Final answer:
In the nervous system, mediator molecules are neurotransmitters, whereas in the endocrine system, hormones serve as the mediator molecules.
Step-by-step explanation:
Neurotransmitters play a crucial role in transmitting signals within the nervous system. These are chemical messengers that facilitate the transmission of nerve impulses across synapses, the junctions between nerve cells. For example, acetylcholine, dopamine, and serotonin are neurotransmitters involved in various functions such as muscle contraction, mood regulation, and cognition. The release of neurotransmitters is a highly localized and rapid process, allowing for precise communication between neurons.
On the other hand, the endocrine system primarily uses hormones as mediator molecules. Hormones are secreted by endocrine glands into the bloodstream, allowing them to travel throughout the body to target cells or organs. This widespread distribution enables hormones to regulate various physiological processes, including metabolism, growth, and reproductive functions. Examples of hormones include insulin, cortisol, and estrogen. Unlike neurotransmitters, the action of hormones is typically slower and more prolonged, providing a systemic and sustained influence on the body's activities.
In summary, while neurotransmitters are specific to the nervous system and act locally at synapses, hormones are the mediator molecules in the endocrine system, exerting their effects systemically through the bloodstream. The distinct roles of neurotransmitters and hormones highlight the intricate coordination between the nervous and endocrine systems in maintaining physiological balance and responding to internal and external stimuli.