Full Practice Questions on Sympathomimetics,
Antiarrhythmics, Vasodilators & Diuretics – Part III
Circulatory System (2026 Update) Questions with
Answers and Detailed Rationales
SECTION OVERVIEW
Chapter Topic Questions
Chapter 14 Circulatory Physiology 10
Chapter 15 Cardiac Physiology 10
Chapter 16 Renal Physiology 5
Chapter 17 Intravenous Fluids and Electrolytes 5
Chapter 18 Sympathomimetic Drugs 15
Chapter 19 Sympatholytics 10
Chapter 20 Vasodilators 5
Chapter 21 Antiarrhythmic Drugs 10
Chapter 22 Diuretics 5
,Chapter 14: Circulatory Physiology
10 Questions
1. A 65-year-old patient with controlled hypertension undergoes general
anesthesia. The anesthesia provider monitors blood pressure closely.
Which mechanism is PRIMARILY responsible for short-term blood
pressure regulation during anesthetic induction?
A) Renin-angiotensin-aldosterone system activation
B) Baroreceptor reflex mediated by the autonomic nervous system
C) Release of atrial natriuretic peptide
D) Capillary fluid shift mechanisms
Answer: B
Rationale: Short-term blood pressure regulation (seconds to minutes) is
primarily mediated by the baroreceptor reflex. Baroreceptors in the carotid
sinus and aortic arch detect changes in arterial pressure and trigger
autonomic adjustments—increasing sympathetic outflow during hypotension
and enhancing parasympathetic activity during hypertension . The renin-
angiotensin-aldosterone system (A) and atrial natriuretic peptide (C) are
involved in intermediate to long-term regulation. Capillary fluid shifts (D)
occur over hours.
,2. A patient under anesthesia has a measured mean arterial pressure
(MAP) of 60 mmHg. The calculated cardiac output is 4.0 L/min. What is
the systemic vascular resistance (SVR) in dynes·sec·cm⁻⁵?
A) 800
B) 1200
C) 1600
D) 2000
Answer: B
Rationale: SVR is calculated using the formula: SVR = (MAP - CVP) × 80 / CO.
Assuming CVP is 0 mmHg for calculation purposes: (60 - 0) × .0 = 60 ×
20 = 1200 dynes·sec·cm⁻⁵. Normal SVR range is 800-1200 dynes·sec·cm⁻⁵.
Option A (800) would require lower MAP or higher CO. Option C (1600) and D
(2000) indicate elevated SVR, which would require higher MAP or lower CO.
3. During positive pressure ventilation, the anesthetist notes a decrease
in cardiac output. Which mechanism BEST explains this observation?
A) Decreased vagal tone
B) Increased intrathoracic pressure reducing venous return
C) Direct myocardial depression from the ventilator
D) Reflex tachycardia
,Answer: B
Rationale: Positive pressure ventilation increases intrathoracic pressure,
which decreases the pressure gradient for venous return to the right heart
(reduced preload). This decrease in venous return leads to reduced right
ventricular filling and ultimately decreased cardiac output by the Frank-
Starling mechanism . Option A is incorrect—positive pressure ventilation does
not decrease vagal tone. Option C is incorrect—ventilators do not directly
depress myocardium. Option D (reflex tachycardia) may occur as a
compensatory response but does not explain the mechanism of decreased CO.
4. A patient with sepsis develops profound vasodilation. Which vascular
bed is MOST affected by this pathologic vasodilation?
A) Cerebral circulation
B) Coronary circulation
C) Splanchnic and musculoskeletal circulations
D) Pulmonary circulation
Answer: C
Rationale: In sepsis, inflammatory mediators cause widespread vasodilation,
particularly affecting the splanchnic and musculoskeletal vascular beds, which
have high baseline sympathetic tone and abundant adrenergic receptors.
Cerebral (A) and coronary (B) circulations have robust autoregulation and are
,relatively protected. Pulmonary circulation (D) may be affected but is not the
primary site of pathologic vasodilation in septic shock.
5. A patient under anesthesia develops hypotension. The baroreceptor
reflex should trigger which compensatory response?
