BIO 141: Chapter 12

True or False. Acetylcholine triggers the synthesis of the second messenger cAMP only in neurons of the PNS.

False

True or False. Any two EPSPs will override one IPSP.

False

True or False. In a myelinated fiber, only the initial segment in the trigger zone has voltage-regulated channels.

False

True or False. In the brain, neurons are more abundant than neuroglia.

False

True or False. Neurons move material away from the neurosoma by retrograde transport.

False

True or False. Oligodendrocytes serve the same purpose in the CNS that satellite cells do in the PNS.

False

True or False. The nervous system employs exclusively electrical means to send messages, whereas the endocrine system communicates by means of chemical messengers.

False

True or False. When a neuron is stimulated, Na+ gates open and allow Na+ to exit the cell.

False

True or False. Ependymal cells line the inner cavities of the CNS.

True

True or False. In most neurons, action potentials occur in the axon.

True

True or False. Memories are formed by neural pathways of modified synapses.

True

True or False. Most neurons have multiple dendrites.

True

True or False. Nitric oxide (NO) acts as a neuromodulator by altering synaptic function.

True

True or False. Norepinephrine is a monoamine.

True

True or False. Unipolar neurons have only a single process leading away from the neurosoma.

True

Which of the following is true regarding unmyelinated nerve fibers in the PNS? a) A Schwann cell folds its plasma membrane around several fibers. b) A Schwann cells wraps its plasma membrane around each individual fiber as it does with myelinated fibers. c) An oligodendrocyte cells wraps its plasma membrane around each fiber as it does with myelinated fibers. d) Satellite cells cluster around each axon to form a pseudo-myelin sheath. e) Astrocytes send extensions called perivascular feet to wrap each fiber.

a) A Schwann cell folds its plasma membrane around several fibers.

Conduction of a nerve impulse would be the fastest in which of the following? a) A large diameter myelinated fiber b) A small diameter myelinated fiber c) A large unmyelinated fiber d) A small unmyelinated fiber e) A small fiber with multiple Schwann cells

a) A large diameter myelinated fiber

A neuron receives a stimulus. Which of the following events happens next? a) A local potential develops b) Threshold is reached c) Hyperpolarization of the membrane d) Repolarization of the membrane e) A resting membrane potential is established

a) A local potential develops

How does a neuron transport enzymes produced in the neurosoma to its axon terminals? a) Along microtubules b) By diffusion c) Via cytoplasmic streaming d) Through co-transport e) Via exocytosis

a) Along microtubules

Which statement about the nervous and endocrine systems is true? a) Both systems are dedicated to maintaining stable internal conditions by detecting and responding to stimuli. b)The endocrine system helps maintains stable internal conditions, while the nervous system is dedicated to affecting change. c) The nervous system helps maintains stable internal conditions, while the endocrine system is dedicated to affecting change. d) The nervous system monitors internal conditions but cannot alter them. To affect change, it must activate the endocrine system. e) The endocrine system monitors internal conditions but cannot alter them. To affect change, it must activate the nervous system.

a) Both systems are dedicated to maintaining stable internal conditions by detecting and responding to stimuli.

The respiratory center gathers information from a variety of sources in order to set the rate and depth of breathing. This is an example of what type of neural circuit? a) Convergent b) Divergent c) Reverberating d) Parallel after-discharge

a) Convergent

What property of neurons allows them to respond to changes in the environment? a) Excitability b) Conductivity c) Secretion d) Permeability e) Convergence

a) Excitability

During the relative refractory period, the membrane is hyperpolarized and a larger incoming stimulus is required to trigger an action poential. How does this affect the response properties of a sensory neuron? a) Higher stimulus intensity will increase the rate at which the sensory neuron fires action potentials. b) Lower stimulus intensity will increase the rate at which the sensory neuron fires action potentials. c) Higher stimulus intensity will cause the sensory neuron to fire larger (higher amplitude) action potentials. d) Higher stimulus intensity will cause the sensory neuron to fire smaller (lower amplitude) action potentials. e) Lower stimulus intensity will cause the sensory neuron to fire narrower (shorter duration) action potentials.

a) Higher stimulus intensity will increase the rate at which the sensory neuron fires action potentials.

Where are unmyelinated nerve fibers surrounded by Schwann cells? a) In the PNS b) In the CNS c) In the PNS and CNS d) Nowhere. Unmyelinated nerve fibers are never surrounded by Schwann cells. e) In the CNS, but only during early development.

a) In the PNS

In PNS nerve fiber regeneration, how is a growing axon directed to its original destination? a) It grows within a regeneration tube b) The axonal terminals grow toward the neurosoma until the two severed fragments are reunited. c) The axon grows a collateral that is directed by growth factors secreted by the postsynaptic neuron. d) Injured Schwann cells produce a trail of prostaglandins to the original destination. e) Neurons cannot regenerate.

a) It grows within a regeneration tube

What is the most common type of neuron? a) Multipolar b) Bipolar c) Unipolar d) Anaxonic e) Dendritic

a) Multipolar

If a neuron is prevented from sending a neurotransmitter across a synapse to another cell, which neuron property is being inhibited? a) Secretion b) Excitability c) Conductivity d) Permeability e) Viability

a) Secretion

Which of these does not contribute to the cessation of the signal in a synaptic transmission? a) Synaptic vesicles secrete neurotransmitter by exocytosis. b) Neurotransmitter escapes from the synapse into the nearby extracellular fluid. c) Neurotransmitters are no longer released. d) The axon terminal reabsorbs some neurotransmitters by endocytosis. e) Enzymes in the postsynaptic cell break down some neurotransmitters.

a) Synaptic vesicles secrete neurotransmitter by exocytosis.

