Option E.4 Neurotransmitters & Synapses
Page 360
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
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)
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.
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.
Psychoactive drugs
• Before we talk about how drugs affect the brain & personality, we need to have a fundamental understanding of two neurotransmitters: – Acetylcholine – Noradrenaline
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”
What’s amphetamine?
• Adderall (ADHD/cognitive control)• Sometimes prescribed “off label” for
depression, obesity & nasal congestion
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
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
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.
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.
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