The endocrine system is made up of glands that release hormones into the bloodstream to regulate growth, metabolism, development, and other bodily functions. The major glands include the hypothalamus, pituitary, thyroid, parathyroid, adrenal glands, pancreas, and gonads. Together, these glands help control processes like temperature regulation, calcium levels, metabolism, and sexual development. Diseases can occur when the glands produce too much or too little hormones, such as diabetes, adrenal deficiencies, and hyperthyroidism.