1. The Nervous System-Part II
Neurotransmitters

2. Action Potentials Target Neurotransmitter Release

3. Neurotransmitters Found in CNS and PNS Over 100 in the body
Can be excitatory or inhibitory
Once released neurotransmitters will be decomposed by enzymes or up-taken by transporters in the pre-synaptic membrane
Classified as: acetylcholine, monoamines, amino acids, neuropeptides and gases

4. Excitatory vs. Inhibitory Neurotransmitters
Excitatory neurotransmitters
Increase postsynaptic membrane permeability to Na+
Threshold is reached for message to be sent
Inhibitory neurotransmitters
Decrease permeability to Na+
Decreases chance nerve impulse will occur.

5. Acetylcholine (ACh) First neurotransmitter discovered (1921)
Excitatory in the CNS and PNS
Skeletal muscle neuromuscular junctions & synapses between the brain and spinal cord
Message causes muscles to contract or continues impulses
Nicotine inactivates ACH receptors and causes brain to create more receptors

6. Glutamate Found in the CNS, generally excitatory
helps send messages in the brain
Involved in learning and memory
Alcohol inhibits glutamate receptor function
Monosodium Glutamate (MSG) is a food additive that stimulates glutamate receptors in the taste buds!

7. Serotonin Found in the CNS, primarily inhibitory
Responsible for sleep, mood and temperature regulation
Antidepressants (Prozac, Zoloft, Paxil, etc) work by allowing serotonin to accumulate in the synapse,
“SSRI’s” or Selective Serotonin Reuptake Inhibitors
feel more content
LSD mimics serotonin, and MDMA releases excess serotonin

8. Dopamine CNS and PNS, primarily excitatory AKA “the brain reward”
Regulates emotions, moods and subconscious control of skeletal muscle
Reward Pathway
Cocaine
interferes with the process by which dopamine is taken back up (leaves more in the synapse)
Methamphetamine
excess dopamine release

9. Dopamine - cont’d
Dopamine also sends signals that help coordinate your skeletal muscle movements
Parkinson’s Disease
deficient dopamine production
tremors

10. GABA CNS, generally inhibitory Found in the brain
Prevents the receptor nerve from being overstimulated
When it accumulates it has a sedative effect
Valium, Xanax and Ativan work by allowing GABA to accumulate
More GABA, more relaxed

11. Norepinephrine CNS and PNS, primarily excitatory
Found in the brain, promotes feeling good, low levels linked to depression
Alertness, regulation of moods
In the PNS may excite or inhibit based on receptors

12. Endorphins Primarily inhibitory, cause release of substance P
Flood the synaptic cleft during pain or stress
Usually inhibit neurons from firing, causing an analgesic effect
At lower levels can excite the next neuron
Reduces pain and makes one feel good
“Opiates” (heroin, codeine, morphine, oxycodone, hydrocodone, etc)
bind to endorphin receptors and mimic endorphins

13. Anandamide
Involved in working memory, regulation of feeding behavior, generation of motivation and pleasure
Anandamide receptors are called cannabinoid receptors
A lot of cannabinoid receptors in the hippocampus (short term memory), cerebellum (coordination) and basal ganglia (unconcious muscle movement) of brain
THC (found in marijuana) mimics anandamides and binds to cannabinoid receptors
How Marijuana Works in the Brain