Synaptic communication 1 (German) week 2 Flashcards
Resting membrane potential caused by?
Formation of a K+ concentration gradient
Permeability of the membrane to K+
What are the five types of Ion transporters and channels needed to send an action potential?
Na+/K+ ATPase Na+ ligand gated Na+ voltage gated K+ leaky channels K+ voltage gated
Neural membrane characteristics at rest
only permeable to K+
interior of neuron is negatively charged
exterior is positively charged
What is the Nernst Equation used for?
equilibrium potential of an individual ion
What is the Goldman Equation used for?
equilibrium potential of the entire plasma membrane
Passive current flow
current decays cytoplasmic resistance relative to distance Occurs IN: axons without channels cells bodies
Active Current Flow
current is repropagated
active process
relative to distance
Occurs in Axons
The action potential is caused by what?
- rapid change in membrane potential
- sequential opening of Na+ and K+ channels in a voltage and time dependent manner
voltage gated ion channels
- physical conformation changes with
- membrane polarization
- time and charge dependent
- ions move along their concentration gradient
- passive
- refractory period
Ligand gated ion channels
- ligand changes the conformation to allow ion movement
- many different ligands can cause change in protein
- ions move along concentration gradient
- passive
- open once sufficient ligand and appropriate environmental state is present
sodium potassium ATPase pumps
require energy and reestablish the membrane potential after an action potential
3 sodium out
2 potassium in
What are the steps of an action potential?
Na+ ligand open
Na+ volt open
Na+volt close and K+ volt open
K+ volt close and leaky K+ re-establish resting potential
Where are action potentials initiated?
axon hillock which is a Na volt. channel dense region.
What is the direction of an action potential?
anterograde and is unidrectional
What are two ways to increase an action potential
increase axon caliber
and increase myelination
What is multiple sclerosis caused by
demyelination
NT GABA is inhibitory of excitatory?
inhibitory
NT glutamate and dopamine are excitatory of inhibitory
excitatory
What are the 8 steps in synaptic transmission?
- action potential moves to terminal
- Calcium channel depolarization
- calcium influx
- synaptic vesicle fusion
- NT release
- NT receptor activation
- NT reuptake
- NT sequestration/Metabolism
What are the 3 distinct pools of synaptic vesicles?
- readily releasable
- recycling pool
- reserve pool
* listed in order of usage
What are the 4 proteins in the SNARE complex?
SNAP-25
Syntaxin
Synaptobrevin
Synaptotagmin
Which SNARE proteins are on the vesicle?
Synaptobrevin and Syanptotagmin(Calcium dependent)
Which SNARe proteins are on the vesicle?
SNAP-25 and Syntaxin
What are the two neurotransmitter receptor types?
Ionotropic- ligand gated ion channels
Metabotropic-G-protein coupled receptors
Ionotropic Neurotransmitter receptors
- ligand binding opens channel
- directly involved in creating postsyaptic electrical current and changing membrane potential
- Excitatory (depolarizing) or inhibitory(hyperpolarizing) done by chloride release.
Metabotropic neurotransmitter receptors
- G-protein coupled intracellular signals
- relatively slow activation time
- prolonged signal duration
- signals alter terminal structure and function
Excitatory Postsynaptic Potential (EPSP)
depolarization of the postsynaptic membrane
Ions released: Na+ and Ca2+
Inhibitory Postsnyaptic potential (IPSP)
hyperpolarization of postsynaptic membrane
Ion released: Cl- and K+
Summation definition
the total change in membrane potential based on the spatial and temporal aggregation of postsynaptic potentials
