Exam 48: Neurons, Synapses, and Signaling

Why are action potentials usually conducted in one direction?

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 ________.

The Nernst equation specifies the equilibrium potential for a particular ion. This equilibrium potential is a function of ________.

In multiple sclerosis, the myelin sheaths around the axons of the brain and spinal cord are damaged and demyelination results. How does this disease manifest at the level of the action potential? I.Action potentials move in the opposite direction on the axon. II.Action potentials move more slowly along the axon. III.No action potentials are transmitted.

A graded hyperpolarization of a membrane can be induced by ________.

Use the information in the table to answer the question. Ion Extracellular concentration () Intracellular concentration () 300 50 40 350 Calculate the equilibrium potential for sodium. Assume a temperature of 37°C.

Opening all of the sodium channels on an otherwise typical neuron, with all other ion channels closed (which is an admittedly artificial setting), should move its membrane potential to ________.

After the depolarization phase of an action potential, the resting potential is restored by ________.

Tetrodotoxin blocks voltage-gated sodium channels, and ouabain blocks sodium-potassium pumps. If you added both tetrodotoxin and ouabain to a solution containing neural tissue, what responses would you expect?

Refer to the following graph of an action potential to answer the question. The neuronal membrane is at its resting potential at label ________.

At the neuromuscular junction, the neurotransmitter acetylcholine (ACh)is degraded by acetylcholinesterase. If a neurophysiologist applies the naturally occurring acetylcholinesterase inhibitor, onchidal (produced by the mollusc Onchidella binneyi), to a synapse, what would you expect to happen?

In a resting potential, an example of 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 ________.

The botulinum toxin, which causes botulism, reduces the synaptic release of ________.

Conduction and refractory periods (states)are typical of ________.

Neurotransmitters are released from axon terminals via ________.

Refer to the following graph of an action potential to answer the question. The membrane's permeability to sodium ions is greatest at label ________.

The activity of acetylcholine in a synapse is terminated by its ________.

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 membrane is also ________.

The operation of the sodium-potassium pump moves ________.

Which of the following ions is most likely to cross the plasma membrane of a resting neuron?