front 1 A simple nervous system | back 1 includes sensory information, an integrating center, and effectors. |
front 2 Most of the neurons in the human brain are | back 2 interneurons |
front 3 The nucleus and most of the organelles in a neuron are located in the | back 3 cell body |
front 4 The point of connection between two communicating neurons is called the | back 4 synapse |
front 5 In a simple synapse, neurotransmitter chemicals are released by | back 5 the presynaptic membrane |
front 6 Although the membrane of a "resting" neuron is highly permeable to potassium ions, its membrane potential does not exactly match the equilibrium potential for potassium because the neuronal me | back 6 slighty permeable to sodium ions |
front 7 The operation of the sodium-potassium "pump" moves | back 7 sodium ions out of the cell and potassium ions into the cell |
front 8 A cation that is more abundant as a solute in the cytosol of a neuron than it is in the interstitial fluid outside the neuron is | back 8 K+ |
front 9 The membrane potential that exactly offsets an ion's concentration gradient is called the | back 9 equilibrium postsynaptic potential |
front 10 ATP hydrolysis directly powers the movement of | back 10 Na+ out of cells |
front 11 Two fundamental concepts about the ion channels of a "resting" neuron are that the channels | back 11 open and close depending on stimuli, and are specific as to which ion can traverse them. |
front 12 Opening all of the sodium channels, with all other ion channels closed–which is an admittedly artificial setting–on an otherwise typical neuron should move its membrane potential to | back 12 +62 mV |
front 13 The "selectivity" of a particular ion channel refers to its | back 13 permitting passage only to a specific ion. |
front 14 For a neuron with an initial membrane potential at -70 mV, an increase in the movement of potassium ions out of that neuron's cytoplasm would result in the | back 14 hyperpolarization of the neuron. |
front 15 A graded hyperpolarization of a membrane can be induced by | back 15 increasing its membrane's permeability to K+. |
front 16 Self-propagation and refractory periods are typical of | back 16 action potentials |
front 17 The "threshold" potential of a membrane is the | back 17 minimum depolarization needed to operate the voltage-gated sodium and potassium channels |
front 18 Action potentials move along axons | back 18 more rapidly in myelinated than in nonmyelinated axons |
front 19 A toxin that binds specifically to voltage-gated sodium channels in axons would be expected to | back 19 prevent the depolarization phase of the action potential |
front 20 After the depolarization phase of an action potential, the resting potential is restored by | back 20 the opening of voltage-gated potassium channels and the closing of sodium channels. |
front 21 The "undershoot" phase of after-hyperpolarization is due to | back 21 sustained opening of voltage-gated potassium channels |
front 22 Immediately after an action potential passes along an axon, it is not possible to generate a second action potential; thus, we state that the membrane is briefly | back 22 refractory |
front 23 The fastest possible conduction velocity of action potentials is observed in | back 23 thick, myelinated neurons |
front 24 In the sequence of permeability changes for a complete action potential, the first of these events that occurs is the | back 24 opening of voltage-gated sodium channels |
front 25 Saltatory conduction is a term applied to | back 25 jumping from one node of Ranvier to the next in a myelinated neuron |
front 26 Two fundamental principles that characterize gated ion channels in the neuronal membrane are that the channels | back 26 open and close depending on stimuli and are specific as to which ion can traverse them. |