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12 Cards in this Set
- Front
- Back
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What are some key differences between the NMJ synapse and the synapse that occurs between the presynaptic neuron and the motor neuron in the spinal cord?
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1.) CNS doesn’t use ACh for excitation (uses glutamate instead).
2.) EPSP in the CNS is usually sub-threshold (around 1 mV), so integration of many presynaptic neurons is needed to stimulate a motor neuron above threshold (summation). (Whereas NMJ is a 1:1 ratio.) 3.) Synapse can be excitatory OR inhibitory in CNS. EPSPs depolarize the cell, IPSPs hyperpolarize the cell. (The NMJ only has LARGE, excitatory EPSPs.) |
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Excitation in the PNS uses _______ transmitters and _______ receptors.
Excitation in the CNS uses _______ transmitters and _______ receptors. Inhibition in the CNS uses _____ or ________ transmitters. |
ACh
Nicotinic ACh Glutamate Glutamate GABA Glycine |
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_______ and _______ receptors, which have an ________ function in the _____, are structurally homologous to ACh receptors, which have an _________ function in the _____. Meanwhile, ________ receptors are structurally very different from ACh receptors, even though they have a similar _______ function.
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GABA
Glycine Inhibitory CNS Excitatory NMJ Glutamate Excitatory |
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What is familial startle syndrome and what is its cause?
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Someone with familial startle syndrome will have hyperekplexia -- an exaggerated response to being startled that includes extreme muscle stiffness that often causes the person to fall down. A mutation in the glycine receptor will cause this.
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How do IPSPs work and why are they useful? What is the equation for inhibitory currents? What does the magnitude of the IPSP depend on.
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Inhibitory Postsynaptic Potentials hyperpolarize the cell by allowing an influx of Cl- ions. GABA or glycine act on ionotropic receptors that contain Cl- channels. The inhibition mechanism will often work on the muscle group that’s antagonistic to the one being excited. It is useful, for example, in the knee-jerk reflex because it allows flexors and extensors to work separately.
Same as the EPSP → magnitude of the current depends on the magnitude of conductance. Same equation: I(IPSP) = g(IPSP) x [V(m) – E(IPSP)] |
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GABA and glycine receptors are ____amers, structurally similar to _____ receptors.
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Pent(amers)
ACh |
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The NMJ has ____(large or small)____, _____(excitatory or inhibitory)_____ EPSPs, while the CNS has ____(large or small)____, ____(excitatory or inhibitory)_____ EPSPs.
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Large
Excitatory Small BOTH!! |
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What does GABA stand for? What does it do?
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Gamma amino butyric acid. It’s an inhibitory transmitter released in the CNS.
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ACh, GABA, and Glycine receptors are structurally homologous. What is the subunit situation for each?
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All are pentamers
ACh has 2 alpha, 1 beta, 1 gamma, 1 delta GABA has 2 alpha, 2 beta, 1 gamma Glycine has 3 alpha, 2 beta |
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Which receptor is important for inhibitory drug purposes? List 4 of these drugs. What do they do?
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GABA receptors bind to barbiturates, benzodiazepines, alcohol, and general anesthetics. They keep the Cl- channels open.
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Glutamate receptors are ____(slow or fast)______, _____(excitatory or inhibitory)____ receptors in the CNS. They are in a totally different receptor gene family than GABA, glycine or ACh. Describe their structure.
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Fast
Excitatory Tetrameric, have 3 transmembrane segments and a large extracellular binding site |
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V(m) for a motor neuron is _____ mV
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-65 mV
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