1. Endocrine glands: These are specialized organs that produce and secrete hormones directly into the bloodstream. Examples include the pituitary gland, thyroid gland, adrenal glands, pancreas, and gonads.

2. Hormones: These are chemical messengers that are produced by endocrine glands and travel through the bloodstream to target cells or organs. Hormones regulate a wide variety of bodily functions, including growth, metabolism, reproduction, and mood.