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
