Many adults living in the US become curious about doctor prescribed growth hormone replacement therapy when they begin to experience chronic symptoms, such as low energy, fatigue and low sex drive, that are frequently associated with your bodyâs declining growth hormone levels.
External, or exocrine, secretion is distinguished from internal, or endocrine, secretion. In external secretion the products elaborated by a gland are released into the external environment; the secretion first enters the glandular duct, from which it is discharged onto the surface of the body or into hollow organs.
The synthesis and release of chemical substances by cells or glands. Substances secreted include enzymes, hormones, lubricants, surfactants and neurotransmitters. Internal secretion is secretion into the bloodstream. External secretion may be into the intestinal canal or other organs or on to the skin. Compare EXCRETION. 1  the process by which a useful substance produced in a cell is passed through the plasma membrane to the outside.  the substance itself.