Chapter 7

In a myelinated axon, Na+ channels are A. along the whole length of the axon. B. every 5 mm. C. concentrated at the nodes of Ranvier. D. less numerous at the nodes of Ranvier.

C. concentrated at the nodes of Ranvier.

Which type of cell lines the ventricles of the brain and help produce cerebrospinal fluid? A. microglia B. satellite cells C. ependymal cells D. oligodendrocytes

C. ependymal cells

What structure is found around PNS axons that is NOT found around CNS axons? A. nodes of Ranvier B. myelin sheath C. neurilemma D. plasma membrane

C. neurilemma

Chemicals that stimulate action potentials in postsynaptic cells are called A. hormones. B. enzymes. C. neurotransmitters. D. neurotrophins

C. neurotransmitters.

Fetal neuron growth requires the actions of a group of chemicals known as A. endorphins. B. synapsins. C. neurotrophins. D. glutamates.

C. neurotrophins.

Which of the following is true of axons? A. contain receptive areas B. very thin and short C. originates at the axon hillock on the cell body D. transmits graded electrochemical impulses

C. originates at the axon hillock on the cell body

Which ion's movements is responsible for repolarization? A. influx of K+ B. influx of Na+ C. outward diffusion of K+ D. outward diffusion of Na+

C. outward diffusion of K+

The ability of a neuron to transmit charge through its cytoplasm is called cable properties and is very A. good. B. strong. C. poor. D. easy.

C. poor.

The membrane of resting nerve cells is more permeable to ____________ ions than ____________ ions. A. sodium, potassium B. calcium, potassium C. potassium, sodium D. chloride, potassium

C. potassium, sodium

As the intensity of a stimulus increases, more axons will become activated. This process is called A. threshold. B. refraction. C. recruitment. D. None apply.

C. recruitment.

Cells supporting neuron cell bodies in ganglia are termed A. astrocytes. B. ependymal cells. C. satellite cells. D. Schwann cells

C. satellite cells.

A lack of extracellular Ca2+ would cause increased release of neurotransmitters.

FALSE

During the absolute refractory period, a supramaximal stimulus can bring the cell to threshold.

FALSE

Electrical synapses are functionally linked by tight junctions.

FALSE

Excitable cells are incapable of maintaining a constant resting membrane potential.

FALSE

Most synapses in the body are electrical.

FALSE

Nerve cells depolarize due to the influx of K+.

FALSE

T/F A nerve is a bundle of axons in the CNS

FALSE

T/F All axons in the PNS have a myelin sheath.

FALSE

T/F An inactivated ion channel will respond to a strong stimulus.

FALSE

T/F Anterograde transport uses dynein molecular motor proteins.

FALSE

T/F Axonal transport from the cell body to the dendrites and axon is retrograde transport.

FALSE

T/F Axons require ATP to produce an action potential.

FALSE

T/F Both neurons and neuroglia will easily divide by mitosis.

FALSE

T/F Destruction of astrocytes would decrease the rate at which action potentials are transmitted.

FALSE

T/F Glial cells normally lose their mitotic ability prior to birth.

FALSE

T/F Most brain tumors in adults are found within neurons.

FALSE

T/F Sensory nerves cause muscle contraction

FALSE

T/F Somatic motor neurons innervate involuntary effectors.

FALSE

T/F The blood-brain barrier prevents hydrophobic molecules from diffusing into the brain.

FALSE

T/F The greater the number of depolarization regions on an axon, the faster the action potential will be conducted.

FALSE

T/F The nerve is the basic structural and functional unit of the nervous system.

FALSE

The average resting membrane potential of a neuron is -85mV.

FALSE

Action potentials frequency encodes stimulus intensity.

TRUE

All axons in the PNS are surrounded by Schwann cells.

TRUE

All cells have a membrane potential.

TRUE

Cells become more negative during hyperpolarization.

TRUE

Neurotransmitter release can be inhibited by damaging the SNARE complex.

TRUE

Neurotransmitter release from synaptic vesicles is caused by Ca2+-synaptotagmin complex interruption of the SNARE complex.

TRUE

T/F Astrocytes can be excited by changes in intracellular Ca2+ concentration.

TRUE

T/F Both depolarization and repolarization are produced by the diffusion of ions down their concentration gradient.

TRUE

T/F Conduction without decrement means that action potentials transmitted down an axon will not decrease in amplitude.

TRUE

T/F Ganglia are clusters of nerve cell bodies located in the peripheral nervous system.

TRUE

T/F Most motor neurons are multipolar.

TRUE

T/F Myelinated axons transmit action potentials more rapidly than unmyelinated axons.

TRUE

T/F Retrograde axonal transport may be responsible for movement of herpes virus, rabies virus, and tetanus toxin from nerve terminals to the cell body.

TRUE

T/F Schwann cells and oligodendrocytes have similar functions.

TRUE

T/F Sensory neurons for muscle position are the fastest conducting neurons.

TRUE

The blood-brain barrier may prevent medications from reaching brain tissue.

