Question

The sino-auricular valve occurs
A. In the sinus venosus
B. In the edges of sino- auricular aperture
C. In the truncus- arteriosus
D. At the auriculo-ventricular aperture

Answer 1

Hint: The heart valves help in keeping the blood flowing in the right direction. There are many valves in the mammalian heart, which helps in the proper directional blood circulation, it prevents the backflow of blood. The auricles of the atria are the two upper chambers of the heart, the blood from these chambers flow to the ventricles.

Complete answer: The sino auricular aperture is a large aperture, which is present on the right auricle or right atria, which is the upper right chamber of the human heart. This passage is guarded by the sino auricular valve, which possesses two flaps. The function of these valves is the prevention of the backflow of blood into the sinus venosus.
Considering the other options given:
-Sinus venosus: It is a cavity that is found incorporated into the right atrium of the heart. The sinus venosus forms the SA Node or the sino-atrial node, which generates the electrical impulses that lead to the contractility of the heart.
-Truncus-arteriosus: It is a type of heart disease, which has a rare incidence. In this disease state, a single blood vessel emerging out of the left and right ventricles are known as truncus-arteriosus, instead of two different vessels that are the aorta and pulmonary artery. This is a congenital heart disease, which is present from birth.
-Auriculo-ventricular aperture: It is a large opening, which is oval in shape and functions as a means of communication between auricles and ventricles.
Thus from the given set of options, the most appropriate answer was found to be B, that is the auriculo- ventricular valve is present in the edges of the auriculo- ventricular aperture.

Note: The SA node is also known as the sinoatrial node, is the natural pacemaker of the heart. It is a group of cells that are present in the upper part of the wall of the right atrium. It generates the impulses also known as an action potential, which travels all through the muscles of the heart and facilitates the contractility of the heart.