Which of the following organs is NOT considered a primary endocrine organ?

• A. Pancreas
• B. Adrenal gland
• C. Heart
• D. Thyroid gland

Answer: (C)

Verified step by step guidance

1. Step 1: Understand the concept of primary endocrine organs. Primary endocrine organs are those whose main function is to produce and secrete hormones directly into the bloodstream to regulate various physiological processes.
2. Step 2: Review the listed organs and their primary functions. The pancreas, adrenal gland, and thyroid gland are all primary endocrine organs because their main role is hormone secretion (e.g., insulin from the pancreas, cortisol from the adrenal gland, and thyroid hormones from the thyroid gland).
3. Step 3: Examine the heart's function. The heart is primarily a muscular organ responsible for pumping blood throughout the body. While it does produce a hormone called atrial natriuretic peptide (ANP), its primary function is not endocrine in nature.
4. Step 4: Differentiate between primary and secondary endocrine functions. Secondary endocrine organs, like the heart, produce hormones as a secondary function, not as their main role.
5. Step 5: Conclude that the heart is not considered a primary endocrine organ because its main function is related to the circulatory system, not hormone production.