Serotonin
<p>Oct 29, 2009 3:19 PM
Read Joh Allman's Evolving Brains on serotonergic system ... phyogen. very old ... maybe 800MYs or so?
System is in the BASEMENT OF THE HOUSE but extends everywhere to modulate and regulate wide variety
of activities (sleep and arousal; activity;  fires freq. with walking)
 
 
Oct 29, 2009 3:11 PM
 
sero in CNS regulates mood, appetite, sleep, muscle contraction and some learning: memory and learning.
 
80 to 90% of sero in human boyd is local. to the enterochromaffin cells in the gut
 
Neurons of the raphe nuclei are the main source of 5HT release in the brain - 9 pairs of nuclei
along entire length of the brainstem centered around the retic formation.
 
Their axons go everywhere.
 
<b>Serotonin is released from serotonergic varicosities (swellings) into the extra neuronal space</b>, but <b>not from synaptic terminal </b><a href="/wiki/Bouton" title="Bouton">boutons</a> as other neurotransmitters.<sup title="This claim needs references to reliable sources from June 2008" class="noprint Template-Fact" >[<a href="/wiki/Wikipedia:Citation_needed" title="Wikipedia:Citation needed"><i>citation needed</i></a>]</sup> Serotonin diffuses over a relatively wide gap (>20 µm) to activate <a href="/wiki/5-HT_receptor" title="5-HT receptor">5-HT receptors</a> located on the <a href="/wiki/Dendrite" title="Dendrite">dendrites</a>, cell bodies and <a href="/wiki/Presynaptic_terminal" title="Presynaptic terminal" class="mw-redirect">presynaptic terminals</a> of adjacent neurons.</p>