Question

Which statement is true for the structure of the human heart?
A.The walls of atria are thin while the walls of ventricles are thick
B.There is a bicuspid valve between right atria and right ventricle
C.There is a tricuspid valve between left atria and left ventricle
D.The upper two chambers of heart are called ventricles and the lower two chambers are called atria

Answer 1

Hint: Human heart is a muscular organ. Along with blood vessels and blood, the heart forms the human circulatory system. It is also called a blood vascular system.

Complete answer:
 We know that there are four chambers in the human heart. The upper chambers are called auricles and the lower ones are called ventricles.Heart pumps blood which reaches all the tissues in the body through blood vessels. Atria is further divided into two chambers by a partition called inter atrial septum and ventricles by inter ventricular septum. Know that heart is derived from mesoderm. Atria and ventricles of the same side are also divided by a fibrous tissue. It is called atrioventricular septum

Walls of atria are thin while compared to walls of ventricles. It is because ventricles undergo vigorous contraction during ventricular systole so that blood is pumped outside and reaches all body parts.
The valve present between the right atrium and right ventricle is the tricuspid valve. A Bicuspid valve is present between the left atrium and left ventricle.

Additional information: Cardiac output is the amount of blood pumped by each ventricle in a minute. Amount of blood pumped out by each ventricle per heartbeat is known as stroke volume.

Hence the correct answer is OPTION(A)

Note: Tricuspid and bicuspid valves prevent the possible back-flow which would happen to the atria during ventricular contraction .
Other than these two, there is another valve called a semilunar valve that is present in the pulmonary artery and aorta.