Neurotransmitters and Synaptic Transmission Flashcards
Electrical synapses
Two neurons are connected by a gap junction, which allows electrical current to flow directly from one cell to the other through open fluid channels. Ex. smooth muscle, cardiac muscle
Chemical synapses
Release NTs from presynaptic membrane and bind to receptors on postsynaptic membranes. Ex. CNS
T or F. Axon terminals can synapse with any part of the target neuron dendrites/cell bodies/or axons?
True
Small molecule neurotransmitters, give examples and where they are formed in the cell?
Acetylcholine and ATP/Adenosine
Glutamate (Excitatory)
GABA/Glycine (Inhibitory)
Serotonin (Inhibitor of pain, control of mood, sleep)
Histamine/Dopamine/Norepinephrine/Epinephrine
Small molecules are formed in the terminal of a neuron
What are some examples of protein/peptide NT? Where are they formed?
Hypothalumus control -> Thyrotropin-releasing hormone, luteinizing hormone releasing hormone, somatostatin
Pituitary control -> Adrenocorticotropic hormone, prolactin, leuteinizing hormone, thyrotropin, growth hormone, vasopressin, oxytocin
Endorphins -> enkephalins, opioids
Others -> Substance P, Bradykinin, Angiotensin II
Peptides are made in the cell body
Transmitter-gated ion channels
Ionotropic receptors -> ion channels, change shape when NT binds, direct effect. General anesthetics primarily act by either enhancing inhibitory signals or by blocking excitatory signals.
G-protein-coupled receptors -> Indirectly, second messenger pathway, slow
An activated G-protein diffuses in the membrane to act on its target, which may be an ion channel, enzymes, or gene transcription.
Metabotropic receptors
General overview of NT action
- Reuptake 2. Breakdown 3. Diffusion
How does cocaine work?
Binds to dopamine reuptake receptor and inhibits it, thus more dopamine remains in synaptic cleft -> leading to more pleasurable effects
How does ecstacy work?
Binds to serotonin receptors, more serotonin ends up in the synaptic space preventing the reuptake back into the terminal and can bring more serotonin from the terminal into the synaptic space
How does the potentiation of synapses lead to memory formation?
The increase in glutamate release causes increased conduction in postsynaptic neuron by binding to AMPA receptors. This leads to long lasting potentiation of synapse, more its activated = more memory
How does hypercalcemia affect neuronal modulation?
The high levels of calcium ions decrease the neuron membrane permeability to sodium ions, thus decreasing excitability
How does hypocalcemia affect neuronal modulation?
Hypocalcemia therefore INCREASES neuronal excitability, causing neuromuscular irritability and muscle spasms.