TRUE

______ synapses occur between axons of presynaptic cells and dendrites of postynaptic cells. A. Axodendritic B. Axosomatic C. Myoneural D. Axoaxonic

A. Axodendritic

The most numerous of all cells of CNS nervous tissue are the A. astrocytes. B. neurons. C. Schwann cells. D. microglia

A. astrocytes.

T/F The brain and spinal cord comprise the A. central nervous system. B. peripheral nervous system. C. peripheral ganglia. D. spinal nerves.

A. central nervous system.

What type of proteins are present in gap junctions that form water-filled channels between neurons? A. connexins B. myelin C. terminal boutons D. cell adhesion molecules (CAMs)

A. connexins

Botulism toxin prevents release of ACh, causing A. flaccid paralysis. B. hemiplegia. C. spastic paralysis. D. None apply.

A. flaccid paralysis.

The minimum depolarization needed to open Na+ gates is called the A. repolarization. B. threshold. C. refractory period. D. All-or-none law.

B. threshold.

Ion channels that open in response to depolarization are called A. ion-gated channels. B. voltage-gated channels. C. stimulation-gated channels. D. potential-gated channels.

B. voltage-gated channels.

The average resting membrane potential of an axon is A. -70mV. B. -85mV. C. 0 mV D. +30mV

A. -70mV.

An axon will depolarize only if the membrane potential reaches between -70mV and -55mV. This follows the A. All-or-none law. B. recruitment law. C. graduated law. D. threshold law

A. All-or-none law.

What is NOT true of the relative refractory period? A. Na+ channels are inactivated B. many Na+ channels are returning to a closed state C. K+ is moving out of the axon through its open channels D. a strong stimulus could cause a depolarization

A. Na+ channels are inactivated

The myelin sheaths of PNS neurons are produced by A. Schwann cells. B. oligodendrocytes. C. ependymal cells. D. leukocytes.

A. Schwann cells.

Chemical synapses A. have a delayed impulse transmission. B. utilize gap junctions. C. occur when two nerve cells are in direct contact with each other. D. do not require the release of neurotransmitters.

A. have a delayed impulse transmission.

Which type of cell of the CNS is phagocytotic? A. microglia B. satellite cells C. ependymal cells D. oligodendrocytes

A. microglia

Which of the following is NOT a structural classification of neurons? A. motor neuron B. bipolar neuron C. multipolar neuron D. pseudounipolar neuron

A. motor neuron

Regeneration of CNS axons may be prevented in part by inhibitory proteins in the membranes of the A. myelin sheath. B. neurons. C. astrocytes. D. satellite cells.

A. myelin sheath.

White matter is A. myelinated axons in the CNS. B. myelinated axons in the PNS. C. nonmyelinated cell bodies and dendrites in the CNS. D. nonmyelinated axons in the CNS.

A. myelinated axons in the CNS.

Which of the following is NOT true of dendrites? A. transmits action potentials toward the cell body B. are thin extensions of the cell body C. transmit graded electrochemical impulses toward the cell body D. contain receptive areas

A. transmits action potentials toward the cell body

Sensory neurons A. are multipolar and carry impulses toward the CNS. B. are pseudounipolar and carry impulses toward the CNS. C. are bipolar and carry impulses away from the CNS. D. are multipolar and carry impulses away from the CNS.

B. are pseudounipolar and carry impulses toward the CNS.

Neurotransmitter release would be inhibited by A. stimulating repolarization of the axon terminal. B. blocking Ca2+ influx in the axon terminal. C. blocking repolarization of the axon terminal. D. stimulating protein kinase activity.

B. blocking Ca2+ influx in the axon terminal.

Gliotransmitters A. include calcium ions. B. can stimulate neurons. C. form the blood-brain barrier. D. break down ATP

B. can stimulate neurons.

Repolarization is accomplished through a A. positive feedback loop. B. negative feedback loop. C. relative refractory loop. D. sodium equilibrium potential.

B. negative feedback loop.

The gap of exposed axon in the myelin sheath is the A. neurilemma. B. node of Ranvier. C. sheath of Schwann. D. white matter.

B. node of Ranvier.

The myelin sheaths of CNS neurons are produced by A. Schwann cells. B. oligodendrocytes. C. ependymal cells. D. leukocytes.

B. oligodendrocytes.

The mechanism that allows many Na+ ions to move into the axon is A. negative feedback. B. positive feedback. C. equilibrium feedback.

B. positive feedback.

Conduction of an action potential in a myelinated axon is called A. point to point conduction. B. saltatory conduction. C. refractory conduction. D. cable conduction.

B. saltatory conduction.

Blocking ____________ channels would prevent neuron depolarization. A. K+ B. Cl- C. Na+ D. Mg2+

C. Na+

During an action potential A. Na+ efflux causes depolarization. B. K+ influx causes repolarization. C. Na+ influx causes depolarization. D. K+ influx causes after-hyperpolarization.

C. Na+ influx causes depolarization.

What process is needed to return a membrane to its resting membrane potential with all ions in the correct locations? A. after-hyperpolarization B. all-or-none-law C. Na+/K+ pump D. refractory period

C. Na+/K+ pump

Action potentials would be conducted most rapidly by A. a 10 mm diameter myelinated axon. B. a 10 mm diameter unmyelinated axon. C. a 40 mm diameter myelinated axon. D. a 40 mm diameter unmyelinated axon.

