Thymus Gland and Immune Development — NEET Biology
📚 Practice ConceptThe thymus gland is a lobular structure located between lungs behind sternum on the ventral side of aorta. The thymus plays a major role in the development of the immune system. This gland secretes the peptide hormones called thymosins. Thymosins play a major role in the differentiation of T-lymphocytes, which provide cell-mediated immunity. In addition, thymosins also promote production of antibodies to provide humoral immunity. Thymus is degenerated in old individuals resulting in a decreased production of thymosins. As a result, the immune responses of old persons become weak.
Which of the following statements concerning the thymus gland and its hormones are correct? S1: The thymus gland is a lobular structure located between the lungs behind the sternum on the ventral side of the aorta. S2: Thymosins are peptide hormones secreted by the thymus gland that promote the differentiation of T-lymphocytes. S3: T-lymphocytes are primarily responsible for providing humoral immunity by producing antibodies. S4: The immune responses of old persons typically become stronger due to the continued activity of the thymus throughout life. S5: Thymosins also enhance the production of antibodies, thereby contributing to humoral immunity.
View solution & NCERT explanation
Correct answer: B — S1, S2 and S5 only
S1 is correct. "The thymus gland is a lobular structure located between lungs behind sternum on the ventral side of aorta." S2 is correct. "This gland secretes the peptide hormones called thymosins. Thymosins play a major role in the differentiation of T-lymphocytes". S3 is incorrect. T-lymphocytes provide cell-mediated immunity, while B-lymphocytes are primarily responsible for humoral immunity by producing antibodies. S4 is incorrect. The thymus gland degenerates in old individuals, leading to a decreased production of thymosins and weakened immune responses. S5 is correct. "In addition, thymosins also promote production of antibodies to provide humoral immunity." Therefore, S1, S2, and S5 are correct. This question tests the structural location, hormonal secretions, and immunological roles of the thymus gland.
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