The correct option is Pituitary.
Explanation
The endocrine system comprises various glands that secrete hormones directly into the bloodstream to regulate physiological functions. Growth Hormone (GH), also known as Somatotropin, is a critical peptide hormone responsible for stimulating growth, cell reproduction, and cell regeneration in humans and other animals.
Option Analysis:
- Pituitary Pituitary: Correct. Growth Hormone is secreted by the anterior lobe of the pituitary gland (adenohypophysis). The pituitary gland is often referred to as the "master gland" because it controls the function of several other endocrine glands. GH plays a vital role in physical development, particularly during childhood and adolescence, and regulates body composition, fluids, muscle and bone growth, and metabolism.
- Thyroid Thyroid: Incorrect. The thyroid gland, located in the neck, primarily secretes Thyroxine (T4) and Triiodothyronine (T3), which regulate the body's metabolic rate, heart rate, and digestive function.
- Adrenal Adrenal: Incorrect. The adrenal glands, located on top of the kidneys, secrete hormones such as Adrenaline (Epinephrine), Cortisol, and Aldosterone. These are involved in the stress response ("fight or flight"), metabolism, and blood pressure regulation.
- Pancreas Pancreas: Incorrect. The pancreas functions as both an exocrine and endocrine gland. Its endocrine function involves the secretion of Insulin and Glucagon from the Islets of Langerhans to regulate blood glucose levels.
Key Takeaway:
Growth Hormone (Somatotropin) is produced and secreted by the anterior pituitary gland. It is essential for longitudinal bone growth and protein synthesis.