2. What is a neurotransmitter? Chemicals secreted by neurons Stimulated action potential in adjacent neurons Two types of responses: Excitatory Inhibitory

3. Types of Responses Excitatory: Opens sodium gates Starts a nerve impulse Inhibitory Makes neuron more negative on inside Raises Threshold Requires more stimulus to start a nerve impulse

4. Summation Effect produced by the accumulation of neurotransmitters from two or more neurons

5. EXAMPLES NeurotransmitterExcitatory or Inhibitory Effect AcetylcholineBoth excitatory and inhibitory Involved with somatic & parasympathetic nervous systems Stimulates skeletal muscles Inhibits cardiac muscles Norepinephrine (noradrealine) Excitatory Involved with sympathetic nervous system

6. NeurotransmitterExcitatory or Inhibitory Effect GlutamateExcitatory Cerebral cortex (brain) excitatory transmissions 75% of all transmissions GABA (Gamma aminobutyric acid) Inhibitory Cerebral cortex inhibitory transmissions DopamineExcitatory Elevates mood Controls skeletal muscles SeratoninInhibitory Involved in alertness, sleepiness, mood, thermoregulation

7. Disorders Alzheimer’s Disease Low acetylcholine Parkinson’s Disease Low dopamine

8. Drugs…. Which are good? Which are bad? Prescription drugs Made to alter neurotransmitter release Addictive drugs Interfere with neurotransmitters Produce feeling of pleasure Release dopamine

9. Prescription Drugs Valium Increases GABA Result: alleviate anxiety Prozac Enhances serotonin Result: antidepressant

10. Drug and Poison Overview Muscle paralysis E.g. Nerve gas, botulin toxin, some insecticides Result: disrupts acetylcholine Stimulants Mimics norepinephrine Result: alertness, excitement Depressants Block norepinephrine formation Result: slows body activity, depression Hallucinogens Interferes with serotonin

11. Methamphetamine Enters synaptic vessicles Causes dopamine release Blocks dopamine from reentering synaptic knob Result: Increased pleasure

12. Cocaine Enters synapse Blocks dopamine from reentering synaptic knob Result: Increased pleasure

13. Nictoine Binds to receptor on presynaptic neuron Causes more dopamine to be released