King Edward Medical University Entry Test Biology Circulation — Set 3

Circulation MCQs set 3 for King Edward Medical University Entry Test Biology — 20 solved questions.

King Edward Medical University Entry Test Biology Circulation — Set 3

  1. Question 1

    Q1. In a patient with a patent ductus arteriosus, which vessel is responsible for shunting blood from the aorta to the pulmonary artery?

    • A) Pulmonary vein
    • B) Ductus arteriosus
    • C) Pulmonary artery
    • D) Aortic arch

    Answer: Ductus arteriosus

    Explanation: Ductus arteriosus shunts blood from aorta to pulmonary artery when patent; pulmonary vein is not directly involved.

  2. Question 2

    Q2. Which structure is NOT a part of the conducting system of the heart?

    • A) SA node
    • B) AV node
    • C) Bundle of His
    • D) Purkinje fibers of ventricular myocardium

    Answer: Purkinje fibers of ventricular myocardium

    Explanation: Purkinje fibers are part of the conducting system but the ventricular myocardium itself is not; it's the end pathway.

  3. Question 3

    Q3. A person has a condition where the blood flows from the right atrium directly into the left atrium. Which congenital defect is most likely?

    • A) Atrial septal defect
    • B) Ventricular septal defect
    • C) Tetralogy of Fallot
    • D) Patent foramen ovale

    Answer: Atrial septal defect

    Explanation: Atrial septal defect allows blood to flow between atria; patent foramen ovale is a related but distinct condition.

  4. Question 4

    Q4. The hepatic portal vein is formed by the confluence of which two veins?

    • A) Superior mesenteric and splenic veins
    • B) Inferior mesenteric and splenic veins
    • C) Superior and inferior mesenteric veins
    • D) Hepatic and splenic veins

    Answer: Superior mesenteric and splenic veins

    Explanation: Hepatic portal vein is formed by superior mesenteric and splenic veins; inferior mesenteric drains into splenic.

  5. Question 5

    Q5. In the hepatic sinusoids, which type of cell is responsible for phagocytosis?

    • A) Kupffer cells
    • B) Hepatocytes
    • C) Stellate cells
    • D) Endothelial cells

    Answer: Kupffer cells

    Explanation: Kupffer cells are macrophages in hepatic sinusoids; hepatocytes are involved in metabolism, not phagocytosis.

  6. Question 6

    Q6. Cardiac output is determined by which two factors?

    • A) Heart rate and stroke volume
    • B) Heart rate and blood pressure
    • C) Stroke volume and peripheral resistance
    • D) Blood pressure and peripheral resistance

    Answer: Heart rate and stroke volume

    Explanation: Cardiac output equals heart rate times stroke volume; blood pressure is a result, not a determinant.

  7. Question 7

    Q7. The lymphatic system is characterized by which unique feature?

    • A) Presence of valves
    • B) Absence of blood capillaries
    • C) Presence of closed-ended lymphatic capillaries
    • D) Absence of smooth muscle

    Answer: Presence of closed-ended lymphatic capillaries

    Explanation: Lymphatic capillaries are closed-ended, allowing interstitial fluid entry; valves are present in larger lymphatics.

  8. Question 8

    Q8. Which vessel has the highest oxygen content in a normal adult?

    • A) Pulmonary artery
    • B) Pulmonary vein
    • C) Aorta
    • D) Coronary sinus

    Answer: Pulmonary vein

    Explanation: Pulmonary veins carry oxygenated blood from lungs to left atrium; aorta also carries oxygenated blood.

  9. Question 9

    Q9. In a capillary, the rate of fluid filtration is determined by which factor?

    • A) Capillary hydrostatic pressure
    • B) Interstitial fluid hydrostatic pressure
    • C) Capillary oncotic pressure
    • D) All of the above pressures

    Answer: All of the above pressures

    Explanation: Fluid filtration is determined by balance of hydrostatic and oncotic pressures across capillary wall.

  10. Question 10

    Q10. The coronary circulation receives its blood supply during which phase of the cardiac cycle?

