NEURO - CHAPTER 4 NEURAL CONDUCTION AND SYNAPTIC TRANSMISSION: HOW NEURONS SEND AND RECEIVE SIGNALS

"Reptilian stare" is sometimes used to describe the widely opened, unblinking eyes and motionless face of a. Parkinson's disease. b. multiple sclerosis. c. old age. d. infancy. e. Alzheimer's disease.

A

A change in the resting potential of a postsynaptic dendrite from -70 mV to -72 mV is called a. an IPSP. b. an EPSP. c. a depolarization. d. both A and C e. both B and C

A

A ligand of acetylcholine is a substance that a. binds to acetylcholine. b. stimulates acetylcholine's synthesis. c. facilitates acetylcholine's release. d. degrades acetylcholine. e. inhibits acetylcholine.

A

Action potentials are produced by the a. opening of voltage-activated sodium channels. b. closing of ligand-activated chloride channels. c. closing of ligand-activated potassium channels. d. opening of ligand-activated potassium channels. e. closing of voltage-activated calcium channels.

A

After release, most neurotransmitters are deactivated by a. reuptake. b. synaptic enzymes. c. the postsynaptic receptors. d. deactivating enzymes. e. ribosomes.

A

Both presynaptic facilitation and inhibition are mediated by a. axoaxonic synapses. b. axodendritic synapses. c. dendrodendritic synapses. d. axosomatic synapses. e. both A and D

A

Conduction of action potentials in myelinated axons a. is faster than in unmyelinated axons. b. is slower than in unmyelinated axons. c. is possible in only an antidromic direction. d. requires more energy than in unmyelinated axons. e. is always inhibitory.

A

Drugs that bind to a neurotransmitter's autoreceptors without activating them are usually a. agonists. b. antagonists. c. enzymes. d. endorphins. e. amino acids.

A

Drugs that block the reuptake of a neurotransmitter from the synapse are usually a. agonists of that neurotransmitter. b. antagonists of that neurotransmitter. c. enzymes of that neurotransmitter. d. receptor blockers. e. ligands of that neurotransmitter.

A

Endorphins are a. neuropeptides. b. monoamines. c. cholinergic. d. adrenergic. e. serotonergic.

A

In its resting state, a neuron is said to be a. polarized. b. depolarized. c. hypopolarized. d. hyperpolarized. e. firing.

A

In neurons without axons, conduction occurs entirely in the form of a. passive, decrementally conducted potentials. b. action potentials. c. all-or-none potentials. d. saltatory conduction. e. excitation.

A

Neurons do not normally fire more than 1,000 times per second because a. the absolute refractory period is typically about 1 millisecond. b. the relative refractory period is typically about 1 millisecond. c. the total refractory period is typically about 1 millisecond. d. the sodium-potassium pump cannot repolarize the cell in less than 1 millisecond. e. higher rates over excite the neuron.

A

Neurons without axons do not a. generate action potentials. b. exist. c. exist in mammals. d. exist in humans. e. produce inhibition.

A

Neuropeptides are synthesized in the cell body on a. ribosomes. b. the Golgi complex. c. vesicles. d. mitochondria. e. microtubules.

A

Neurotransmitter molecules are often packaged in vesicles by a. Golgi complexes. b. ribosomes. c. buttons. d. peptides. e. microtubules.

A

Some of the morphine-like substances that occur naturally in the brain are a. endorphins. b. autoreceptors. c. exogenous. d. benzodiazepines. e. false transmitters.

A

The end of the rising phase of an action potential occurs when the a. sodium channels close. b. sodium channels open. c. potassium channels open. d. potassium channels close. e. both A and D

A

The wave of absolute refractoriness that follows an action potential a. keeps the action potential from spreading actively back along an axon towards the cell body. b. increases the firing rate. c. increases the speed of axonal transmission. d. produces a second, negative action potential. e. produces saltatory conduction.

