Final answer:
Endocrine signaling involves hormones traveling through the bloodstream to distant target cells. Paracrine signaling acts locally on nearby cells. Autocrine signaling occurs when a cell responds to its own signaling molecule.
Step-by-step explanation:
Endocrine signaling is a type of chemical signaling in which hormones are secreted into the bloodstream and travel to distant target cells to elicit a response. An example of endocrine signaling is the secretion of insulin by the pancreas to regulate blood sugar levels.
Paracrine signaling is a type of chemical signaling in which signals act locally on nearby cells. These signals move through the extracellular matrix and elicit quick responses that last for a short period of time. An example of paracrine signaling is the release of histamine by immune cells in the bronchial tree to constrict smooth muscle cells.
Autocrine signaling occurs when a cell responds to its own signaling molecule. It often occurs during early development to ensure proper tissue development and also regulates pain sensation and inflammatory responses. An example of autocrine signaling is a cell infected with a virus signaling itself to undergo programmed cell death to kill the virus.