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True or False? Action potentials travel in only one direction down an axon because potassium channels in the neuron are refractory and cannot be activated for a short time after they open and close. |
FALSE |
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The membrane depolarizes above a certain threshold potential which triggers the creation of an ____. |
Action potential |
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What describes how a neuronal membrane’s potential is altered in the presence of inhibitory signals? |
Hyperpolarization |
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Where in the neuron do action potentials begin? |
Axon hillock |
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How is an action potential propagated down an axon after voltage-gated sodium channels open in a region of the neuron’s membrane? |
Sodium ions enter the neuron and diffuse to adjacent areas, resulting in the opening of voltage-gated sodium channels farther down the axon |
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What causes the release of the neurotransmitter molecules? |
An action potential reaching the end of the axon |
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The space between an axon of one neuron and the dendrite of another neuron is called a ____ |
Synaptic cleft |
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Neurons store neurotransmitter molecules in vesicles located within ____. |
Synaptic terminals |
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A type of cell that must have a receptor for the chemical signal. |
Target cell |
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A compound that is secreted in one part of the body and travels through the bloodstream to another part of the body where it has an effect is called a ____. |
Hormone |
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Protein signal molecules are not permeable to the cell membrane but can affect their target cells because: |
The target cells have cell membrane bound receptors specific to the signal molecule |
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In a normal cell: |
The membrane potential is negative |
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In a portal system how many capillary beds does the blood flow through as it travels from the heart back to the heart? |
2 |
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A neuron’s nucleus is located in its ____. |
Cell body |
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A nerve impulse moves toward a neuron’s cell body along ____. |
Dendrites |
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A never impulse moves away from a neuron’s cell body along ____. |
Axons |
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An impulse relayed along a myelinated axon "jumps" from ____ to ____. |
Node of Ranvier, Node of Ranvier |
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Axons insulated by a ____ are able to conduct impulses faster than those not so insulated. |
Myelin sheath |
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What type of cell makes up the myelin sheath of a motor neuron? |
Schwann cells |
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What part of a neuron relays signals from one neuron to another neuron or to an effector? |
Synaptic terminal |
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What describes the difference in electrical charge across a membrane? |
Membrane potential |
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Resting neurons are most permeable to which of the following ions? |
K+ |
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True or False? The potential energy of an membrane potential comes solely from the difference in electrical charge across the membrane. |
FALSE |
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Which channel is mainly responsible for the resting potential of a neuron? |
Potassium leak channel |
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Which term describes an electrical signal generated by neurons? |
Action potential |
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Which channel maintains the concentration gradients of ions across a neuronal membrane? |
The sodium-potassium pump moving Na+ ions out and K+ ions in |
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What behavior is observed if the voltage across a neuronal membrane is set to -20mV? |
The sodium channel opens, and the Na+ ions flow in |
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