What term means chemical messengers that cross the synaptic gaps between neurons?

• A. Neurotransmitters
• B. Hypochondriasis
• C. Blepharoptosis
• D. Paresthesia

Answer: (A)

Chemical messengers that cross the synaptic gaps between neurons are neurotransmitters. When a neuron fires, it releases these chemical signals from vesicles into the tiny space between neurons. They diffuse across the synaptic cleft and bind to receptors on the next neuron, which can make that neuron more likely to fire or less likely, depending on the type of neurotransmitter and receptor involved. This precise chemical communication underpins all nervous system signaling. The other terms describe conditions or symptoms rather than messengers: hypochondriasis is excessive illness worry, blepharoptosis is drooping of the eyelid, and paresthesia is abnormal sensations like tingling.