The Synapse, Drugs and Toxins

Physiological Psychology Lesson Three

What are the two main structures involved in a synapse?

The presynaptic axon terminal and the postsynaptic dendritic spine.

What separates the presynaptic and postsynaptic membranes?

The synaptic cleft, maintained by adhesion molecules.

What are neurotransmitters and where are they released from?

Neurotransmitters are chemical messengers released from the presynaptic terminal.

Name three categories of amine neurotransmitters and examples of each.

Catecholamines (dopamine, norepinephrine, epinephrine), Indoleamines (serotonin, melatonin), and Acetylcholine.

Which neurotransmitters are classified as amino acids?

GABA, glutamate, and glycine.

What role do SNARE proteins play in neurotransmitter release?

They assist in docking and priming vesicles at the active zone for neurotransmitter release.

What is the Readily Releasable Pool?

It contains docked and primed vesicles ready for immediate release at the active zone.

How does calcium influence neurotransmitter release?

Calcium influx triggers SNARE proteins to release neurotransmitters via calcium-triggered exocytosis.

What are ionotropic receptors?

Receptors that are directly linked to ion channels, causing fast and short-lived responses.

What is the difference between ionotropic and metabotropic receptors?

Ionotropic receptors directly open ion channels; metabotropic receptors use G-proteins and cause slower, longer-lasting effects.

What is an EPSP?

An excitatory postsynaptic potential that depolarizes the postsynaptic membrane, bringing it closer to threshold.

What is an IPSP?

An inhibitory postsynaptic potential that hyperpolarizes the postsynaptic membrane, moving it away from threshold.

What is temporal summation?

The summing of multiple EPSPs from a single neuron in rapid succession.

What is spatial summation?

The combining of EPSPs from multiple neurons at different synapses simultaneously.

What is the role of astrocytes in the tripartite synapse?

Astrocytes take up and recycle neurotransmitters, release gliotransmitters, and help maintain ion balance.

What is an electrotonic synapse?

A synapse that transmits signals via gap junctions without neurotransmitters.

How do sodium channel blockers like tetrodotoxin affect neurons?

They prevent action potentials by blocking sodium channels, halting neural communication.

What is a quad-partite synapse?

A synapse that includes the presynaptic axon, postsynaptic dendrite, astrocyte, and microglia.

What is the mechanism of action of botulinum toxin?

It cuts SNARE proteins, preventing vesicle fusion and neurotransmitter release, leading to muscle paralysis.

What is reuptake inhibition?

A mechanism where transporters are blocked, increasing neurotransmitter levels in the synapse.

How does ecstasy (MDMA) affect the brain?

It blocks and reverses monoamine transporters and inhibits MAO, increasing serotonin, dopamine, and norepinephrine levels.

How does ketamine act as an antidepressant?

Its metabolite activates AMPA receptors, promoting excitatory activity and rapid antidepressant effects.

What is the primary action of caffeine in the brain?

It blocks adenosine receptors, leading to increased excitatory neurotransmitter and dopamine activity.

How does alcohol affect neurotransmitter systems?

It modulates GABA, glutamate, serotonin receptors, and blocks calcium channels, suppressing neural activity.