    • A) Systole
    • B) Diastole
    • C) Both systole and diastole equally
    • D) Isovolumetric contraction

    Answer: Diastole

    Explanation: Coronary circulation occurs mainly during diastole due to ventricular compression during systole.

  11. Question 11

    Q11. Which of the following is a characteristic of the blood-brain barrier?

    • A) Presence of fenestrated capillaries
    • B) Tight junctions between endothelial cells
    • C) Absence of pericytes
    • D) Lack of basement membrane

    Answer: Tight junctions between endothelial cells

    Explanation: Tight junctions between endothelial cells restrict passage across blood-brain barrier; fenestrated capillaries are elsewhere.

  12. Question 12

    Q12. The foramen ovale is a shunt that allows blood to bypass which chamber in the fetal heart?

    • A) Right atrium
    • B) Left atrium
    • C) Right ventricle
    • D) Lungs

    Answer: Lungs

    Explanation: Foramen ovale allows blood to bypass lungs by shunting from right to left atrium in fetal circulation.

  13. Question 13

    Q13. Which condition is associated with an abnormal connection between the aorta and the pulmonary artery?

    • A) Atrial septal defect
    • B) Ventricular septal defect
    • C) Patent ductus arteriosus
    • D) Tetralogy of Fallot

    Answer: Patent ductus arteriosus

    Explanation: Patent ductus arteriosus is an abnormal connection between aorta and pulmonary artery.

  14. Question 14

    Q14. The pressure in the left ventricle is highest during which phase?

    • A) Isovolumetric contraction
    • B) Ventricular ejection
    • C) Isovolumetric relaxation
    • D) Rapid filling

    Answer: Ventricular ejection

    Explanation: Left ventricular pressure peaks during ventricular ejection; isovolumetric contraction precedes ejection.

  15. Question 15

    Q15. Which factor increases venous return to the heart?

    • A) Increased peripheral resistance
    • B) Decreased blood volume
    • C) Muscle contraction
    • D) Standing still for long periods

    Answer: Muscle contraction

    Explanation: Muscle contraction compresses veins and increases venous return; standing still decreases return.

  16. Question 16

    Q16. Which part of the cardiac conduction system is responsible for the delay between atrial and ventricular contraction?

    • A) SA node
    • B) AV node
    • C) Bundle of His
    • D) Purkinje fibers

    Answer: AV node

    Explanation: AV node delays impulse to allow atrial contraction before ventricular contraction.

  17. Question 17

    Q17. In which condition does the aorta arise from the right ventricle?

    • A) Tetralogy of Fallot
    • B) Transposition of the great arteries
    • C) Truncus arteriosus
    • D) Double outlet right ventricle

    Answer: Transposition of the great arteries

    Explanation: Transposition of great arteries involves aorta arising from right ventricle and pulmonary artery from left.

  18. Question 18

    Q18. The hepatic artery and the hepatic portal vein supply blood to which organ?

    • A) Liver
    • B) Spleen
    • C) Kidney
    • D) Pancreas

    Answer: Liver

    Explanation: Hepatic artery and portal vein supply liver; hepatic artery brings oxygenated blood, portal vein brings nutrient-rich blood.

  19. Question 19

    Q19. In the human heart, which structure separates the right atrium from the right ventricle?

    • A) Tricuspid valve
    • B) Pulmonary valve
    • C) Mitral valve
    • D) Aortic valve

    Answer: Tricuspid valve

    Explanation: Tricuspid valve separates right atrium from right ventricle; Mitral valve does the same for left side.

  20. Question 20

    Q20. A patient's ECG shows a prolonged PR interval. Which process is being delayed?

    • A) Atrial depolarization
    • B) Ventricular depolarization
    • C) AV node conduction
    • D) SA node firing

    Answer: AV node conduction

    Explanation: PR interval represents time from SA node firing to ventricular depolarization; delay occurs in AV node.

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In a patient with a patent ductus arteriosus, which vessel is responsible for shunting blood from the aorta to the pulmonary artery?