Paracrine signals
A) act on the cells that made them.
B) move through the blood and act on cells far from their source.
C) act on cells that are near to those that secrete them.
D) do not act through receptors.
E) require large concentrations of the signaling molecule to function.

Question

Quizplus · Accepted Answer

Paracrine signals act on cells that are near to those that secrete them, but not necessarily on the cells that made them. They do not move through the bloodstream to act on cells far from their source, which would be considered endocrine signaling. Paracrine signaling does require receptors on the target cells to respond to the signal. Larger concentrations of the signaling molecule may be needed for a response in some cases, but this is not a defining feature of paracrine signaling.

Paracrine Signals