Lecture 6: Synaptic Mechanism

what determines the voltage of a neuron?

all the epsps and ipsps that the dendrites are taking in

what is the transfer of potential down a neuron

action potential propagates down the axon, myelinated its graded potential and unmyelinated is action potential

what happens when the Ca+2 ion channels open?

the Ca2+ come in and allow the vesicles to dock and open at axon terminal

what is axo-somatic

synapse between a soma and axon

What is a axo-axonic synapse?

synapse between a axon and axon

What is axo-dendritic synapse?

synapse between a dendrite and axon

What is an epsp ?

EPSP: Excitatory Post Synaptic Potential; opens non-specific cation channel & depolarizes neuron

like Na+

what is an IPSP?

Needed for regulation. Results in hyperpolarization and makes it harder to reach the threshold. (membrane may become more permeable to K+ and Cl- ions)

IPSP: Inhibitory Post Synaptic Potential; increases permeability of potassium & hyperpolarizes neuron

What are ionotropic receptors?

ligand-gated ion channels that open when ligand binds

What are metabotropic receptors?

G-protein coupled receptors, 2nd messenger is released form membrane and allow for a much longer effect

can change membrane potential!

32 diff responses possible

Glutamate and GABA can both work on metabotropic and ionotropic receptors

true

Which conditions brings the neuron closer to the threshold to fire an action potential?

EPSP, Sodium in, depolarized (above -70mV)

what is the processing in the presynaptic neuron?

all-or-none, binary

either release neurotransmitters or don't

what are the 3 responses on the post-synaptic cell

depolarizing (EPSP)

flat (equal rates)

hyperpolarize (IPSP)

what do acetylcholine (and ACh receptors)do?

neuro-muscular junction, activates muscle contractions

in peripheral system

what conditions bring the neuron further from threshold?

hyperbolizing IPSP, like K+ eflux or Cl- influx

what do amino acid neurotransmitters do?

work at ionotropic

GABA is an IPSP

glutamate is an EPSP

What are monamines?

1. Monoamines are regulatory molecules derived from amino acids

2. Catecholamines: derived from tyrosine; include dopamine, norepinephrine, and epinephrine

3. Serotonin: derived from L-tryptophan

4. Histamine: derived from histidine

what are the two ways to remove neurotransmitters from the synapse?

1. reuptake back into the presynaptic neuron

2. an enzyme breaks them down into components

how does QUANTA function to release neurotransmitters?

they release neurotransmitters in packets of whole numbers, and normally same amount

release in "Quantas"

What does Dale's Law state?

each neuron releases 1 type of neurotransmitter (dopaminergic),

but each vesicle can have different compositions of neurotransmitters

more possible combinations