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The Nervous System-Part II. Neurotransmitters, Drugs and Disease of the Brain. Neurotransmitters. Excitatory neurotransmitters Increase postsynaptic membrane permeability to Na+ Threshold is reached for message to be sent Inhibitory neurotransmitters Decrease permeability to Na+
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The Nervous System-Part II Neurotransmitters, Drugs and Disease of the Brain
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.
First neurotransmitter discovered (1921) Excitatory 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 Acetylcholine (ACH)
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! Glutamate
Serotonin • Found in the brain • 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
Dopamine • 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
Dopamine - cont’d • Dopamine also sends signals that help coordinate your skeletal muscle movements • Parkinson’s Disease • deficient dopamine production • tremors
Found in the brain Inhibitory 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 GABA
Found in the brain Alertness, regulation of moods Norepinephrine
Endorphins • 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
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