A 28-year-old woman in casualty has palpitations, a regular narrow-complex tachycardia of 180/min and normal blood pressure. Massage over the right carotid sinus ends the tachycardia. How did the manoeuvre work?

Raised vagal tone slowing AV node conduction

Reduced firing of the carotid sinus receptors

Stimulation of the carotid body chemoreceptors

Increased sympathetic tone to the SA node

A 40-year-old man from coastal Odisha has had progressive swelling of his left leg for eight years after recurrent bouts of fever with painful groin nodes. The swelling is firm, non-pitting, and the skin is thickened. Night blood smear shows microfilariae. Which Starling-force change mainly explains this oedema?

Filtered protein is not cleared, raising interstitial oncotic pressure

Capillary hydrostatic pressure is raised by venous obstruction

Plasma oncotic pressure is reduced by low albumin

Capillary permeability is raised by histamine release

A 64-year-old woman with severe knee osteoarthritis cannot exercise, so she has a myocardial perfusion scan with IV adenosine. The scan shows reduced uptake in the anterior wall, and angiography later shows an 80% LAD stenosis. Why does adenosine reveal the stenosis?

Only normal arterioles have dilator reserve

Adenosine slows the heart and shortens diastolic perfusion

Adenosine raises myocardial oxygen demand like exercise

Adenosine constricts the stenosed artery at the plaque

Haemodynamics, blood pressure regulation and shock

18 NEET-PG practice questions on Haemodynamics, blood pressure regulation and shock, part of Physiology. The first 18 are below; the first 5 with answers and explanations (tap Show answer after you have chosen), the rest in Learn with a free account.

