1. Pituitary gland: Often called the "master gland," it releases hormones that control other endocrine glands. It also produces hormones that regulate growth, metabolism, and reproduction.

2. Thyroid gland: Located in the neck, this gland produces hormones that regulate metabolism, heart rate, and body temperature.

3. Adrenal glands: Situated on top of the kidneys, these glands produce hormones like cortisol (stress response) and adrenaline (fight-or-flight response).

4. Pancreas: This organ has both endocrine and exocrine functions. Its endocrine function is to produce insulin and glucagon, which regulate blood sugar levels.