Membrane-04 Flashcards
What happens when a neurotransmitter diffuses across the synapse and binds to a receptor?
It binds to a specific receptor on the synaptic membrane, causing a shape change in the receptor
What are the two types of post synaptic receptors and what are their jobs?
Ionotropic receptors: directly opens ion channels
metabotropic receptors: activate metabolic cascades
Does the transmitter or receptor determine the effect?
The receptor determines the effect
What happens when a transmitter binds to an ionotropic receptor?
It directly opens an ion channel, causing a change in the post synaptic membrane potential
Which ions flow through the channel for EPSP and IPSP?
EPSP cations, like sodium and potassium depolarize
IPSP chloride or potassium hyperpolarize
What is an example of an ionotropic receptor?
Nicotinic receptor for acetylcholine
Which ions can act on ionotropic receptors
Acetylcholine, glutamate, GABA and glycine
What happens when a ligand binds to a metabotropic receptor?
It activates a G protein-coupled enzyme that produces or destroys second messengers like cAMP and cGMP
How do second messengers affect ion channels?
They activate enzymes like phosphokinases, which phosphoralate ion channels modulating ion current
Is the metabotropic effect faster, slow, and why?
Slow because it goes through metabolic steps before affecting the ion channels
What are the two types of summanation?
Spatial summation: multiple EPSPs from different synapses arrive at the same time
Temporal summation: High frequency EPSPs at one synapse build on each other
Where are PSP’s generated, can they initiate an action potential, why or why not?
PSP‘s are generated in the cell body and dendrites which lack voltage gated sodium channels, so they cannot initiate an action potential directly
Where are PSPs located and how do they affect EPSPs?
PSP’s are located in the soma, strategically shunting EPSP currents and making it harder for the cell to reach threshold
What happens when the chloride ion channels open during IPSPs?
The membrane potential is clamped near -70 MV preventing the polarization and inhibiting the neuron
What happens when there is continuous strong synaptic input?
A spike train of action potentials occur with repeating action potentials as depolarizing input last
