Question

If due to some injury, the chordae tendineae of the tricuspid valve of the human heart is partially non-functional, what will be the immediate effect?
(a) The flow of blood into the aorta will be slowed down
(b) The ‘pacemaker’ will stop working
(c) The blood will tend to flow back into the left atrium
(d) The flow of blood into the pulmonary artery will be reduced.

Answer 1

Hint: Human heart is four-chambered i.e. two atria and two ventricles. The main function of bicuspid and tricuspid valves is to prevent the backflow of blood from ventricles to atria of their own respective sides. If the function of these valves is hampered, the blood will flow back into the atria and consequently, the further flow of blood from the ventricle to major vessels will get affected.

Complete answer:
The tricuspid valve is present in between the right atrium and the right ventricle. The right side of the heart is concerned with deoxygenated blood which comes from all parts of the body and is sent to the lungs for oxygenation. In the double circulation observed in the human heart, the right atrium receives deoxygenated blood from all parts of the body via the superior and inferior vena cava. It is then sent into the right ventricle from where it will be sent for oxygenation to the lungs via the pulmonary artery. The opening between the right atrium and right ventricle is guarded by the tricuspid valve. It has the name due to its flaps which look like cusps and are three in number. The flaps are held tightly by fibrous structures called chordae tendineae. When the chordae tendineae contract, they pull all the three cups downwards thereby opening the tricuspid valve, and hence blood enters the right ventricle. So, if there is some damage to the chordae tendineae, the immediate effect would be the backflow of blood into the atria. Consequently, the flow of blood into the pulmonary artery will be reduced since blood will keep going back into the atria.
So the correct answer is, ‘the flow of blood into the pulmonary artery will be reduced’.

Note: Chordae tendineae are in turn held tightly by the papillary muscles. The papillary muscles are intricately connected to the walls of the right ventricle. The signal to contract or expand comes from the AV node and then through the Purkinje fibers which then cause the chordae tendineae to contract or relax.