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22 Cards in this Set
- Front
- Back
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When do the potassium gates open in an action potential?
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Essentially right when the voltage is peaking.
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When does the relative refractory period begin?
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Right around (a bit before?) when the voltage returns down to the threshold level.
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What is the effect of hypokalemia on the body in general? On the heart?
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It reduces excitability, leading towards paralysis. It causes cardiac arhythmias in the heart, which are deadly.
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What is the effect of hyperkalemia on the body in general? On the heart?
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It increases excitability of the neurons and myocytes. This causes cardiac arrest, which is deadly.
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What is TTX?
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The stuff in pufferfish, which blocks sodium channels.
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How does the body distinguish different types of sensory input, given that all action potentials are essentially the same?
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There are "labeled lines" which carry different inputs to different parts of the brain.
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What effect does a lack of ATP have on action potentials?
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With no ATP, sodium gates will not reactivate, and thus you cannot have another action potential.
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What is myelin formed from in the central nervous system? The peripheral nervous system?
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Oligodendrocytes and Schwann cells, respectively.
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What is the purpose of the Nodes of Ranvier in a myelinated cell?
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To provide a place for the action potential to be regenerated, since some of the signal is lost even in myelinated regions.
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In an electrical synapse, how many connexins are in a connexon? How many connexons in a gap junction?
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6 connexins = 1 connexon. 2 connexons = 1 gap junction.
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How do electrical synapses compare with chemical ones in terms of directionality and connection between pre- and post-synaptic cells?
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Electrical synapses are bidirectional; chemical ones only go one way. Electrical synapses also have a connection between the cytoplasms of the pre- and post-synaptic cells.
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What is an EPSC? An EPSP? How are they related? What do EPSP's do?
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An excitatory post-synaptic current; an excitatory post-synaptic potential. EPSC's lead to EPSP's, which can summate to create an action potential.
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In directly-gated channels, what ions or combinations of ions produce a excitatory response? An inhibitory response?
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Excitatory: Na+ alone & (Na+ and K+).
Inhibitory: K+ alone & Cl- alone. |
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How do directly-gated and indirectly-gated channels differ? (2 major ways)
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Directly-gated channels are faster, and the same molecule is the receptor and effector.
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What are some advantages of chemical synapses?
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They can use inhibitory inputs, they can use specific transmitters for specific responses, they allow for more complex signals, and they are more plastic in structure and function (they can be continually altered).
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How can a bunch of EPSPs reach the post-synaptic neuron at the same time to summate and create an action potential?
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There are thousands of other neurons providing input. As well, EPSPs usually last much longer than action potentials, so one neuron can have many of its EPSPs acting post-synaptically at one time.
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Where is the action potential initated? Why there?
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It is initiated at the axon hillock, because it has the lowest threshold level.
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What is the main excitatory neurotransmitter?
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Glutamate.
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What are the main inhibitory transmitters?
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GABA, glycine.
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What are some classes of neurotransmitters (besides excitatory and inhibitory)?
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Amines, peptides, purines, and gases.
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What is the name of the receptors that ATP stimulates? What type of signal do they pass on?
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They are called P2X3 receptors. They are transmitters of pain.
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What are some features of transmitter/receptor systems that are targeted by pharmaceuticals?
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Transmitter synthesis, transmitter release, receptor/ion channel properties, second messenger cascades, transmitter uptake or degradation systems, transmitters binding to multiple receptors (narrowed down to lessen side effects).
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