Chapter 11 Mastering: Electrophysiology and Neuronal Synapses

Batrachotoxin produced by certain species of frogs is a toxin that permanently opens voltage-gated Na ion channels. The results of exposure to batrachotoxin will be

inability to generate action potentials

Postsynaptic potentials are

local potentials

Saltatory propagation occurs in _________ axons, in which action potentials _________.

myelinated; move from one node of Ranvier to another

Action potential propagation in unmyelinated axons happens via

continuous conduction

Depolarization to threshold during action potential propagation in axons is due to

diffusion of Na ions down to the next segment of the axon

Loss of K ions from the cytosol will have the same effect as

gain of Cl ions

The channels that open when the axolemma reaches threshold depolarization are the

voltage-gated Na ion channels

The generation of an action potential in a neuron requires the presence what type of membrane channels?

voltage-gated channels

Which of these ions triggers exocytosis of synaptic vesicles?

Ca2+

During an action potential, hyperpolarization is caused by

K+ efflux

Which of the following events will cause an EPSP?

Na ions enter postsynaptic cell

Depolarizing local potentials are caused by an influx of

Na ions via gated ion channels

The relative refractory period is caused by

hyperpolarization

Which of the following is NOT one of the mechanisms for synaptic transmission termination?

Uptake of neurotransmitter into postsynaptic neuron

If a drug inhibits the enzyme Acetylcholinesterase, the effect will be

increased ACh availability in synaptic cleft

Nicotine is addictive because it causes dopamine-releasing neurons to fire more action potentials. Nicotine will therefore cause

increased levels of dopamine in the synaptic cleft

If a neuron simultaneously receives a stimulus that results in local depolarization of 10 mV and a stimulus that results in a local hyperpolarization of 10 mV, the net effect would be

no net change in membrane potential

If a drug inhibits neurotransmitter receptors on the postsynaptic cells

the neurotransmitter will have no effect in the postsynaptic cell