Exocrine glands, such as sweat and salivary glands, secrete externally and internally via ducts. Endocrine glands secrete hormones internally, using the bloodstream.) The endocrine system helps control the following processes and systems: Growth and development.

The endocrine glands do not have ducts to carry their product to a surface. They are called ductless glands. The word endocrine is derived from the Greek terms “endo,” meaning within, and “krine,” meaning to separate or secrete.

Structure. Exocrine glands contain a glandular portion and a duct portion, the structures of which can be used to classify the gland. The duct portion may be branched (called compound) or unbranched (called simple). The glandular portion may be tubular or acinar, or may be a mix of the two (called tubuloacinar).

The cells in these glands secrete specific chemicals called hormones. Hormones that stimulate and control the activity of other endocrine glands are called trophic hormones.

The pituitary gland

Hormones and the Endocrine System

Hormones are produced by glands and sent into the bloodstream to the various tissues in the body. They send signals to those tissues to tell them what they are supposed to do. When the glands do not produce the right amount of hormones, diseases develop that can affect many aspects of life.

Levels of testosterone and other androgens can be measured with a blood test. In women, normal testosterone levels range from 15 to 70 nanograms per deciliter (ng/dL) of blood. Testosterone levels lower than 15 ng/dL may cause: changes in breast tissue.

Research shows that the hormone testosterone may improve sexual function in specific groups of women, but data on safety and effectiveness are limited. The long-term safety of testosterone therapy for women also is unknown.