A

This drug is a muscarinic acetylcholine antagonist; it is an extract of the belladonna plant; and it has pupil-dilating effects: a. atropine. b. curare. c. morphine. d. opium. e. librium.

A

Which neurotransmitters are often released from string-of-beads axons? a. monoamines b. amino acids c. glutamate and GABA d. soluble gases e. peptides

A

Which of the following is NOT a monoamine? a. acetylcholine b. dopamine c. epinephrine d. serotonin e. norepinephrine

A

Which of the following is a cholinergic antagonist? a. curare b. Valium c. THC d. all of the above e. both B and C

A

With respect to neurotransmitters, which of the following is a correct sequence? a. synthesis, storage, exocytosis, reuptake b. reuptake, synthesis, deactivation, exocytosis c. deactivation, postsynaptic binding, synthesis, storage d. storage, deactivation, synthesis, exocytosis e. exocytosis, postsynaptic binding, synthesis, reuptake

A

APs are said to be all-or-none: This means that all APs a. are the same. b. in a particular neuron are the same. c. quickly or not at all. d. all of the above e. both A and C

B

Acetylcholine is a. a large-molecule neurotransmitter. b. synthesized by adding an acetyl group to a choline molecule. c. an indolamine. d. all of the above e. both B and C

B

After a neuron fires, the resting potential is re-established by the a. sodium-potassium pump. b. random movement of ions. c. refractory period. d. electrostatic gradient. e. EPSPs.

B

Autoreceptors of a neuron are sensitive to the neuron's own a. EPSPs. b. neurotransmitter. c. IPSPs. d. second messengers. e. APs.

B

Cocaine and amphetamines in high doses can produce a temporary disorder that is similar to a. epilepsy. b. schizophrenia. c. Parkinson's disease. d. paralysis. e. Huntington's disease.

B

Conduction of APs from the axon into the cell body and dendrites of a multipolar neuron is a. extremely rare. b. antidromic. c. orthodromic. d. both A and B e. both A and C

B

Drugs that facilitate the activity of the synapses of a particular neurotransmitter are said to be __________ of that neurotransmitter. a. facilitators b. agonists c. antagonists d. autoreceptors e. endorphins

B

Hyperpolarization is to depolarization as a. inhibitory is to excitatory. b. IPSPs are to EPSPs. c. APs are to IPSPs. d. APs are to EPSPs. e. many APs are to few APs.

B

In comparison to ionotropic receptors, metabotropic receptors generally produce a. their effects more rapidly. b. longer lasting effects. c. more localized effects. d. all of the above e. both A and C

B

Many buttons contain two sizes of vesicles; the larger ones typically contain a. small-molecule neurotransmitters. b. neuropeptides. c. acetylcholine. d. dopamine. e. glutamate.

B

Metabotropic receptors are linked to a. ligand-activated ion channels. b. signal proteins and G proteins. c. ionotropic receptors. d. vesicles. e. receptor subtypes.

B

Na+ ions are encouraged to move into neurons by a. nonrandom assignment. b. electrostatic pressure. c. the sodium-potassium pump. d. selective ion channels. e. nonrandom movement.

B

Neuropeptides are transported in vesicles from the cell body to the buttons at a speed of about a. 100 meters per minute. b. 40 centimeters per day. c. 60 meters per second. d. 40 meters per minute. e. 20 meters per second.

B

Once released, neurotransmitter molecules typically produce signals in postsynaptic neurons by a. binding to presynaptic receptors. b. binding to postsynaptic receptors. c. entering postsynaptic neurons. d. binding directly to calcium ions. e. attaching to vesicles.

B

Second messengers are formed in the a. presynaptic neuron. b. postsynaptic neuron. c. synaptic cleft. d. vesicles. e. mitochondria.

