The myelin sheath surrounding axons in brain is formed by ________.
Fill in the blank with the appropriate word.
Question 2
Neuromodulators are
a. rarely of a peptide form.
b. secreted from neurons, but dispersed widely in the brain.
c. inevitably inhibitory.
d. secreted from a neuron and only affect an adjacent neuron.
e. typically secreted in very small amounts compared to neurotransmitters.
