Which of the following glands produces a hormone that stimulates cells in the immune system?

• A. Adrenal
• B. Thyroid
• C. Pineal
• D. Thymus

Answer: (D)

Verified step by step guidance

1. Understand the role of each gland mentioned in the question. The adrenal gland produces hormones like adrenaline and cortisol, which are involved in stress response and metabolism. The thyroid gland produces hormones like thyroxine (T4) and triiodothyronine (T3), which regulate metabolism. The pineal gland produces melatonin, which regulates sleep-wake cycles. The thymus gland, however, is involved in the immune system.
2. Recall that the thymus gland is a specialized organ of the immune system. It is located in the upper chest, just behind the sternum, and is most active during childhood and adolescence.
3. The thymus gland produces a hormone called thymosin. Thymosin plays a critical role in the development and differentiation of T-cells (a type of white blood cell), which are essential for adaptive immunity.
4. Recognize that the question asks for the gland that produces a hormone stimulating immune system cells. Based on the function of thymosin, the thymus gland is the correct answer.
5. Conclude that the thymus gland is the gland responsible for producing a hormone that stimulates cells in the immune system, specifically T-cells, which are vital for immune defense.