Question

Which of the following statements is CORRECT?

• A. Mitral valve has three cusps which prevent the backflow of blood.
• B. Thebesian valve guards the opening of inferior vena cava to the right atrium
• C. Valves are absent between pulmonary veins and left atrium
• D. The opening of the superior vena cava into the right atrium is guarded by the Eustachian valve.

Answer 1

The correct option is C Valves are absent between pulmonary veins and left atrium

The pulmonary veins carry the oxygenated blood from the lungs to the left atrium. They do not have valves because the pressure exerted by the heart is strong enough to keep the blood flowing in one direction.

The thebesian valve guards the opening of the coronary sinus into the right atrium to prevent the backflow of blood. Coronary sinus collects the deoxygenated blood from heart muscles and drains them into the right atrium.

The opening of the inferior vena cava (IVC) to the right atrium is guarded by a Eustachian valve. IVC collects deoxygenated blood from the lower body parts.

Mitral valve is a bicuspid valve which consists of 2 cusps that prevent the backflow of blood from the left ventricle to the left auricle. Three cusps are present in the tricuspid valve that is present between the right atrium and right ventricle.

The superior vena cava (SVC) collects the deoxygenated blood from upper body parts and drains them into the right atrium. The opening of the SVC into the right atrium is not guarded by any valves.