B

Technological developments led to the discovery of __________ throughout the mammalian brain; they seem to link the activities of inhibitory interneurons of the same type. a. neuropeptides b. gap junctions c. multipolar neurons d. chemical synapses e. G-proteins

B

The conduction of an action potential along any axon is mediated by the action of a. nodes of Ranvier. b. voltage-activated ion channels. c. ligand-activated ion channels. d. myelin. e. EPSPs.

B

The fact that the intensity of stimulation is related to the rate of neural firing is attributable to the a. absolute refractory period. b. relative refractory period. c. voltage gating in the buttons of the neuron. d. sodium-potassium pump. e. ligand gating in the buttons of the neuron.

B

The process of neurotransmitter release is referred to as a. excitation. b. exocytosis. c. synthesis. d. metabolism. e. expulsion.

B

The release of neurotransmitter molecules from buttons is often triggered by a. an efflux of sodium ions. b. an influx of calcium ions. c. the sodium-potassium pump. d. the arrival of an AP at the axon hillock. e. the release of calcium ions from the buttons.

B

There are three kinds of spatial summation and a. one kind of temporal summation. b. two kinds of temporal summation. c. three kinds of temporal summation. d. four kinds of temporal summation. e. no such thing as temporal summation.

B

There is only one neurotransmitter that is known to be deactivated in the synaptic cleft by enzymatic degradation; this neurotransmitter is a. dopamine. b. acetylcholine. c. acetylcholinesterase. d. norepinephrine. e. glutamate.

B

Which is considered to be the most prevalent excitatory neurotransmitter in the mammalian CNS? a. GABA b. glutamate c. dopamine d. acetylcholine e. none of the above

B

Which is considered to be the most prevalent inhibitory neurotransmitter in the mammalian CNS? a. glycine b. GABA c. glutamate d. serotonin e. dopamine

B

Which of the following are thought to play a role in reducing excessive neurotransmitter release? a. dendritic receptors b. autoreceptors c. dendritic spines d. postsynaptic receptors e. somatic receptors

B

A membrane potential is the difference in electrical charge between a. neuron membranes. b. synapses and cell bodies. c. the inside and outside of a cell. d. nuclei and tracts. e. ganglia and nerves.

C

According to the theory of Hodgkin and Huxley, a. Na+ ions continuously leak out of a resting neuron. b. Na+ ions are continuously pumped into a resting neuron. c. K+ ions continuously leak out of a resting neuron. d. K+ ions are continuously pumped out of a resting neuron. e. both A and B

C

Action potentials originate at the a. terminal buttons. b. synapses. c. axon initial segment, adjacent to the axon hillock. d. nodes of Ranvier. e. nucleus.

C

Active conduction is to passive conduction as a. IPSPs are to APs. b. EPSPs are to IPSPs. c. APs are to EPSPs. d. EPSPs are to APs. e. excitation is to inhibition.

C

Another word for "integration" is a. "firing." b. "all-or-none." c. "summation." d. "release." e. "activation."

C

Atropine is a. an extract of opium. b. a cholinergic agonist. c. a muscarinic antagonist. d. a pupil constrictor. e. a catecholamine.

C

Autoreceptors are commonly found in a. somas. b. postsynaptic membranes. c. presynaptic membranes. d. synaptic vesicles. e. ribosomes.

C

Axodendritic synapses a. are rare. b. often terminate on the axon hillock. c. always terminate on dendrites. d. sometimes terminate on cell bodies. e. A and C

C

By binding to nicotinic cholinergic receptors, this drug produces paralysis and death: a. atropine. b. chlordiazepoxide. c. curare. d. morphine. e. belladonna.

C

Cocaine and amphetamines are a. antischizophrenic drugs. b. used to treat Parkinson's disease. c. dopamine agonists. d. serotonin antagonists. e. dopamine antagonists.

C

Conduction of action potentials along an axon is a. instantaneous. b. decremental. c. nondecremental. d. entirely passive. e. always saltatory.