C. a 40 mm diameter myelinated axon.

The blood-brain barrier results mostly from the action of __________, a type of glial cell. A. ependymal cells B. microglia C. astrocytes D. oligodendrocytes

C. astrocytes

Which cells are needed for the formation of synapses in the CNS? A. ependymal B. microglia C. astrocytes D. dendrites

C. astrocytes

Which division of the nervous system innervates involuntary effectors? A. central nervous system B. somatic nervous system C. autonomic nervous system D. associative nervous system

C. autonomic nervous system

Local anesthetics block conduction of action potentials in sensory neurons by A. inhibiting the release of acetylcholine. B. binding to potassium channels. C. binding to sodium channels. D. binding to calcium channels.

C. binding to sodium channels.

What coding system do neurons use to get a greater response? A. greater amplitude of stimuli B. greater Na+ concentration gradient C. increased frequency of stimuli D. more active Na+/K+ pump

C. increased frequency of stimuli

The disease ______________ is characterized by destruction of CNS myelin sheaths and the formation of hardened scars. A. Parkinson's B. Alzheimer's C. multiple sclerosis. D. myasthenia gravis

C. multiple sclerosis.

Which of the following is NOT a functional classification of neurons? A. motor or efferent B. interneuron or association C. multipolar D. sensory or afferent

C. multipolar

102. Which of the following is NOT true of EPSPs? A. they are graded responses B. they are capable of summation C. they have a refractory period D. they are initiated by neurotransmitters

C. they have a refractory period

A bundle of axons in the CNS is called a/an A. nerve. B. bundle. C. tract. D. neuron.

C. tract.

Neurotransmitters A. are released by endocytosis. B. all bind to the same receptor. C. usually regulate ion channels. D. are actively transported across the synaptic cleft.

C. usually regulate ion channels.

Retrograde transport A. moves toward the cell body. B. moves membranes, vesicles, and viruses. C. uses molecular motor proteins of dynein. D. All apply

D. All apply

The binding of a neurotransmitter to its receptor protein causes ion channels to open in the post-synaptic membrane. What type of gates are these? A. chemically-regulated gates B. voltage-regulated gates C. ligand-regulated gates D. Chemically-regulated gates and ligand-regulated gates are correct.

D. Chemically-regulated gates and ligand-regulated gates are correct.

Hyperpolarization in the postsynaptic cell is caused by A. excitatory postsynaptic potentials. B. inhibitory postsynaptic potentials. C. movement of K+ out of the cell. D. Inhibitory postsynaptic potentials and movement of K+ out of the cell are correct.

D. Inhibitory postsynaptic potentials and movement of K+ out of the cell are correct.

What type of neuron is found entirely in the CNS? A. sensory neuron B. interneuron C. association neuron D. Interneuron and association neuron are correct.

D. Interneuron and association neuron are correct.

The period of time when Na+ channels are recovering from their inactive state and K+ channels are still open is the A. repolarization. B. absolute refractory period. C. relative refractory period. D. Repolarization and relative refractory period are correct.

D. Repolarization and relative refractory period are correct.

Synaptic vesicles are docked to the plasma membrane of the axon terminal by a protein complex called A. boutons. B. connexins. C. synaptotagmins. D. SNARE.

D. SNARE.

Action potential transmission in the PNS is decreased if which cells are damaged? A. astrocytes B. microglia C. oligodendrocytes D. Schwann cells

D. Schwann cells

What type of proteins are present at chemical synapses to ensure the close proximity of the presynaptic and postsynaptic membranes? A. connexins B. myelin C. terminal boutons D. cell adhesion molecules (CAMs)

D. cell adhesion molecules (CAMs)

Which of the following effect(s) acetylcholine synaptic transmission? A. curare B. botulinum toxin C. strychnine D. curare and botulinum toxin.

D. curare and botulinum toxin.

Degeneration of spinal motor neurons in adults may be due to a lack of ____________ factor. A. brain-derived neurotrophic (BDNF) B. neurotrophin-3 C. nerve growth (NGF) D. glial-derived neurotrophic (GDNF)

D. glial-derived neurotrophic (GDNF)

Which of the following is NOT true of axonal transport? A. uses molecular motors B. can transport anterograde or retrograde C. has one fast and two slow components D. is a passive process

D. is a passive process

Axonal regeneration is inhibited by A. brain-derived neurotrophic factor. B. nerve growth factor. C. neurotrophin-3. D. myelin-associated inhibitory protein.

D. myelin-associated inhibitory protein

Which of the following is NOT a function of astrocytes? A. can take up NT from a synapse B. can stimulate or inhibit neurons C. needed to form synapses in the CNS D. phagocytose foreign material in the CNS E. form the blood-brain barrier

D. phagocytose foreign material in the CNS

Which of the following is NOT a function of neurotrophins? A. maintaining sympathetic ganglion B. sustaining neurons that use the NT dopamine C. embryonic development of neurons D. regeneration of injured motor neurons

D. regeneration of injured motor neurons