Adenoids are the lymphoid tissues in which:

The disease called pleurisy is due to:

Ravi,who lived at sea level,had around $5$ million $RBC$ per cubic millimeter of his blood. Later when he lived at an altitude of $18,000 \ ft$,he showed around $8$ million $RBC$ per cubic millimeter of blood. This is an adaptation because

Air pollution can result in emphysema,which is:

Which disease results in the lungs not receiving enough oxygen to survive?

In severe cases of which of the following diseases may the lips and fingernails turn gray to bluish in color?