Question 1 · Medium
A 28-year-old woman in casualty has palpitations, a regular narrow-complex tachycardia of 180/min and normal blood pressure. Massage over the right carotid sinus ends the tachycardia. How did the manoeuvre work?
1. AReduced firing of the carotid sinus receptors
2. BRaised vagal tone slowing AV node conduction
3. CStimulation of the carotid body chemoreceptors
4. DIncreased sympathetic tone to the SA node
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Answer: B · Raised vagal tone slowing AV node conduction
Pressure on the carotid sinus stretches its baroreceptors, which the brain reads as a rise in blood pressure. Impulses travel in the sinus nerve of the glossopharyngeal to the nucleus tractus solitarius, which increases vagal outflow and reduces sympathetic outflow. Vagal stimulation slows conduction through the AV node and can break a re-entrant circuit that uses it, as in most supraventricular tachycardias. Carotid massage is avoided in older patients with carotid bruits because it can dislodge plaque.
- A: Massage stretches the baroreceptors and increases their firing.
- C: The carotid body senses PO2, PCO2 and pH, and is not activated by pressure.
- D: The reflex reduces sympathetic tone; more sympathetic drive would speed the heart.
Question 2 · Medium
A 52-year-old man with diabetes is admitted from the surgical OPD with spreading cellulitis of the foot. He is febrile at 39.4 °C, BP 80/42 mmHg after 2 L of fluid, pulse 124/min, and his hands are warm and flushed. A pulmonary artery catheter shows cardiac output 8.4 L/min, low systemic vascular resistance and wedge pressure 9 mmHg. What type of shock does he have?
1. ACardiogenic shock
2. BHypovolaemic shock
3. CObstructive shock
4. DDistributive shock
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Answer: D · Distributive shock
High cardiac output with low systemic vascular resistance, a normal wedge pressure and warm peripheries is the early distributive picture of septic shock. Inflammatory mediators and nitric oxide dilate arterioles and the heart compensates by pumping more, yet tissue perfusion fails because flow is maldistributed and cells cannot use oxygen well. Management is source control, early antibiotics, fluids and norepinephrine to restore vascular tone. Late sepsis can depress the myocardium and lower cardiac output.
- A: Cardiogenic shock has a low cardiac output, high wedge pressure and cold peripheries.
- B: Hypovolaemic shock has a low cardiac output, low filling pressures and high resistance.
- C: Obstructive shock (tamponade, massive PE) has a low cardiac output with high resistance.
Question 3 · Medium
A healthy 20-year-old medical student volunteers for a tilt-table test in the physiology lab. Consider four statements about the first minute after he is tilted from supine to upright: 1. Venous return and stroke volume fall. 2. Firing of the carotid sinus baroreceptors decreases. 3. Vagal tone to the heart increases. 4. Arteriolar constriction increases in the splanchnic bed and limbs. Which statements are correct?
1. A1, 3 and 4 only
2. B1, 2 and 4 only
3. C1 and 4 only
4. D1 and 2 only
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Answer: B · 1, 2 and 4 only
Statements 1, 2 and 4 are correct. On standing, several hundred millilitres of blood pool in the leg veins, so venous return, stroke volume and arterial pressure fall and the baroreceptors fire less. The reflex response is less vagal and more sympathetic outflow: heart rate rises and arterioles and veins constrict, so pressure is restored within seconds. Statement 3 is wrong: vagal tone decreases, which is why the pulse quickens on standing.
- A: Includes increased vagal tone and omits the fall in baroreceptor firing.
- C: Omits the fall in baroreceptor firing that triggers the reflex.
- D: Omits the reflex arteriolar constriction that restores pressure.
Question 4 · Medium
A 40-year-old man from coastal Odisha has had progressive swelling of his left leg for eight years after recurrent bouts of fever with painful groin nodes. The swelling is firm, non-pitting, and the skin is thickened. Night blood smear shows microfilariae. Which Starling-force change mainly explains this oedema?
1. ACapillary hydrostatic pressure is raised by venous obstruction
2. BFiltered protein is not cleared, raising interstitial oncotic pressure
3. CPlasma oncotic pressure is reduced by low albumin
4. DCapillary permeability is raised by histamine release
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Answer: B · Filtered protein is not cleared, raising interstitial oncotic pressure
Adult Wuchereria bancrofti in the lymphatics obstructs lymph drainage. Lymph normally returns the small amount of protein that leaks from capillaries; when it cannot, protein accumulates in the interstitium, raising interstitial oncotic pressure and holding fluid outside the capillaries. The protein-rich fluid provokes fibrosis, so the oedema becomes firm and non-pitting, unlike the pitting oedema of heart failure or hypoalbuminaemia. Mass drug administration with DEC and albendazole under the national filaria programme aims to stop transmission.
- A: Venous obstruction causes soft pitting oedema with low-protein fluid.
- C: Hypoalbuminaemia causes generalised soft pitting oedema, not one firm limb.
- D: Histamine-mediated leak is acute and transient, as in urticaria or anaphylaxis.
Question 5 · Medium
A 64-year-old woman with severe knee osteoarthritis cannot exercise, so she has a myocardial perfusion scan with IV adenosine. The scan shows reduced uptake in the anterior wall, and angiography later shows an 80% LAD stenosis. Why does adenosine reveal the stenosis?
1. AAdenosine slows the heart and shortens diastolic perfusion
2. BAdenosine raises myocardial oxygen demand like exercise
3. COnly normal arterioles have dilator reserve
4. DAdenosine constricts the stenosed artery at the plaque
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Answer: C · Only normal arterioles have dilator reserve
Adenosine is a key metabolic coronary vasodilator: arterioles beyond a significant stenosis are already dilated at rest to keep flow normal, so they have no reserve. When adenosine dilates the normal beds, flow rises sharply there but not beyond the stenosis, and the tracer shows a relative defect (with some steal of flow). The test therefore measures coronary flow reserve without exercise. Theophylline and caffeine block adenosine receptors, so they are stopped before the test.
- A: Slowing of the heart would lengthen, not shorten, diastole.
- B: Adenosine does not mimic exercise by raising demand; dobutamine does.
- D: Adenosine dilates coronary arterioles; it does not constrict the plaque segment.
Question 6 · Medium
