BIO 25

Which of the following best describes the role of calcium in synaptic activity?

Calcium influx into the synaptic terminal causes vesicle fusion with the plasma membrane and the release of neurotransmitter.

The neurotransmitter glutamate opens channels that are permeable to sodium ions. What effect does glutamate produce on a postsynaptic neuron?

EPSPs

What is the role of neurotransmitter at a chemical synapse?

Neurotransmitter binds to receptors on the postsynaptic cell membrane.

Certain details about Mr. Roosevelt's case call into question whether he really suffered from polio. The pathological features that Mr. Roosevelt experienced were much more characteristic of Guillain-Barré syndrome, an autoimmune disease that involves the demyelination of peripheral nerves. Which neuroglia cells form the myelin sheath of motor nerves?

Schwann cells

When you take a pain reliever, which of the following best describes, in general terms, how this affects the threshold of neurons?

Taking a pain reliever increases the threshold.

Female gymnasts can contort their bodies in many different ways and land on a 4" beam with accuracy. Which fiber type is responsible for this ability?

Type A fibers

What is the primary role of the enzyme acetylcholinesterase (AChE) at a cholinergic synapse?

What is the primary role of the enzyme acetylcholinesterase (AChE) at a cholinergic synapse?

What type of channel in the postsynaptic membrane binds neurotransmitter?

a chemically gated channel

Poliomyelitis is caused by a virus that spreads easily in human populations. Most people with polio infections show no symptoms of disease. However, in a small percentage of victims, the virus enters the central nervous system and attacks the motor neurons of the spinal cord. Motor neurons are an example of what type or class of neuron?

a multipolar neuron that has two or more dendrites and a single axon

Which of the following is an example of a presynaptic cell?

a neuron

Both poliomyelitis and Guillain-Barré syndrome can involve paralysis where control over skeletal muscle function is lost. What is the neurotransmitter that a motor neuron uses to communicate with a skeletal muscle?

acetylcholine

The mechanism by which the neurotransmitter is returned to a presynaptic neuron's axon terminal is specific for each neurotransmitter. Which of the following neurotransmitters is broken down by an enzyme before being returned?

acetylcholine

EPSPs and IPSPs summate at the __________.

axon hillock

The simplest level of information processing takes place at the __________.

axon hillock

Events that occur at a cholinergic synapse are listed here, but they are arranged in an incorrect order. Choose the correct order of these events below. (a) Calcium influx triggers exocytosis of ACh. (b) An action potential depolarizes the synaptic terminal. (c) ACh is removed by AChE. (d) ACh binds to receptors on the postsynaptic membrane.

b→ a→ d→ c

Which ion triggers synaptic vesicles to discharge neurotransmitter into the synaptic cleft?

calcium

Binding of a neurotransmitter to its receptors opens __________ channels on the __________ membrane.

chemically gated; postsynaptic

Binding of the neurotransmitter to its receptor causes the membrane to __________.

either depolarize or hyperpolarize

Which of these substances is considered a neuromodulator?

endorphins

What mechanism releases neurotransmitter from presynaptic neurons?

exocytosis

Compared to nerve action potentials, muscle action potentials do NOT have __________.

faster propagation

If EPSPs summate to a sustained value above threshold, then the initial segment will __________.

generate a string of action potentials

When neurotransmitter molecules bind to receptors in the plasma membrane of the receiving neuron,

ion channels in the plasma membrane of the receiving neuron open.

If a nerve cell receives many IPSPs in different locations at the same time, __________.

it will show spatial summation

A molecule that carries information across a synaptic cleft is a

neurotransmitter.

Which of these neurotransmitters does NOT bind to a plasma membrane receptor? serotonin GABA nitric oxide norepinephrine

nitric oxide

Which of these neurotransmitters is released at CNS adrenergic synapses?

norepinephrine

The neurotransmitter GABA blocks presynaptic voltage-gated calcium channels. Consequently, GABA produces __________.

presynaptic inhibition

In a synapse, neurotransmitters are stored in vesicles located in the __________.

presynaptic neuron

The effect of a nerve impulse on a postsynaptic neuron depends on the __________. quantity of neurotransmitter released characteristics of the receptor on the postsynaptic neuron kind of neurotransmitter released by the presynaptic neuron All of the listed responses are correct.

quantity of neurotransmitter released characteristics of the receptor on the postsynaptic neuron kind of neurotransmitter released by the presynaptic neuron All of the listed responses are correct.

Myelin limits the movement of ions across the axon membrane, so the action potential "jumps" from node to node along the axon. This is an example of what type of propagation?

saltatory

Compared to type A axons, type C axons are __________.

slower propagating unmyelinated smaller diameter All of the listed responses are correct.

What separates the presynaptic and postsynaptic cells at a chemical synapse?

synaptic cleft

The small space between the sending neuron and the receiving neuron is the

synaptic cleft.

If a signal from a sending neuron makes the receiving neuron more negative inside,

the receiving neuron is less likely to generate an action potential.

When calcium ions enter the synaptic terminal,

they cause vesicles containing neurotransmitter molecules to fuse to the plasma membrane of the sending neuron.

An action potential releases neurotransmitter from a neuron by opening which of the following channels?

voltage-gated Ca2+ channels

During propagation of the action potential, __________.

-local currents depolarize a -spot adjacent to the active zone -the axon hillock depolarizes the initial segment -after threshold is reached, sodium channels open rapidly -All of the listed responses are correct.