrium. Correct
because this matches the anatomical position and function of right-sided AV valves.
Q3: During ventricular systole, which chamber generates the highest pressure?
A. Right atrium
B. Left atrium
C. Right ventricle
D. Left ventricle
Correct Answer: D
Rationale: Correct because the left ventricle must generate systemic pressure
(approximately 120 mmHg) to pump blood through the high-resistance systemic circuit.
Correct because this is 4-6 times greater than right ventricular pressure needed for the
pulmonary circuit.
Q4: The sinoatrial (SA) node is located in which anatomical region?
A. The interventricular septum near the apex
B. The wall of the right atrium near the superior vena cava opening
C. The wall of the left atrium near the pulmonary veins
D. The base of the aorta
Correct Answer: B
Rationale: Correct because the SA node is embedded in the posterior wall of the right
atrium near the opening of the superior vena cava. Correct because this location allows
the pacemaker to initiate depolarization that spreads across both atria.
Q5: On a standard EKG, the P wave represents which electrical event?
,A. Ventricular depolarization
B. Atrial depolarization
C. Ventricular repolarization
D. Atrial repolarization
Correct Answer: B
Rationale: Correct because the P wave represents atrial depolarization, which initiates
atrial contraction. Correct because atrial repolarization is masked by the QRS complex
due to its smaller electrical magnitude.
Q6: The QRS complex on an EKG corresponds to which mechanical event?
A. Atrial contraction
B. Isovolumetric ventricular contraction
C. Ventricular ejection
D. Ventricular relaxation
Correct Answer: B
Rationale: Correct because the QRS complex represents ventricular depolarization,
which triggers the beginning of ventricular systole and the isovolumetric contraction
phase. Correct because this precedes the opening of semilunar valves and ejection.
Q7: Which ion influx is primarily responsible for the rapid depolarization phase (Phase 0)
of the cardiac action potential in contractile cells?
A. Calcium influx through L-type channels
B. Sodium influx through fast voltage-gated channels
C. Potassium efflux through delayed rectifier channels
D. Chloride influx
Correct Answer: B
, Rationale: Correct because fast voltage-gated sodium channels open during Phase 0,
causing rapid depolarization to +30 mV in contractile cardiac cells. Correct because this
matches the ionic basis of ventricular and atrial muscle cell depolarization.
Q8: In a patient with heart rate 75 bpm, what is the approximate duration of one
complete cardiac cycle?
A. 0.5 seconds
B. 0.8 seconds
C. 1.0 seconds
D. 1.2 seconds
Correct Answer: B
Rationale: Correct because cardiac cycle duration is calculated as 60 seconds divided
by heart rate (60/75 = 0.8 seconds). Correct because at 75 bpm, systole occupies
approximately 0.27 seconds and diastole 0.53 seconds.
Q9: Which factor is the primary determinant of stroke volume during exercise?
A. Heart rate
B. Venous return (preload)
C. Systemic vascular resistance
D. Blood viscosity
Correct Answer: B
Rationale: Correct because increased venous return during exercise stretches cardiac
muscle fibers (Frank-Starling mechanism), increasing contractile force and stroke
volume. Correct because this is the dominant mechanism for augmenting cardiac
output during physical activity.
Guide Actual 2026/2027 with Detailed Rationales | 100%
Verified | Pass Guaranteed
SECTION 1: CARDIOVASCULAR SYSTEM – HEART ANATOMY &
PHYSIOLOGY (20 Questions)
Q1: The apex of the heart is located at which anatomical landmark?
A. The level of the second rib
B. The left fifth intercostal space at the midclavicular line
C. The sternal angle
D. The right third intercostal space
Correct Answer: B
Rationale: Correct because the cardiac apex is formed by the left ventricle and projects
to the left fifth intercostal space at the midclavicular line. Correct because this is the
standard auscultation point for the apical pulse.
Q2: Which heart valve prevents backflow of blood from the right ventricle into the right
atrium?
A. Pulmonary semilunar valve
B. Aortic semilunar valve
C. Tricuspid valve
D. Bicuspid (mitral) valve
Correct Answer: C
,Rationale: Correct because the tricuspid valve is the right atrioventricular valve that
closes during ventricular systole to prevent regurgitation into the right atrium. Correct
because this matches the anatomical position and function of right-sided AV valves.
Q3: During ventricular systole, which chamber generates the highest pressure?
A. Right atrium
B. Left atrium
C. Right ventricle
D. Left ventricle
Correct Answer: D
Rationale: Correct because the left ventricle must generate systemic pressure
(approximately 120 mmHg) to pump blood through the high-resistance systemic circuit.
Correct because this is 4-6 times greater than right ventricular pressure needed for the
pulmonary circuit.
Q4: The sinoatrial (SA) node is located in which anatomical region?
A. The interventricular septum near the apex
B. The wall of the right atrium near the superior vena cava opening
C. The wall of the left atrium near the pulmonary veins
D. The base of the aorta
Correct Answer: B
Rationale: Correct because the SA node is embedded in the posterior wall of the right
atrium near the opening of the superior vena cava. Correct because this location allows
the pacemaker to initiate depolarization that spreads across both atria.
Q5: On a standard EKG, the P wave represents which electrical event?
,A. Ventricular depolarization
B. Atrial depolarization
C. Ventricular repolarization
D. Atrial repolarization
Correct Answer: B
Rationale: Correct because the P wave represents atrial depolarization, which initiates
atrial contraction. Correct because atrial repolarization is masked by the QRS complex
due to its smaller electrical magnitude.
Q6: The QRS complex on an EKG corresponds to which mechanical event?
A. Atrial contraction
B. Isovolumetric ventricular contraction
C. Ventricular ejection
D. Ventricular relaxation
Correct Answer: B
Rationale: Correct because the QRS complex represents ventricular depolarization,
which triggers the beginning of ventricular systole and the isovolumetric contraction
phase. Correct because this precedes the opening of semilunar valves and ejection.
Q7: Which ion influx is primarily responsible for the rapid depolarization phase (Phase 0)
of the cardiac action potential in contractile cells?
A. Calcium influx through L-type channels
B. Sodium influx through fast voltage-gated channels
C. Potassium efflux through delayed rectifier channels
D. Chloride influx
Correct Answer: B
, Rationale: Correct because fast voltage-gated sodium channels open during Phase 0,
causing rapid depolarization to +30 mV in contractile cardiac cells. Correct because this
matches the ionic basis of ventricular and atrial muscle cell depolarization.
Q8: In a patient with heart rate 75 bpm, what is the approximate duration of one
complete cardiac cycle?
A. 0.5 seconds
B. 0.8 seconds
C. 1.0 seconds
D. 1.2 seconds
Correct Answer: B
Rationale: Correct because cardiac cycle duration is calculated as 60 seconds divided
by heart rate (60/75 = 0.8 seconds). Correct because at 75 bpm, systole occupies
approximately 0.27 seconds and diastole 0.53 seconds.
Q9: Which factor is the primary determinant of stroke volume during exercise?
A. Heart rate
B. Venous return (preload)
C. Systemic vascular resistance
D. Blood viscosity
Correct Answer: B
Rationale: Correct because increased venous return during exercise stretches cardiac
muscle fibers (Frank-Starling mechanism), increasing contractile force and stroke
volume. Correct because this is the dominant mechanism for augmenting cardiac
output during physical activity.
