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Flashcards in Neurotransmission Deck (12):
1

Inhibitory Post-Synaptic Potential

Graded potential

Hyperpolarizing postsynaptic potential=influx of negative ions or effluent of positive ions

Usually from opening of Cl- or K+ channels

2

Excitatory post-synaptic potential

Graded potential caused by depolarizing post synaptic potential due to an influx of positive ions

Usually an opening of Na+ or Ca2+ channels.

3

Speed of propagation of action potential highest in axons that have....

Large diameter and increased myelination

Increases conduction velocity

4

Electrical synapse

Better fidelity of event transfer between neurons

Coordinated connection of large groups of neurons

Important for signaling in retina, glial cells, astrocytes, enteric NS

Direct physical connection allows for flow of ions between cells through gap junctions, which are made of many individual channels between cells

Transmit depolarizing and hyperpolarzing currents

Low resistance/high conductance pathway with near instantaneous transmission

5

Chemical Synapse

Rapid signal amplified in target

Excitatory or inhibitory

Neurons integrate their response from multiple inputs

Manipulated pharmacologically

Used in CNS and PNS

Synthesis and release of NTs causes ion channel to open on post-synaptic neuron resulting in post-synaptic potential

6

Molecular mechanisms of exocytosis-steps

1. Vesicle docks
2. SNARE complexes form to pull membranes together
3. Ca2+ enters and binds to synaptotagmin, a protein on the vesicle
4. Ca2+ bound synaptotagmin catalyzes membrane fusion by binding to SNAREs and the plasma membrane

7

Molecular mechanisms of endocytosis-steps

1. From inside the cell, clathrin is attached to to-be vesicular membrane using adaptor proteins
2. Clathrin triskelia assemble into a coat around vesicle to curve the membrane.
3. Dynamin forms a ring to pinch vesicle from membrane
4. Coated vesicle is translocated by actin filaments
5. HSBC-70 and auxiliary uncoat clathrin and dynamin from the vesicle.

8

Two families of post-synaptic receptors

1. Ligand gated/Ionotropic
2. G-protein-coupled/Metabotropic

9

Ligand-gated ion channels

Ionotropic

Used by ACh, glutamate, GABA, and glycine

NT receptor is major part

Very fast

1. NT binds
2. Channel opens
3. Ions flow across membrane

10

G-protein coupled receptors

Metabotropic

For biogenic amines (serotonin, dopamine, norepinephrine), ACh, glutamate, GABA, neuropeptides

Receptor is separate from ion channel

Functional, but not physical linkage: G-protein activation stimulates dissociation, which interacts with the ion channel

11

Mechanisms to deal with excess NT

1. Reuptake by specific transporters in presynaptic terminal or glial cells
2. Degradation by specific enzymes (ie acetylcholinesterase)

12

Definition neuropharmacology

Mechanism by which drugs affect the nervous system

Can affect synthesis, storage, release, reception (agonist/antagonist), or inactivation (reuptake inhibitor, degradation inhibitor)