Question

Post caval opening in right auricle is guarded by:

A. Atrio-ventricular valve

B. Tricuspid valve

C. Bicuspid valve

D. Eustachian valve

Answer 1

Hint:

The heart consists of four chambers, two atria and two ventricles. There is a valve through which blood passes before leaving each chamber of the heart. The valves prevent the backward flow of blood during the transportation to lungs and the whole body.

Complete answer:

These valves are actual flaps that are located on each end of the two ventricles (lower chambers of the heart). They act as one way inlets of blood on one side of a ventricle and one way outlets of blood on the other side of a ventricle. Normal valves have three flaps, except the mitral valve, which has two flaps. The four heart valves include the following:

> Tricuspid valve or atrio-ventricular valve: It is located between the right atrium and the right ventricle. It has three cusps and prevents the backflow of the blood from the right ventricle to the right atrium.

> Pulmonary valve: It is also called as the semilunar valve of the heart that lies between the right ventricle and the pulmonary artery. It also has three cusps.

> Mitral valve: It has two cusps and is located between the left atrium and left ventricle. It opens to allow the blood to be pumped from lungs to the left atrium.

> Aortic valve: It is located between the left ventricle and the aorta possessing three cusps unless it is abnormal from birth i.e. bicuspid .It allows the blood to flow through the left ventricle and leads it to the whole body through the aorta.

Further, the Eustachian valve or the valve of inferior vena cava is a venous valve (valve of a vein) which lies at the junction of inferior vena cava and right atrium. The opening of the vena cava is guarded by an Eustachian valve which allows the blood to enter in the right atrium. It helps to direct the flow of oxygen-rich blood through the right atrium into the left atrium and away from the right ventricle. The vena cava (superior and inferior vena cava) brings the deoxygenated blood from the body

The correct answer is option D. 

Note:
The Eustachian valve is an embryological remnant (a part that is left after the greater part has been used) of the inferior vena cava valve. It is usually absent or inconspicuous (a part that is not clearly visible) and has no known function in a normal adult.