Option E.4 Neurotransmitters & Synapses

1. Option E.4 Neurotransmitters & Synapses Page 360

2. Synaptic Transmission • Neurons communicate with each other chemically across a space called a synapse • Presynaptic membrane • Sending • Postsynaptic membrane • Receiving • The molecule moving across the space (synaptic cleft) is called a neurotransmitter

3. Neurotransmitters • Some NTs are excitatory • Stimulate the next neuron to forward the message • Increase the permeability to positive ions (positive ions move in) • Some NTs are inhibitory • They cause positive ions to move out of the postsynaptic cell • Movement of positive ions back into the synaptic cleft chemically depresses the postsynaptic cell (harder to excite)

4. Question • When two neurons communicate with each other, the presynaptic neuron sends a message across the synapse to the postsynaptic neuron. • 1. What type of molecule carries the message across the synapse and what type of molecule receives the message? • 2. Explain the two ways that presynaptic neurons can act on postsynaptic neurons.

5. Decisions, decisions • What interaction occurs between excitatory and inhibitory presynaptic neurons acting at the synapse? • Open your book to page 361. Read pages 361-362. Then answer the following questions: • In your own words, outline the steps of decision making in the central nervous system. • Identify an excitatory neurotransmitter. Outline how an excitatory neurotransmitter works. • Identify an inhibitory neurotransmitter. Outline how an inhibitory neurotransmitter works.

6. Psychoactive drugs • Before we talk about how drugs affect the brain & personality, we need to have a fundamental understanding of two neurotransmitters: • Acetylcholine • Noradrenaline

7. Cholinergic vs. Adrenergic Synapses • Synapses using acetylcholine are called cholinergic synapses • Nicotine, for example, stimulates transmission in cholinergic synapses  calming effect • “C” • Synapses using noradrenaline are called adrenergic synapses • Cocaine & amphetamines stimulate adrenergic synapses  increased alertness, energy & euphoria • “A”

8. What’s amphetamine? • Adderall (ADHD/cognitive control) • Sometimes prescribed “off label” for depression, obesity & nasal congestion

9. Effect of drugs on the brain • Drugs can alter your mood & emotional state • Excitatory drugs like nicotine, cocaine and amphetamine increase nerve transmission • Inhibitory drugs like benzodiazepines, alcohol and tetrahydrocannabinol(THC) decrease likelihood of nerve transmission

10. How can drugs change synaptic transmission? • Block a receptor for a neurotransmitter • Block release of a neurotransmitter • Enhance release of a neurotransmitter • Enhance neurotransmission by mimicking a neurotransmitter • Block removal of a neurotransmitter from the synapse and prolong the effects of the NT

11. EXCITATORY!!!! DRUGS • Turn to page 365. • Explain the effects of nicotine, cocaine and amphetamine in terms of their actions at the synapses in the brain.

12. Inhibitory Drugs • Turn to page 366. • Explain the effects of GABA, alcohol and THC in terms of their actions at the synapses in the brain.