A 46-year-old woman undergoes right heart catheterisation for unexplained breathlessness. Her oxygen consumption is 250 mL/min, arterial oxygen content 20 mL/dL and mixed venous (pulmonary artery) oxygen content 15 mL/dL. What is her cardiac output by the Fick principle?
1. A5 L/min
2. B1.25 L/min
3. C0.5 L/min
4. D50 L/min
Answer and explanation in LearnFree account
Question 7 · Medium
A 35-year-old man who fell from a scaffold is in the neurosurgery ward with an acute subdural haematoma. Over an hour his GCS falls from 12 to 7, BP rises from 130/80 to 196/104 mmHg, pulse falls from 88 to 52/min and breathing becomes irregular. What explains the change in his blood pressure?
1. ALoss of baroreceptor input from the carotid sinus
2. BFluid overload from intravenous saline in the ward
3. CBrainstem ischaemia driving sympathetic outflow
4. DPain-induced catecholamine release from the scalp wound
Answer and explanation in LearnFree account
Question 8 · Hard
A 30-year-old woman at 36 weeks with severe pre-eclampsia is being studied for the mechanism of her pulmonary oedema. Estimated values at the pulmonary capillary are: capillary hydrostatic pressure 22 mmHg, interstitial hydrostatic pressure -4 mmHg, plasma oncotic pressure 19 mmHg and interstitial oncotic pressure 11 mmHg. What is the net filtration pressure, and in which direction?
1. A10 mmHg, out of the capillary
2. B4 mmHg, into the capillary
3. C18 mmHg, out of the capillary
4. D26 mmHg, out of the capillary
Answer and explanation in LearnFree account
Question 9 · Medium
A 22-year-old man is brought to casualty after a highway crash with a closed femur fracture. He is pale, cold and sweaty, pulse 118/min, BP 104/80 mmHg. About 1 litre of blood is estimated in the thigh. What is the main mechanism that keeps his blood pressure near normal at this stage?
1. AAldosterone retaining sodium and water within minutes
2. BRaised baroreceptor firing increases vagal outflow
3. CReduced baroreceptor firing raises sympathetic outflow
4. DCentral ischaemic response to cerebral hypoxia
Answer and explanation in LearnFree account
Question 10 · Medium
A 59-year-old bidi smoker complains of calf pain on walking 200 metres. Angiography shows a segment of his superficial femoral artery whose internal radius is reduced to half the normal. If the pressure gradient and blood viscosity stay the same, how does flow through this segment change?
1. AFalls to one-sixteenth
2. BFalls to one-quarter
3. CFalls to one-eighth
4. DFalls to one-half
Answer and explanation in LearnFree account
Question 11 · Medium
A 27-year-old woman has BP 178/112 mmHg on three visits to the medicine OPD. Her potassium is 3.2 mmol/L, and Doppler shows a beaded narrowing of the right renal artery suggesting fibromuscular dysplasia. Which mechanism mainly sustains her hypertension?
1. ARenin release from the underperfused kidney
2. BLoss of pressure natriuresis in the normal kidney
3. CExcess catecholamines from an adrenal tumour
4. DPrimary excess of aldosterone from the adrenal
Answer and explanation in LearnFree account
Question 12 · Easy
A 24-year-old man with a severe head injury after a two-wheeler crash is in the neurosurgery ICU with raised intracranial pressure. The intensivist briefly increases his ventilator rate to lower the PaCO2 to about 32 mmHg while mannitol is arranged. How does this lower intracranial pressure?
1. AAn osmotic shift of water out of brain tissue
2. BReduced CSF production by the choroid plexus
3. CCerebral vasoconstriction cuts blood volume
4. DBetter oxygenation dilates cerebral vessels
Answer and explanation in LearnFree account
Question 13 · Easy
During a carotid endarterectomy at a district hospital, the anaesthetist notes sudden bradycardia and a fall in blood pressure each time the surgeon handles the carotid bifurcation. In which nerve does the afferent limb of this reflex travel?
1. AHypoglossal nerve
2. BCervical sympathetic chain
3. CGlossopharyngeal nerve
4. DVagus nerve
Answer and explanation in LearnFree account
Question 14 · Medium
A 61-year-old man in the CCU has an acute inferior wall myocardial infarction with ST elevation in V4R. He is hypotensive with raised jugular venous pressure and clear lung fields. Which haemodynamic profile is expected on right heart catheterisation?
1. AHigh right atrial, normal wedge pressure, low output
2. BLow right atrial, low wedge pressure, low output
3. CHigh right atrial, high wedge pressure, high output
4. DNormal right atrial, high wedge pressure, low output
Answer and explanation in LearnFree account
Question 15 · Medium
A 55-year-old man with long-standing diabetes faints when he stands up. In the autonomic function lab he performs a Valsalva manoeuvre: his blood pressure falls steadily during the strain with no rise in heart rate, and there is no overshoot of pressure after release. What do these findings indicate?
1. AFailure of the baroreflex autonomic efferents
2. BHeart failure with a square-wave response
3. CA normal response to a forceful strain
4. DHypovolaemia from osmotic diuresis
Answer and explanation in LearnFree account
Question 16 · Easy
A 58-year-old man with known coronary artery disease develops atrial fibrillation with a ventricular rate of 160/min and gets chest pain in the emergency ward. His blood pressure is maintained. Why does the fast heart rate reduce blood flow to his left ventricular myocardium?
1. ADiastole, when the left ventricle is perfused, is shortened
2. BVagal tone constricts the epicardial coronary arteries
3. CMyocardial oxygen extraction falls at high heart rates
4. DAortic pressure falls in systole when the ventricle is perfused
Answer and explanation in LearnFree account
Question 17 · Hard
A 26-year-old construction worker falls from a height and has a complete spinal cord injury at T2. In casualty his BP is 78/40 mmHg, pulse 48/min, his skin is warm and dry, and FAST scan and chest X-ray show no bleeding. Below the injury there is flaccid paralysis with absent reflexes. What best explains his hypotension?
1. ASpinal shock from loss of spinal cord reflexes
2. BCardiogenic shock from myocardial contusion
3. CHypovolaemic shock from occult internal bleeding
4. DNeurogenic shock from loss of sympathetic outflow
Answer and explanation in LearnFree account
Question 18 · Hard
A 68-year-old man with untreated hypertension for many years comes to casualty with headache and BP 224/128 mmHg but no focal deficit. The intern gives drugs that bring the pressure to 118/76 mmHg within 40 minutes, after which he becomes confused and develops a left hemiparesis. What explains this deterioration?
1. ASudden fall in pressure triggers the Cushing reflex
2. BCerebral vessels lose their response to arterial PCO2
3. CAutoregulation curve shifted to higher pressures
4. DChronic hypertension makes cerebral vessels unable to constrict
Answer and explanation in LearnFree account

