Question

Which of the following statements is correct about valves?

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

Answer 1

The correct option is A

Valves are absent between pulmonary veins and left atrium

The correct option is A.

Explanation for the correct option:

Option A:

1. Blood can only flow one way via the heart's valves, which resemble flap-like structures.
2. The valves in the heart open and close as it contracts, controlling how much blood flows through the structure.
3. The opening and closing of the valves are controlled by pressure fluctuations produced inside the heart as well as by some internal cardiac muscles.
4. Heart valves come in two main varieties: atrioventricular and semilunar.
5. The two atrioventricular (AV) valves, which are situated between the atria and the ventricles, are the tricuspid and mitral valves.
6. The two semilunar (SL) valves found in the arteries that leave the heart are the aortic valve and the pulmonary valve.
7. There are therefore four valves altogether.

Explanations for the incorrect options:

Option B:

1. The thebesian valve guards the coronary sinus' entry into the right atrium to stop blood from flowing backwards.
2. Deoxygenated blood from the cardiac muscles is collected by the coronary sinus and drained into the right atrium.

Option C:

1. The bicuspid mitral valve, which has two cusps, stops blood from flowing backwards from the left ventricle to the left atrium.
2. The tricuspid valve, which is located between the right atrium and right ventricle, has three cusps.

Option D:

1. Deoxygenated blood from higher body parts is collected by the superior vena cava (SVC) and drained into the right atrium.
2. There are no valves to protect the SVC's entry into the right atrium.

Final answer: The correct statement about valves is valves are absent between pulmonary veins and the left atrium.