Lecture 3 Flashcards
Neurons communicate by transmitting chemicals where?
Junctions called Synapses
What cells deliver the message?
Presynaptic Neuron
What cell receives the message?
Postsynaptic Neuron
What are chemicals that travel across the synapse and allow communication between neurons
Neurotransmitters
The neuron synthesizes chemicals that serve as what?
Neurotransmitters
After neurons are synthesized the action potential travels where?
Down the axon
After action potentials travel down the axon, it releases what?
Molecules to diffuse across the cleft, attach to receptors and alter activity of postsynaptic neuron
After molecules diffuse across the cleft, the neurotransmitter does what?
Seperate from the receptors of postsynaptic neurons
After the neurotransmitters seperate they will be taken where?
Back into presynaptic neuron for recycling or diffuse away.
Some postsynaptic cells send reverse messages for what?
To slow the release of further neurotransmitters by presynaptic cells.
What are some types of neurotransmitters?
Glutamate Acetylcholine Serotonin Epinephrine ETC.
Neurons synthesize neurotransmitters and other chemicals from substances provided by what?
Diet
What is a precursor for serotonin?
Tryptophan
What contains a catechol group and an amine group?
Catecholamines
What are tiny spherical packets located in presynaptic terminal where neurotransmitters are held for release?
Vesicles
What breaks down excess levels of some neurotransmitters?
MAO (Monoamine Oxidase)
What are bursts of release of neurotransmitter from the presynpatic terminal into the synaptic cleft?
Exocytosis
Exocytosis is triggered by what?
Action Potential
Transmission by neurotransmitter across synaptic cleft takes how long?
Fewer than 0.01ms
Most individual neurons release at least what?
Two or more different neurotranmitters
Nerons may also respond to what/
More types of neurotransmitters than they release
The effect of a neurotransmitter depends on what?
Receptor on postsynaptic cell
What’s controlled by a neurotransmitter?
Transmitter-gated or Ligand-gated channels
What occurs when a neurotransmitter attaches to receptors and immediately open ion channels
Ionotropic Effects
Ionotropic effects occur how?
Very quickly and are short lasting
Ionotropic effects rely on what?
Glutamate or GABA
What affects much of the cell, opens or closes ion channels, changes protein production or activates chromosomes in the cell
Second Messenger Systems
Neurotransmitters released into synapse don’t remain and are subject to what?
Inactivation or reuptake
During reuptake of neurotransmitter, the presynpatic neuron takes up what?
Most of neurotranmitter molecules intact and reuses them.
What are special membrane proteins that facilitate reuptake?
Transporters
What is taken back up into presynaptic terminal?
Serotonin
What is broken down by acetylcholinesterase into acetate and choline?
Acetylcholine
Excess dopamine is converted into what?
Inactive chemicals
In what two ways is negative feedback in the brain accomplished?
Autoreceptors
Postsynaptic Neurons
What are the receptors that detect the amount of transmitter released and inhibit further synthesis and release?
Autoreceptors
What responds to stimulation by releasing chemicals that travel back to the presynaptic terminal where they inhibit further release?
Postsynaptic neurons
Electrical synapses are faster than what?
Chemical transmissions
What is the direct contact of the membrane of one neuron with the membrane of another?
Gap Junction
What occurs in both cells, resulting in the two neurons acting as if they were one?
Depolarization
What causes graded depolarization in post synaptic cell?
Excitatory Postsynaptic Potential (EPSP)
What causes graded HYPERpolarization in postsynaptic cell?
Inhibitory Postsynaptic Potential (IPSP)
What is the probability of action potential in a given neuron depending on the ratio of EPSP’s to IPSP’s at a given moment?
Summation
What is it called when signals from different locations arrive simultaneously?
Spatial Summation
What is it called when signals arrive in close time/
Temporal Summation
What increases the number of AP above the spontaneous firing rate?
EPSP’s