Haemodynamics, blood pressure regulation and shock

A 28-year-old woman in casualty has palpitations, a regular narrow-complex tachycardia of 180/min and normal blood pressure. Massage over the right carotid sinus ends the tachycardia. How did the manoeuvre work?

A 64-year-old woman with severe knee osteoarthritis cannot exercise, so she has a myocardial perfusion scan with IV adenosine. The scan shows reduced uptake in the anterior wall, and angiography later shows an 80% LAD stenosis. Why does adenosine reveal the stenosis?

A 46-year-old woman undergoes right heart catheterisation for unexplained breathlessness. Her oxygen consumption is 250 mL/min, arterial oxygen content 20 mL/dL and mixed venous (pulmonary artery) oxygen content 15 mL/dL. What is her cardiac output by the Fick principle?

A 35-year-old man who fell from a scaffold is in the neurosurgery ward with an acute subdural haematoma. Over an hour his GCS falls from 12 to 7, BP rises from 130/80 to 196/104 mmHg, pulse falls from 88 to 52/min and breathing becomes irregular. What explains the change in his blood pressure?

A 22-year-old man is brought to casualty after a highway crash with a closed femur fracture. He is pale, cold and sweaty, pulse 118/min, BP 104/80 mmHg. About 1 litre of blood is estimated in the thigh. What is the main mechanism that keeps his blood pressure near normal at this stage?

A 59-year-old bidi smoker complains of calf pain on walking 200 metres. Angiography shows a segment of his superficial femoral artery whose internal radius is reduced to half the normal. If the pressure gradient and blood viscosity stay the same, how does flow through this segment change?

A 27-year-old woman has BP 178/112 mmHg on three visits to the medicine OPD. Her potassium is 3.2 mmol/L, and Doppler shows a beaded narrowing of the right renal artery suggesting fibromuscular dysplasia. Which mechanism mainly sustains her hypertension?

A 24-year-old man with a severe head injury after a two-wheeler crash is in the neurosurgery ICU with raised intracranial pressure. The intensivist briefly increases his ventilator rate to lower the PaCO2 to about 32 mmHg while mannitol is arranged. How does this lower intracranial pressure?

During a carotid endarterectomy at a district hospital, the anaesthetist notes sudden bradycardia and a fall in blood pressure each time the surgeon handles the carotid bifurcation. In which nerve does the afferent limb of this reflex travel?

A 61-year-old man in the CCU has an acute inferior wall myocardial infarction with ST elevation in V4R. He is hypotensive with raised jugular venous pressure and clear lung fields. Which haemodynamic profile is expected on right heart catheterisation?

A 58-year-old man with known coronary artery disease develops atrial fibrillation with a ventricular rate of 160/min and gets chest pain in the emergency ward. His blood pressure is maintained. Why does the fast heart rate reduce blood flow to his left ventricular myocardium?