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?

Why must a cell body be intact for an axon to regenerate? (Hint: What structure is housed only in the cell body, and what are its functions?)

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

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?

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.

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.

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?

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?

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

Which of the following statements about the general functions of the nervous system is false?

a. The three primary functions of the nervous system include sensory, integrative, and motor functions.

b. The integrative functions of the nervous system are its processing functions.

c. Sensory stimuli are transmitted on sensory efferent fibers to a sensory receptor.

d. Motor functions are carried out by fibers that carry signals to an effector.

Regulation of heart rate, blood pressure, and digestive functions is carried out by the:

a. Somatic motor division of the peripheral nervous system.

b. Central nervous system.

c. Visceral sensory division of the peripheral nervous system.

d. Autonomic nervous system.

Match each type of neuroglial cell with its correct function.

____ Schwann cells    ​​​​

____ Ependymal cells     

____ Microglial cells    ​​​​

____ Oligodendrocytes     

____ Satellite cells    ​​​​

____ Astrocytes

a. Phagocytic cells of the CNS

b. Surround the cell bodies of neurons in the PNS

c. Create the myelin sheath in the PNS

d. Anchor neurons and blood vessels, maintain extracellular environment around neurons, assist in repair of damaged brain tissue

e. Create the myelin sheath in the CNS

f. Ciliated cells in the CNS that produce and circulate the fluid around the brain and spinal cord

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

Aggregates of Golgi apparatus and lysosomes form dark-staining Nissl bodies within the cell body.

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

The axon contains a high density of ribosomes, rough endoplasmic reticulum, and Golgi apparatus.

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

Axons arise from the axon hillock.

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

Substances can move toward or away from the cell body through the axon via fast axonal transport.

An axon is best defined as a process that:

a. Transmits signals only toward the cell body.

b. Can generate action potentials.

c. Transmits signals only away from the cell body.

d. Cannot generate action potentials

The myelinated segment of an axon that is covered by a glial cell is called a/an ________; the gaps between glial cells where the axolemma is exposed are called ________.

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.

Match the following neurotransmitters with their correct description.    ​​​​

_____ GABA    ​​​​

_____ Dopamine     

_____ Substance P     

_____ Acetylcholine    ​​​​

_____ Glutamate     

_____ Endorphins     

_____ Norepinephrine

a. Neuropeptide involved in transmission of pain

b. Neurotransmitter released at the neuromuscular junction

c. Major excitatory neurotransmitter in the brain

d. Major inhibitory neurotransmitter in the brain

e. Neuropeptide involved in relief of pain

f. Catecholamine involved in the autonomic nervous system

g. Catecholamine involved in movement and behavior

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.