Which of the following substances is a hormone and a neurotransmitter?

Norepinephrine and epinephrine can have either excitatory or inhibitory effects on target organs.

__________ and __________ are the major neurotransmitters released by autonomic nervous system neurons.

Neurotransmitters released by sympathetic postganglionic fibers going to the heart would cause __________.

Which of the following neurons secrete norepinephrine?

Neuropeptides that act as natural opiates includea. substance P,b. somatostatin and cholecystokinin,c. tachykinins,d. enkephalins.

Receptors that bind acetylcholine at the postsynaptic membrane are (a) chemically gated channels, (b) voltage-gated channels, (c) passive channels, (d) mechanically gated channels.

Since at any moment a neuron is likely to have thousands of neurons releasing neurotransmitters at its surface, how is neuronal activity (to fire or not to fire) determined?

In the Netherlands a young man named Jan was admitted to the emergency room. He and his friends had been to a rave. His friends say he started twitching and having muscle spasms which progressed until he was 'stiff as a board.' On examination, staff found a marked increase in muscle tone and hyperreflexia involving facial and limb muscles. In his pocket, he had unmarked dark yellow tablets with dark flecks. Analysis of the tablets showed them to contain a mixture of ecstasy and strychnine. Ecstasy would not cause this clinical picture, but strychnine, which blocks glycine receptors, could. Explain how.