1. Neurotransmitters

2. Review the Synapse
A synapse is the “gap” between the axon of one neuron and the dendrite of the next one.
The average neuron has 1,000 synapses with other neurons.

3. 1. Impulse from action potential opens ion channels for Ca++

4. 2. The increased Ca++ concentration in the axon terminal initiates the release of the neurotransmitter (NT)

5. 3. NT is released from its vesicle and crosses the “gap” or synaptic cleft and attaches to a protein receptor on the dendrite

6. 4. Interaction of NT and protein receptor open post-synaptic membrane ion channel for Na+

7. 5. After transmission the NT is either degraded by an enzyme or taken back into the pre-synaptic membrane by a transporter or reuptake pump

8. Neurotransmitters
There are dozens of different neurotransmitters (NT) in the neurons of the body.
NTs can be either excitatory (stimulate an action potential) or inhibitory (prevent an action potential by hyperpolarizing)

9. Acetylcholine (Ach) Excitatory
Controls muscles and regulates memory, learning, attention
used by the spinal cord neurons to control muscles and by many neurons in the brain to regulate memory

10. Dopamine
Usually inhibitory
Produced feelings of pleasure in the brain

11. Endorphins Reduces pain
Tends to be released when in pain, during exercise or laughing.
Name means “morphine-like substance produced inside the body

12. Epinephrine
Regulates attention, mental focus, arousal, metabolism, and cognition
Also called adrenaline
Hormone and neurotransmitter

13. Gamma-aminobutyric acid (GABA)
The major inhibitory neurotransmitter in the brain.
Reduces excess stimulation, improves focus, lessens anxiety

14. Glutamate The most common excitatory neurotransmitter in the brain.
Learning and memory

15. Norepinephrine Part of the flight-or-flight response in PNS.
In the brain, affects attention
Usually excitatory, but is inhibitory in a few brain areas.
Neurotransmitter and hormone

16. Serotonin Involved in mood, appetite, and sensory perception.
In the spinal cord, serotonin is inhibitory in pain pathways.

17. Drugs Interfere with Neuro-transmission

18. Drugs That Influence Neurotransmitters
Change in Neurotransmission
Effect on Neurotransmitter release or availability
Drug that acts this way
increase the number of impulses
increased neurotransmitter release
nicotine, alcohol, opiates
release neurotransmitter from vesicles with or without impulses
increased neurotransmitter release
amphetamines
methamphetamines
release more neurotransmitter in response to an impulse
nicotine
block reuptake
more neurotransmitter present in synaptic cleft
cocaine
amphetamine
block receptor with another molecule
no change in the amount of neurotransmitter released, or neurotransmitter cannot bind to its receptor on postsynaptic neuron
LSD
caffeine
NIH Publication No