Would you expect to find larger motor units in the postural muscles of the back or the muscles of the hand? Explain your answer.

A drug that blocks Na⁺ channels in neurons does so not only in the axon but also in the dendrites and cell body. What overall effect would this have on action potential generation?

​​What would happen if the drug blocked K⁺ channels instead?

Explain how an action potential is propagated down an axon in continuous conduction. Why is saltatory conduction faster than continuous conduction?

A hypothetical poison blocks K⁺ leak channels. How would this affect the resting membrane potential of skeletal muscle fibers? Explain your reasoning.

Explain why cardiac muscle cells and some smooth muscle cells will continue to contract even when their nerve supply has been removed

Explain what would happen if depolarization of the trigger zone led to a negative feedback loop instead of a positive one.

Albert, the patient in question 3, takes the drug lithium, which reduces the permeability of the neuronal axolemma to Na⁺ (that is, it allows fewer Na⁺ to enter the axon). Predict the effect this would normally have on his neuronal action potentials. Do you think this drug would be beneficial or harmful, considering his condition?

During a surgical procedure, an anesthesiologist administers to the patient an inhaled anesthetic agent that opens Cl⁻ channels in the postsynaptic membranes of neurons in the brain. Explain why this would put the patient 'to sleep' for the duration of the surgical procedure.

P​​redict the effect that tetrodotoxin would have on Albert's muscle fiber action potentials (see question 3). Would it affect end-plate potentials at the motor end plate? Why or why not?

The d​​rug neostigmine blocks the actions of acetylcholinesterase in the synaptic cleft. What effect would this have on synaptic transmission? What effects might you expect to see as a result of this drug?

Albert accidentally ingests the poison tetrodotoxin from the pufferfish, which you know blocks voltage-gated Na⁺ channels. Predict the symptoms Albert will experience from this poisoning.

Mark the following statements as true or false. If a statement is false, correct it to make a true statement.

The resting membrane potential refers to the voltage difference across the membranes of excitable cells at rest.

Mark the following statements as true or false. If a statement is false, correct it to make a true statement.

The concentration of Na⁺ is highest in the cytosol, and the concentration of K⁺ is highest in the extracellular fluid.

Mark the following statements as true or false. If a statement is false, correct it to make a true statement.

The Na⁺/K⁺ pumps and gated channels maintain the Na⁺ and K⁺ gradients necessary for action potentials to occur.

Mark the following statements as true or false. If a statement is false, correct it to make a true statement.

A depolarization is a change in membrane potential that makes the potential less negative.

Describe the three components of the neuromuscular junction.

The ________ is the period of time during which it is impossible to stimulate a neuron to have an action potential, whereas the ________ is the period of time during which a larger-than-normal stimulus is required to elicit an action potential.

Which of the following statements best describes saltatory conduction?

a. Every section of the axolemma must be depolarized and triggered to generate an action potential.

b. The internodes must generate action potentials.

c. The dendrites and cell bodies propagate EPSPs toward the trigger zone.

d. Only the nodes of Ranvier must generate action potentials.

Identify the following as properties of electrical synapses (ES), chemical synapses (CS), or both (B).           

a. ______ The plasma membranes of presynaptic and postsynaptic neurons are joined by gap junctions.          

b. ______ Transmission is unidirectional and delayed.          

c. ______ A presynaptic neuron and a postsynaptic neuron are involved.          

d. ______ The use of neurotransmitters packaged into synaptic vesicles is required.          

e. ______ Transmission is nearly instantaneous and bidirectional.

The trigger for exocytosis of synaptic vesicles from the presynaptic neuron is:

a. Arrival of an action potential at the axon terminal and influx of calcium ions.

b. Summation of IPSPs at the presynaptic neuron.

c. Binding of neurotransmitters to the axon hillock.

d. Influx of Na⁺ into the postsynaptic neuron.

Which of the following is not a method by which the effects of neurotransmitters are terminated?​​

a. Reuptake into the presynaptic neuron

b. Diffusion away from the synaptic cleft and uptake by glial cells

c. Movement back to the cell body by retrograde axonal transport

d. Degradation by enzymes in the synaptic cleft

A ________ is characterized by multiple input neurons synapsing on one postsynaptic neuron.

a. Diverging circuit

b. Discharge zone

c. Facilitation zone

d. Converging circuit

Mark the following statements as true or false. If a statement is false, correct it to make a true statement.

The Na⁺/K⁺ pumps and gated channels maintain the Na⁺ and K⁺ gradients necessary for action potentials to occur.

Mark the following statements as true or false. If a statement is false, correct it to make a true statement.

A depolarization is a change in membrane potential that makes the potential less negative.

Mark the following statements as true or false. If a statement is false, correct it to make a true statement.

A local potential is a change in membrane potential that conducts the long-distance signals of the nervous system.

Mark the following statements as true or false. If a statement if false, correct it to make a true statement.

Postsynaptic potentials may summate by spatial summation in which multiple neurons fire onto a single postsynaptic neuron.

Mark the following statements as true or false. If a statement if false, correct it to make a true statement.

An inhibitory postsynaptic potential causes the membrane potential of the postsynaptic neuron to approach threshold.