[Campbell Biology P.264] Which of the following statements best describes the primary differ... | Practice Question
Which of the following statements best describes the primary differences among paracrine, synaptic, and endocrine signaling?
A: Paracrine signaling involves direct contact between cells, while synaptic and endocrine signaling use secreted molecules.
B: Synaptic signaling is specialized for the nervous system, paracrine signaling affects nearby cells, and endocrine signaling uses hormones transported through the bloodstream to distant targets.
C: Endocrine signaling is a type of local signaling, whereas paracrine and synaptic are long-distance.
D: Only synaptic signaling involves electrical signals, while paracrine and endocrine rely solely on chemical signals.
Explanation
Paracrine signaling involves local regulators acting on nearby cells. Synaptic signaling is a specialized local signaling in the nervous system, where neurotransmitters diffuse across a synapse. Endocrine hormonal signaling is long-distance, with hormones traveling through the circulatory system to distant target cells. Option B accurately summarizes these distinctions.