Question

Choose the correct statements :
I. The heart is a hollow organ present in the thoracic cavity
II. The pulmonary veins are guarded by valves which prevent the backflow of blood.
III. The walls of the left ventricle are about three times thicker than the right ventricle.
IV. Pulmonary arteries carry deoxygenated blood to the lungs
V. The foetal heart has an opening between two atria

• A. I, III, IV and V only
• B. II only
• C. I, III and IV only
• D. All of the above

Answer 1

The correct option is A I, III, IV and V only

Heart is a hollow, fibromuscular organ present in the thoracic cavity. The walls of ventricles are much thicker than the atria. Between the two ventricles, the left ventricle has even three times thicker walls than the right ventricle, as it pumps out the oxygenated blood to all the body parts with high pressure.

The arteries generally carry oxygenated blood from the heart to the organs. But the pulmonary arteries are the exceptions and they carry deoxygenated blood pumped by the right ventricle of the heart to the lungs. The blood gets oxygenated in the lungs as a result of gaseous exchange and then it returns back to the heart through pulmonary veins which carries the oxygenated blood. The openings of these veins are not guarded by any valves.

At the foetal stage, the lungs are non-functional, so the blood circulation is by-passed and blood reaches the left atrium directly from the right atrium through foramen ovale. Foramen ovale is an opening between the two atria which gets closed at the time of birth and leaves an oval depression there which is known as fossa ovalis.
So only statement II is not correct.