Suppose that substance X is secreted by one cell, travels via interstitial fluid to a neighboring cell, and produces an effect on that cell. All of the following terms could describe this substance except
A) paracrine signal.
B) neurotransmitter.
C) prostaglandin.
D) pheromone.
E) growth factor.

Question

Quizplus · Accepted Answer

Pheromones are chemical signals released by an organism into the environment, affecting the behavior or physiology of other members of the same species, not signals that act on neighboring cells through interstitial fluid. Paracrine signals, neurotransmitters, prostaglandins, and growth factors all involve local signaling mechanisms, unlike pheromones which involve external signaling.

Suppose That Substance X Is Secreted by One Cell, Travels