Synapses and Neurotransmission Flashcards
What neurotransmitter is released from the axon terminal of a neuron when it activates a muscle cell?
ACh
What type of ACh receptor does ACh bind to on the postsynaptic side when a neuron stimulates a muscle?
nicotinic
What enzyme is responsible for the enzymatic degradation of ACh?
acetylcholinesterase
What are 3 pathways for removal of a neurotransmitter from the synaptic cleft?
enzymatic degradation
reuptake
diffusion
How is dopamine, NE, and serotonin removed from the synaptic cleft?
reuptake (mono-amine oxidase also enzymatically breaks it down within the terminal)
How is glutamate removed from the synaptic cleft?
diffusion- into glial cells
What two molecules does acetylcholinesterase break down ACh into?
choline and acetate
Where does choline move back to?
presynaptic neuron
What two molecules can be reassembled to form acetylcholine
acetyl CoA and choline
This disease is an autoimmune disease that causes the immune system to attack nicotinic ACh receptors
Myasthenia gravis
How does myasthenia gravis cause weakness?
There is a lack of ACh receptors to receive the ACh
How does pyridostigmine improve strength?
inhibits the enzyme that breaks down ACh so it’s left in the synaptic cleft longer
_________ serve to bring the membrane closer to threshold for generating an AP
excitatory postsynaptic potential (EPSP)
____________ make the cell’s membrane potential more negative, making it harder to generate an AP
inhibitory postsynaptic potential (IPSP)
What neurotransmitter classification is ACh?
choline ester
What are the 3 catecholamines
dopamine, NE, epinephrine
What is the pathway of the 5 molecules involved in catecholamine synthesis
tyrosine–> L-dopa—> dopamine—-> NE—-> epinephrine
True or false: there is no dopamine B-hydroxylase in a dopamine neuron
true, that enzyme leads to the production of NE
Is there dopamine in an epinephrine cell?
yes, somewhere there has to be since it is a precursor of epinephrine
This catecholamine is involved in movement as well as the reward pathway
dopamine
This is a movement disorder that involves the loss of dopamine-releasing neurons in the substantia nigra in the basal ganglia
Parkinson’s disease
What drug is used to treat Parkinson’s disease?
L-dopa, it passes through BBB
Why is L-dopa often given with deprenyl?
deprenyl prevents the breakdown of L-dopa by blocking MAO-B (monoamine oxidase)
Is Epi a neurotransmitter or a hormone?
Mainly a hormone, it is released into the blood
is NE a neurotransmitter or a hormone?
can act as both
What does G protein coupled mean?
if a ligand binds on the outside of the cell, it will have an effect on the inside of the cell
What type of receptors are adrenergic receptors?
G protein coupled and linked to second messenger signal pathways
This adrenergic receptor is mainly responsible for blood vessels; it causes vasoconstriction and increases BP
A1
This adrenergic receptor is responsible for tachycardia, increased myocardial contractility, and increased lipolysis
B1
This adrenergic receptor is responsible for bronchodilation
B2
This adrenergic receptor presynaptic and is mostly regulatory. It inhibits NE release, ACh release, and insulin release
A2
______ __________ are drugs that increase the levels of catecholamins
MAO inhibitors
what is serotonin made from?
tryptophan
This prevents the reuptake of serotonin into the presynaptic terminal which leaves it in the synapse for a longer period of time
SSRIs (selective serotonin reuptake inhibitors)
What are 2 large functions of serotonin?
regulating sleep
regulating emotion
What is the main excitatory a.a. neurotransmitter?
glutamate
What is the main inhibitory a.a. neurotransmitter?
GABA
What are the 2 types of glutamate receptors
metabotropic- more complicated
ionotropic- ion channels
When glutamate binds to _______, it opens a Na+ channel and causes depolarization
AMPA
______ acts as a Ca2+ blocker
Mg
What type of receptor releases Mg when glutamate binds, which allows Ca2+ to rush in
NMDA
What is GABA made from?
glutamate
This type of GABA opens a Cl- channel which leads to hyperpolarization
GABAa
This type of GABA receptor opens a K+ channel
GABAb (*remember, K+ will move out of the cell)
This is released by afferent neurons that relay sensory information into the CNS, especially indicates damage and pain
substance P