C

Contributing to the unequal distribution of ions on either side of a resting neural membrane a. is random ion movement. b. are electrostatic gradients. c. are sodium-potassium pumps. d. both A and B e. both B and C

C

Drugs that degrade vesicles and cause the neurotransmitter molecules to leak into the cytoplasm, where they are destroyed by enzymes, are a. receptor blockers. b. agonists of the neurotransmitter. c. antagonists of the neurotransmitter. d. autoreceptor blockers. e. amino acids.

C

How far do most postsynaptic potentials travel before they die out? a. to the axon hillock b. to the terminal buttons c. no more than a couple of millimeters d. about 50 millimeters e. both B and D

C

In the presence of the appropriate enzyme, dopamine is converted to a. L-dopa. b. tyrosine. c. norepinephrine. d. epinephrine. e. serotonin.

C

Ionotropic receptors are linked to a. ribosomes. b. neurotransmitters. c. ligand-activated ion channels. d. vesicles. e. G proteins.

C

Ions pass through the neural membrane via specialized pores called a. gap junctions. b. PSPs. c. ion channels. d. vesicles. e. connexons.

C

Many effective antischizophrenic drugs a. also are effective against Parkinson's disease. b. are D2 agonists. c. are D2 blockers. d. both A and B e. both A and C

C

Monoamines are divided into two groups: a. amino acids and peptides. b. peptides and proteins. c. catecholamines and indolamines. d. peptides and polypeptides. e. catecholamines and dopamine.

C

Neurotransmitters are often stored in a. aluminum foil. b. ribosomes. c. synaptic vesicles. d. nodes of Ranvier. e. the synaptic cleft.

C

Outside the membranes of resting neurons, there are many more a. inhibitory neurotransmitters. b. neurotransmitters. c. Na+ ions. d. K+ ions. e. nuclei.

C

Peptide neurotransmitters (i.e., neuropeptides) are synthesized in the cell body and a. stored in the Golgi complex until they are broken down. b. released by the Golgi complex into the synapse. c. transported in vesicles along microtubules to the buttons. d. stored in ribosomes with small-molecule neurotransmitters. e. transported along the axons to the nodes of Ranvier.

C

Serotonin is synthesized from a. tyrosine. b. L-dopa. c. tryptophan. d. norepinephrine. e. epinephrine.

C

Sodium-potassium pumps are a. integrators. b. refractory. c. transporters. d. excitatory. e. inhibitory.

C

The brief period of time immediately after the initiation of an action potential, when it is absolutely impossible to initiate another one in the same neuron, is called the a. threshold of excitation. b. threshold of inhibition. c. absolute refractory period. d. IPSP. e. relative refractory period.

C

Which of the following are synthesized from tyrosine? a. monoamines b. indolamines c. catecholamines d. amino acids e. both A and B

C

Which of the following is an endocannabinoid neurotransmitter? a. nitric oxide b. aspartate c. anandamide d. THC e. indolamine

C

Which of the following is synthesized directly from tyrosine? a. dopamine b. epinephrine c. L-dopa d. serotonin e. GABA

C

A neuron normally fires when a. its sodium-potassium pumps are stimulated. b. there is an EPSP. c. there is an IPSP. d. the degree of depolarization on the axon adjacent to the hillock exceeds the threshold of excitation. e. its buttons are stimulated.

D

About how many neuropeptides are currently classified by most experts as neurotransmitters? a. 2 b. 4 c. 9 d. just over 100 e. almost 3,000

D

Botox is a. a deadly poison. b. used to reduce tremors. c. a nicotinic antagonist. d. all of the above e. none of the above

D

In large myelinated human motor neurons, impulses travel at about a. the speed of light. b. 186,000 miles per second. c. 1 meter per second. d. 60 meters per second. e. 100 meters per second.

