Following are some of the ways that the endocrine system can use different types of hormones to signal or communicate with cells in various parts of the body:
- Paracrine signaling involves hormones that are released from cells and directed towards target cells located in close proximity to the cells that released the hormone.
- Autocrine signaling involves hormones that are released by a cell that targets itself, with the purpose of increasing cell function or expression of certain genes and proteins.
- Juxtacrine signaling involves hormones that are released from one cell and directed toward another cell in close contact via ligands, anchoring proteins, or extracellular matrices.
Not all cells are located closely together and some must travel further distances. To accomplish this goal, hormones are transported freely in serum or augmented to special transport proteins and sent to the target cell via the circulatory system depending on the class of hormone.
