Body Fluids and Circulation – Circulatory Pathways: NEET MCQs with Answers

15 free questions on Body Fluids and Circulation – Circulatory Pathways for NEET (UG), starting with previous-year NEET and AIPMT questions. Try each one, then tap Show answer for the answer and a short explanation.

Syllabus covered: Circulatory Pathways: Human circulatory system-Structure of human heart and blood vessels; Cardiac cycle, cardiac output, ECG,

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Question 1

Previous-year question
What does the P-wave of a standard ECG represent? [NEET (Sawaimadhopur) 2024]
  1. Repolarisation of the ventricles
  2. Depolarisation of the ventricles
  3. End of systole
  4. Depolarisation of the atria
Show answer
Answer: (D) Depolarisation of the atria
Explanation: The P-wave represents the electrical excitation (depolarisation) of the atria, which leads to atrial contraction. Ventricular depolarisation is shown by the QRS complex, ventricular repolarisation by the T-wave, and the end of the T-wave marks the end of systole.

Question 2

Previous-year question
Match the structures of the heart in List I with their descriptions in List II and choose the correct answer. [NEET (Sawaimadhopur) 2024]
List I:
A. Tricuspid valves
B. Sino-atrial node
C. Mitral valves
D. Semilunar valves
List II:
I. Guards the opening between right atrium and right ventricle
II. Guards the opening between the left atrium and the left ventricle
III. Guards the openings of right and left ventricles into pulmonary artery and aorta, respectively
IV. Cardiac musculature in the right upper corner of right atrium
  1. A-II, B-I, C-IV, D-III
  2. A-III, B-IV, C-I, D-II
  3. A-I, B-IV, C-II, D-III
  4. A-III, B-IV, C-II, D-I
Show answer
Answer: (C) A-I, B-IV, C-II, D-III
Explanation: Tricuspid valves guard the opening between the right atrium and right ventricle (A-I); the SA node is a patch of nodal musculature in the right upper corner of the right atrium (B-IV); mitral (bicuspid) valves guard the left atrio-ventricular opening (C-II); and semilunar valves guard the openings of the right and left ventricles into the pulmonary artery and aorta respectively (D-III).

Question 3

Previous-year question
Match the ECG components in List I with the electrical activity of the heart in List II and choose the correct answer. [NEET (Manipur) 2023]
List I (ECG):
(A) P-wave
(B) QRS complex
(C) T-wave
(D) End of T-wave
List II (Electrical activity of heart):
(I) Depolarisation of ventricles
(II) End of systole
(III) Depolarisation of atria
(IV) Repolarisation of ventricles
  1. A-(IV), B-(I), C-(III), D-(II)
  2. A-(I), B-(IV), C-(III), D-(II)
  3. A-(IV), B-(III), C-(I), D-(II)
  4. A-(III), B-(I), C-(IV), D-(II)
Show answer
Answer: (D) A-(III), B-(I), C-(IV), D-(II)
Explanation: The P-wave represents depolarisation of the atria (A-III), the QRS complex depolarisation of the ventricles (B-I), and the T-wave repolarisation of the ventricles (C-IV). The end of the T-wave marks the end of systole (D-II).

Question 4

Previous-year question
Identify the correct statement from the following. [NEET 2022]
  1. The tricuspid and bicuspid valves open due to the pressure exerted by the simultaneous contraction of the atria.
  2. Blood moves freely from the atria to the ventricles during joint diastole.
  3. Increased ventricular pressure causes the semilunar valves to close.
  4. The atrio-ventricular node (AVN) generates an action potential to stimulate atrial contraction.
Show answer
Answer: (B) Blood moves freely from the atria to the ventricles during joint diastole.
Explanation: During joint diastole the tricuspid and bicuspid valves are open, so blood flows freely from the atria into the ventricles. The AV valves open when ventricular pressure falls below atrial pressure, semilunar valves close when ventricular pressure falls (not rises), and atrial contraction is stimulated by the SA node, not the AVN.

Question 5

Previous-year question
Every component of the nodal tissue is capable of generating action potentials on its own. Why, then, does the SA node serve as the normal pacemaker of the heart? [NEET (Odisha) 2019]
  1. The SA node has the lowest rate of depolarisation.
  2. The SA node is the only component that can generate the threshold potential.
  3. Only the SA node can transmit the action potential to the other components.
  4. The SA node has the highest rate of depolarisation.
Show answer
Answer: (D) The SA node has the highest rate of depolarisation.
Explanation: The SA node can generate the maximum number of action potentials (70–75 per minute), i.e. it has the highest rate of depolarisation, so it initiates and sets the rhythm of contraction. Other nodal tissues can also reach threshold and conduct impulses, but at slower rates, so they are overridden.

Question 6

Previous-year question
The tricuspid valve is found in between the [AIPMT 1989]
  1. sinus venosus and right auricle
  2. right auricle and right ventricle
  3. left ventricle and left auricle
  4. ventricle and aorta
Show answer
Answer: (B) right auricle and right ventricle
Explanation: The right auricle opens into the right ventricle through a wide circular right auriculo-ventricular aperture guarded by a valve formed of three flaps called cusps — hence the name tricuspid valve. It ensures the unidirectional flow of blood from right auricle to right ventricle.