D

Na+ ions are continuously forced into neurons by a. their high internal concentration. b. their high external concentration. c. the negative resting potential. d. both B and C e. none of the above

D

Neurons recycle a. neurotransmitter molecules that have been drawn back into the terminal buttons after being released. b. the breakdown products of neurotransmitter molecules that have been degraded in the synapse by enzymes. c. vesicles that have been integrated into the button membrane during exocytosis. d. all of the above e. none of the above

D

Nitric oxide a. is a soluble gas neurotransmitter. b. is considered to be an unconventional neurotransmitter. c. participates in retrograde synaptic transmission. d. all of the above e. both A and B

D

Nondirected synapses a. involve the release of neurotransmitter molecules diffusely into the extracellular fluid. b. include string-of-beads synapses. c. involve the movement of neurotransmitter molecules across gap junctions. d. both A and B e. both B and C

D

Opioids play a role in a. analgesia. b. pleasure. c. retrograde transport. d. both A and B e. both B and C

D

Peptide neurotransmitters are a. synthesized in the cell body. b. amino acid chains. c. large-molecule neurotransmitters. d. all of the above e. both B and C

D

Salts in solution separate into positively and negatively charged a. membrane potentials. b. EPSPs. c. IPSPs. d. ions. e. crystals.

D

The abbreviation 5-HT stands for a. serotonin. b. dopamine. c. acetylcholine. d. both A and B e. none of the above

D

The one enzyme whose function is to deactivate a specific neurotransmitter once it has been released into the synapse is a. dopamine. b. L-dopa. c. acetylcholine. d. acetylcholinesterase. e. a G protein.

D

The receptors of the neuromuscular junction are a. cholinergic. b. nicotinic. c. muscarinic. d. both A and B e. both A and C

D

The tips of intracellular recording electrodes are a. about the size of a neuron. b. too small to be seen with the naked eye. c. less than one thousandth of a millimeter in diameter. d. both B and C e. none of the above

D

When a small-molecule neurotransmitter molecule binds to an ionotropic receptor, the a. cell fires. b. cell stops firing. c. ligand is deactivated. d. associated ion channel opens or closes. e. EPSP gradually increases.

D

Which drug was extracted from the belladonna plant and used by the ancient Greeks for cosmetic purposes? a. opium b. diazepam c. d-tubocurare d. atropine e. endorphin

D

Which of the following are membrane potentials? a. EPSPs b. IPSPs c. APs d. all of the above e. both A and B

D

Which of the following is NOT an amino acid neurotransmitter? a. aspartate b. glutamate c. glycine d. indolamine e. GABA

D

Which of the following is NOT found in neurons that release norepinephrine? a. dopamine b. L-dopa c. norepinephrine d. epinephrine e. tyrosine

D

Which of the following is a passive force that acts to encourage Na+ ions to enter resting neurons? a. random motion, which tends to move ions down their concentration gradients b. electrostatic pressure, which forces ions down their electrostatic gradients c. sodium-potassium pumps, which distribute Na+ and K+ ions equally d. both A and B e. both A and C

D

Acetylcholine is created by the addition of an acetyl group to a. a monoamine. b. a soluble gas. c. tryptophan. d. an indolamine. e. a choline molecule.

E

Action potentials can be conducted a. actively. b. passively. c. orthodromically. d. antidromically. e.all of the above

E

Adrenergic neurons release a. serotonin. b. norepinephrine. c. dopamine. d. acetylcholine. e. epinephrine.

E

After release, neurotransmitters are deactivated in the synapse by a. reuptake. b. enzymatic degradation. c. G proteins. d. all of the above e. both A or B

E

At rest, a. a neuron has a membrane potential of about -70 mV. b. the electrical charge outside the neuron is 70 mV less than inside the neuron. c. a neuron is polarized. d. all of the above e.both A and C

E

Dopamine is not an effective treatment for Parkinson's disease because a. dopaminergic neurons are restricted to the PNS. b. Parkinson's disease is a cholinergic dysfunction. c. Parkinson's disease is a noradrenergic dysfunction. d. d'Orta is the treatment of choice. e. dopamine does not readily penetrate the blood-brain barrier.

