Q.
During old age, the immunity of a person begins to decrease and as a result, they become more susceptible to infections and diseases. What could be the probable reason for this?
The thymus gland is responsible for the secretion of thymosins which play a major role in the differentiation of T-lymphocytes and provide cellular immunity. They also promote antibody production and provide humoral immunity. Hence, degeneration of the thymus gland in old age leads to decreased immunity.