neurophysiology 3&4 Flashcards
What causes the release of neurotransmitters at pre-synaptic membranes?
Influx of Ca2+ ions.
How are ionotropic and metabotropic receptors different?
Ionotropic: ligand-gated channel where binding of neurotransmitter results in a direct opening or closing of an ion channel. Induced response is fast but short-spread.
Metabotropic: G-protein coupled channel where binding of neurotransmitter results in a cascade of signaling events involving G Proteins and secondary molecules, all of which results in the opening or closing of an ion channel. Induced response is slow but widespread.
What system(s) is acetylcholine found in?
Peripheral Nervous System:
1. autonomic
2. somatic (neuromuscular//movement)
What are the two types of receptors of acetylcholine, and what type of response(s) does each induce?
- Nicotinic- ionotropic receptor, excitatory
- Muscarinic- metabotropic receptor, excitatory or inhibitory (CNS)
What system(s) is glutamate found in?
CNS (and is a major excitatory neurotransmitter in post-synaptic potentials)
What system(s) is Gamma Aminobutyric Acid (GABA) found in?
CNS (and is a major inhibitory neurotransmitter in post-synaptic potentials)
What GABA ion channel has an ionotropic receptor?
Cl- ion channel (hyperpolarization//inhibitory)
What are the names of the 3 catecholamine neurotransmitters? What system(s) do they function in? What receptor type(s) do they have?
Epinephrine and norepinephrine:
- Function in the CNS and the autonomic nervous system (in sympathetic)
Dopamine
- CNS only
ALL 3 have metabotropic receptors only.
What system(s) does serotonin function in? What receptor type(s) does it have?
Functions in the CNS (regulates mood/behavior)
Both ionotropic and metabotropic receptors
What system(s) do endogenous opioids function in?
Function in the CNS and PNS
How do the neuropeptides (endogenous opioid) endorphins block pain signals?
By modulating neurotransmitter release by competing at metabotropic receptors (e.g., Mu receptor)
How are the locations and mechanisms of synthesis different for neuropeptides versus small-molecule neurotransmitters?
Neuropeptides: protein synthesis in the soma
Small-molecule neurotransmitters: enzymatic activity in the axon terminal
How are endogenous opioids like endorphins synthesized?
the neuropeptide chain of the endogenous opioid is formed when its DNA is transcribed into mRNA in the nucleus, and then translated into protein by tRNA in the ribosome
How are neuropeptides (endogenous opioids) packaged differently from other neurotransmitters?
Neuropeptides: packaged into membrane-bound vesicles in the Golgi Apparatus in the soma, and then transported down to the axon terminal.
Small-molecule neurotransmitters: [empty] synaptic membrane-bound vesicles are made in the Golgi Apparatus in the soma, and then transported down to the axon terminal where the neurotransmitter is moved into the vesicle via a transporter molecule and the presence of Ca2+.
What activates the release of a neurotransmitter into a synaptic cleft?
Depolarization of neuron arrives at axon terminal –> voltage-dependent Ca2+ channel opens –> influx of Ca2+ into terminal occurs and signals release of neurotransmitter into synaptic cleft