Question 7

Previous-year question
A vein possesses a large lumen because [AIPMT 1990]
  1. tunica media and tunica externa form a single coat
  2. tunica interna and tunica media form a single coat
  3. tunica interna, tunica media and tunica externa are thin
  4. tunica media is a thin coat
Show answer
Answer: (D) tunica media is a thin coat
Explanation: Every artery and vein consists of three layers: an inner lining of squamous endothelium (tunica interna), a middle layer of smooth muscle and elastic fibre (tunica media), and an outer layer of fibrous connective tissue with collagen fibres (tunica externa). In veins the tunica media is comparatively thin, which is what gives them a large lumen.
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Question 8

Previous-year question
The splenic artery arises from the [AIPMT 1990]
  1. anterior mesenteric artery
  2. coeliac artery
  3. posterior mesenteric artery
  4. intestinal artery
Show answer
Answer: (B) coeliac artery
Explanation: The splenic artery is the blood vessel that supplies oxygenated blood to the spleen. It branches from the coeliac (celiac) artery and follows a course superior to the pancreas.

Question 9

Previous-year question
The 'dup' sound is produced during the closure of the [AIPMT 1994]
  1. semilunar valves
  2. bicuspid valve
  3. tricuspid valve
  4. both bicuspid and tricuspid valves
Show answer
Answer: (A) semilunar valves
Explanation: Closure of the atrio-ventricular valves at the start of ventricular systole produces the first heart sound, 'lubb'. Rapid closure of the semilunar valves at the beginning of ventricular diastole produces the second sound, 'dup'.

Question 10

Previous-year question
The correct route through which the pulse-making impulse travels in the heart is [AIPMT 1995]
  1. AV node → Bundle of His → SA node → Purkinje fibres → Heart muscles
  2. AV node → SA node → Purkinje fibres → Bundle of His → Heart muscles
  3. SA node → Purkinje fibres → Bundle of His → AV node → Heart muscles
  4. SA node → AV node → Bundle of His → Purkinje fibres → Heart muscles
Show answer
Answer: (D) SA node → AV node → Bundle of His → Purkinje fibres → Heart muscles
Explanation: The correct route is SA node → AV node → Bundle of His → Purkinje fibres → Heart muscles. The impulse originates at the pacemaker and is conducted through the nodal and conducting tissue to the ventricular musculature.

Question 11

Previous-year question
The thickening of the walls of arteries is called [AIPMT 1999]
  1. arthritis
  2. atherosclerosis
  3. anaeurysm
  4. both arthritis and anaeurysm
Show answer
Answer: (B) atherosclerosis
Explanation: Atherosclerosis involves thickening of the inner walls of the arteries due to the deposition of lipid (cholesterol), which prevents the arteries from dilating properly and restricts blood flow.

Question 12

Previous-year question
The pulmonary artery is different from the pulmonary vein because it has [AIPMT 2000]
  1. a larger lumen
  2. thick muscular walls
  3. no endothelium
  4. valves
Show answer
Answer: (B) thick muscular walls
Explanation: Arteries have thick muscular walls and a narrow lumen, and they possess no valves. Endothelium is present in both arteries and veins, while a large lumen and valves are features of veins.

Question 13

Previous-year question
The bundle of His is a network of [AIPMT 2003]
  1. nerve fibres distributed in ventricles
  2. nerve fibres found throughout the heart
  3. muscle fibres distributed throughout the heart walls
  4. muscle fibres found only in the ventricle wall
Show answer
Answer: (D) muscle fibres found only in the ventricle wall
Explanation: The bundle of His is a network of specialised conducting muscle fibres (continuing as the Purkinje fibres) which transmit the impulse from the AV node to all parts of both ventricles. It is therefore confined to the ventricular wall, and it is muscular rather than nervous in nature.

Question 14

Previous-year question
The systemic heart refers to [AIPMT 2003]
  1. the entire heart in lower vertebrates
  2. the two ventricles together in humans
  3. the heart that contracts under stimulation from the nervous system
  4. the left auricle and left ventricle in higher vertebrates
Show answer
Answer: (D) the left auricle and left ventricle in higher vertebrates
Explanation: The systemic heart refers to the left auricle and left ventricle in higher vertebrates. This left side of the heart drives the systemic circulation, distributing oxygenated blood to the body.

Question 15

Previous-year question
The pacemaker of the heart is the [AIPMT 2004, 2002, 1999, 1994]
  1. AV node
  2. bundle of His
  3. SA node
  4. Purkinje fibres
Show answer
Answer: (C) SA node
Explanation: The SA node lies in the right wall of the right auricle just below the opening of the superior vena cava. Because it is the first to originate the cardiac impulse and determines the rate of the heartbeat, it is called the pacemaker.

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