E

Drugs that bind to a neurotransmitter's receptors on the postsynaptic membrane without activating them are a. receptor blockers. b. agonists of the neurotransmitter. c. antagonists of the neurotransmitter. d. both A and B e. both A and C

E

During an action potential, the change in membrane potential associated with the influx of sodium ions triggers the a. opening of sodium channels. b. closing of chloride channels. c. opening of chloride channels. d. closing of potassium channels. e. opening of potassium channels.

E

EPSPs are a. graded responses. b. postsynaptic responses. c. transmitted decrementally. d. depolarizations. e. all of the above

E

Glial cells have been shown to a. release chemical transmitters. b. contain receptors for neurotransmitters. c. conduct signals. d. influence synaptic transmission. e. all of the above

E

Glycine, aspartate, and glutamate are a. amino acid neurotransmitters. b. small-molecule neurotransmitters. c. transmitters at fast-acting, directed synapses. d. building blocks of proteins. e. all of the above

E

IPSP is to EPSP as a. graded is to nongraded. b. excitatory is to inhibitory. c. cable properties are to noncable properties. d. presynaptic is to postsynaptic. e. hyperpolarization is to depolarization.

E

In comparison to ionotropic receptors, metabotropic receptors a. are more prevalent. b. produce longer lasting effects. c. produce effects that are more diffuse. d. produce effects that take longer to develop. e. all of the above

E

In comparison to metabotropic receptors, ionotropic receptors produce effects that a. are less diffuse. b. develop more rapidly. c. are more enduring. d. all of the above e. both A and B

E

Many neurons contain and release two neurotransmitters. This situation is called a. covalence. b. ionotropism. c. cohabitation. d. metabotropism. e. coexistence.

E

Parkinson's disease is treated with a. dopamine. b. serotonin. c. acetylcholine. d. norepinephrine. e. L-dopa.

E

Prevalent in the cytoplasm of most terminal buttons are a. nuclei. b. mitochondria. c. synaptic vesicles. d. all of the above e. both B and C

E

Second messengers can a. be synthesized in response to activation of metabotropic receptors. b. influence metabolic activities of the cell. c. induce IPSPs or EPSPs. d. bind to DNA to influence protein synthesis. e. all of the above

E

Sodium-potassium pumps maintain the resting membrane potential by transporting a. Na+ ions into neurons. b. K+ ions into neurons. c. Na+ ions out of neurons. d. both A and B e. both B and C

E

Soluble-gas neurotransmitters a. are synthesized in the neural cytoplasm. b. once synthesized, immediately diffuse through the cell membrane into the extracellular fluid and into nearby cells. c. diffuse into target cells through their cell membranes. d. once in other cells, stimulate the synthesis of a second messenger and are immediately broken down. e. all of the above

E

The transmission of postsynaptic potentials is a. active. b. decremental. c. extremely rapid. d. all of the above e. both B and C

E

Vesicles travel from the cell body to the buttons a. on action potentials. b. along microtubules. c. at a rate of about 40 centimeters per second. d. at a rate of about 40 centimeters per day. e. both B and D

E

Which of the following are considered to be small-molecule neurotransmitters? a. neuropeptide transmitters b. monoamine neurotransmitters c. amino acid neurotransmitters d. both A and B e. both B and C

E

Which of the following is a nicotinic antagonist? a. Botox b. curare c. atropine d. all of the above e. both A and B

E

Which of the following is currently thought to be a valid general principle of synaptic transmission? a. Each neuron releases only one neurotransmitter. b. Each neurotransmitter acts on only one receptor subtype. c. All receptors are in postsynaptic membranes. d. All neurotransmitters are released into the synaptic cleft. e. none of the above

E

With respect to the maximum speed of axonal conduction in motor neurons, cats are to humans as a. 50 is to 100 meters per second. b. 80 is to 100 meters per second. c. 25 is to 100 meters per second. d. 82 is to 100 meters per second. e. 100 is to 60 meters per second.

E