A) Decreased heart rate
B) Increased parasympathetic outflow
C) Increased sympathetic outflow to heart and blood vessels
D) Decreased myocardial contractility
Answer: C
Rationale: The baroreceptor reflex responds to hypotension by decreasing
afferent firing from baroreceptors, which reduces inhibition of the vasomotor
center. This leads to increased sympathetic outflow and decreased
parasympathetic (vagal) tone. The result is increased heart rate, increased
myocardial contractility, and vasoconstriction—all working to restore blood
pressure . Options A, B, and D describe responses to hypertension, not
hypotension.
6. Which vascular bed exhibits the GREATEST capacity for
autoregulation independent of autonomic nervous input?
,A) Cutaneous circulation
B) Splanchnic circulation
C) Cerebral circulation
D) Renal medulla
Answer: C
Rationale: Cerebral circulation demonstrates the most robust autoregulation,
maintaining relatively constant blood flow across a wide range of mean
arterial pressures (approximately 50-150 mmHg) through metabolic and
myogenic mechanisms. This autoregulation is intrinsic to the cerebral vessels
and continues to function even after denervation . Cutaneous (A) and
splanchnic (B) circulations are heavily influenced by sympathetic tone. The
renal medulla (D) receives less blood flow than the cortex and has limited
autoregulation.
7. During hemorrhagic shock, the body preferentially maintains blood
flow to which organs?
A) Skin and skeletal muscle
B) Brain and heart
C) Kidneys and liver
D) Gastrointestinal tract
Answer: B
,Rationale: During hemorrhagic shock, sympathetic-mediated
vasoconstriction is not uniform. Vessels in the skin, skeletal muscle,
splanchnic bed, and kidneys constrict vigorously to redirect blood flow to the
most vital organs—the brain and heart—which have limited tolerance for
ischemia and possess robust autoregulation . This protective mechanism
prioritizes cerebral and coronary perfusion at the expense of other vascular
beds.
8. A patient on cardiopulmonary bypass has non-pulsatile flow. Which
physiologic effect is MOST concerning?
A) Decreased cerebral oxygen consumption
B) Impaired renal function from altered renal perfusion
C) Enhanced myocardial protection
D) Increased pulmonary vascular resistance
Answer: B
Rationale: Non-pulsatile flow during cardiopulmonary bypass can impair
renal function due to altered renal perfusion patterns, activation of the renin-
angiotensin-aldosterone system, and potential for renal medullary ischemia.
Pulsatile flow better preserves end-organ function, particularly in the kidneys.
Cerebral oxygen consumption (A) is not consistently decreased. Myocardial
protection (C) is achieved through cardioplegia, not pulsatility. Pulmonary
vascular resistance (D) is affected by multiple factors during bypass.
,9. Which statement accurately describes the relationship between blood
viscosity and vascular resistance?
A) Viscosity is inversely proportional to resistance
B) Viscosity has no effect on resistance
C) Viscosity is directly proportional to resistance (Poiseuille's law)
D) Viscosity affects only venous circulation
Answer: C
Rationale: According to Poiseuille's law, resistance to flow is directly
proportional to the viscosity of the fluid and the length of the tube, and
inversely proportional to the fourth power of the radius. Therefore, increased
blood viscosity (as occurs with polycythemia or hypothermia) directly
increases vascular resistance, particularly in the microcirculation . Options A
and B are incorrect. Option D is incorrect—viscosity affects all vessels.
10. A patient with an arteriovenous (AV) fistula for hemodialysis has
decreased systemic vascular resistance. This is BEST explained by:
A) Increased sympathetic tone
B) Direct shunting of blood from arteries to veins, bypassing capillary beds
C) Reduced cardiac output
D) Vasodilation from circulating factors
, Answer: B
Rationale: An AV fistula creates a direct connection between an artery and
vein, bypassing the high-resistance capillary bed. This low-resistance pathway
decreases overall systemic vascular resistance, which can lead to
compensatory increases in cardiac output. Over time, large AV fistulas can
result in high-output heart failure. Option A would increase SVR, not decrease
it. Option C is incorrect—CO often increases. Option D is not the primary
mechanism.
Chapter 15: Cardiac Physiology
10 Questions
11. Which phase of the cardiac action potential corresponds to the
plateau phase maintained by calcium influx through L-type channels?
A) Phase 0
B) Phase 1
C) Phase 2
D) Phase 3
Answer: C