Question

In which part of the body blood gets purified (becomes oxygenated)
A. Atrium
B. Lungs
C. Heart
D. Ventricle

Answer 1

Hint: Human beings show aerobic respiration i.e. it involves the use of molecular oxygen and release of carbon dioxide simultaneously. They show indirect and pulmonary type of respiration i.e. the exchange of gases occurs through lungs.

Complete answer:
> Heart is a thick, muscular, automatic pulsating and contractile organ that receives blood through veins from different body parts and distributes blood to various body parts via arteries. It is situated in the thoracic cavity of the body. Two auricles and two ventricles together form the four chambers in the human heart.
> Auricles of atria are thin walled chambers that are separated from each other by interatrial septum. Right auricle is larger in size and it receives deoxygenated blood from the body. Left auricle is smaller in size and it receives oxygenated blood from lungs by four pulmonary veins.
> Ventricles are thick walled as they have to push the blood to all body parts. From the left anterior corner of the right ventricle, there originates the pulmonary arch or pulmonary aorta which carries deoxygenated blood to the lungs. From the right anterior corner of left ventricles there originates an aortic or systemic arch which carries oxygenated blood to various body parts.
> Lungs are the respiratory organs that help in the gaseous exchange in the body. These are present in the thoracic cavity and each lung is enclosed in two membranes, called the pleura. The inner membranes are called the visceral pleura and the outer layer is called the parietal pleura. A very narrow space exists between the two pleura called the pleural cavity which is filled by the pleural fluid.
> In the lungs the exchange of gases between the air in the alveoli and the blood in the capillaries around the alveoli. In this exchange, the blood takes up oxygen from the alveolar air and releases carbon dioxide to the alveolar air.

So the correct answer is B. Lungs.

Note: Lungs have little musculature and cannot expand or contract on their own. It is brought about by alternate expansion and contraction of the thoracic cavity. This leads to intake of fresh air called inspiration and elimination of foul air through expiration.