Where do most local potentials form in a neuron? a) The dendrites b) The neurosomas c) The axon hillock d) The trigger zone e) The Schwann cells

a) The dendrites

While both systems maintain homeostasis, how does the nervous system differ from the endocrine system? a) The nervous system releases neurotransmitters between cells, while the endocrine system releases hormones into the blood. b) The nervous system releases neurotransmitters into the blood, while the endocrine system releases hormones between cells. c) The nervous system releases hormones between cells, while the endocrine system releases neurotransmitters into the blood. d) The nervous system releases hormones into the blood, while the endocrine system releases neurotransmitters between cells. e) Both systems release hormones between cells, but only the nervous system releases neurotransmitters into the blood.

a) The nervous system releases neurotransmitters between cells, while the endocrine system releases hormones into the blood.

The opening of __________ gates produces an __________. a) chloride; IPSP b) sodium; IPSP c) calcium; IPSP d) potassium; EPSP e) calcium and sodium; IPSP

a) chloride; IPSP

A myelin sheath is composed primarily of __________. a) lipids b) carbohydrates c) glycoproteins d) proteins e) polysaccharides

a) lipids

Nerves are __________ of the nervous system. a) organs b) tissues c) organ systems d) organelles e) cells

a) organs

Accumulation of Ca2+ in the axon terminal is called __________, and probably plays an important role in __________. a) synaptic facilitation; short-term memory b) neural coding; immediate memory c) postsynaptic potential; long-term memory d) neural coding; short-term memory e) long-term potentiation; long-term memory

a) synaptic facilitation; short-term memory

What is the most common inhibitory neurotransmitter in the brain? a) γ-Aminobutyric acid (GABA) b) Noradrenaline c) Epinephrine d) Acetylcholine e) Norepinephrine

a) γ-Aminobutyric acid (GABA)

Which of these is an example of an EPSP in a typical neuron? a) A voltage change from 0 mV to +0.35 mV b) A voltage change from -70 mV to -69.5 mV c) A voltage change from -69.5 mV to -70 mV d) A voltage change from +35 mV to 0 mV e) A voltage change from -70 mV to -70.5 mV

b) A voltage change from -70 mV to -69.5 mV

Parkinson disease is a progressive loss of motor function due to the degeneration of specific neurons. These neurons secrete an inhibitory neurotransmitter that prevents excessive activity in motor centers of the brain. What neurotransmitter is this? a) Serotonin b) Dopamine c) Acetylcholine d) GABA e) Glutamate

b) Dopamine

In an action potential, which event directly follows repolarization? a) Threshold is reached b) Hyperpolarization of the membrane c) Depolarization of the membrane d)Hypopolarization of the membrane e) The resting membrane potential is reinstated

b) Hyperpolarization of the membrane

An inhibitory local potential causes which of the following? a) Depolarization of the plasma membrane b) Hyperpolarization of the plasma membrane c) Repolarization of the plasma membrane d) Neutralization of the plasma membrane e) Drifting of the membrane potential toward the resting membrane potential

b) Hyperpolarization of the plasma membrane

Some antidepressant drugs act by inhibiting monoamine oxidase (MAO). What is the function of this enzyme? a) It binds to chloride gates. b) It breaks down monoamines. c) It blocks sodium channels. d) It converts ATP to cyclic AMP. e) It degrades acetylcholine.

b) It breaks down monoamines.

If the potassium leak channels were suddenly blocked in a resting neuron, what would happen to its resting membrane potential? a) It would become more negative. b) It would become more positive. c) The RMP would be unaffected. d) It would hyperpolarize.

b) It would become more positive.

Which of the following is most likely to cause a rapid depolarization? a) Opening of chloride channels b) Opening of sodium channels c) Opening of potassium channels d) Inactivation of sodium channels e) Closing of sodium channels

b) Opening of sodium channels

Which glial cell is found wrapped around nerve fibers in the PNS? a) Oligodendrocytes b) Schwann cells c) Satellite cells d) Nodes of Ranvier e) Ependymal cells

b) Schwann cells

Most metabolic and regulatory functions in a neuron happen where? a) The axon b) The neurosoma c) The dendrites d) The axon hillock e) The Schwann cell

b) The neurosoma

A cholinergic synapse uses __________ as its neurotransmitter. a) monoamine b) acetylcholine c) epinephrine d) norepinephrine e) catecholamine

b) acetylcholine

Some __________ neurons are specialized to detect stimuli, whereas __________ neurons send signals to the effectors of the nervous system. a) efferent; afferent b) afferent; efferent c) motor; sensory d) efferent; inter- e) afferent; inter-

b) afferent; efferent

Local potentials are __________, meaning they vary in magnitude according to the strength of the stimulus. a) stabile b) graded c) self-propagating d) excitatory e) inhibitory

b) graded

When the voltage of a plasma membrane shifts from +35 mV toward 0 mV, the cell is __________. a) depolarizing b) repolarizing c) hyperpolarizing d) reaching the threshold e) exiting the threshold

b) repolarizing

What type of neural circuit is best for producing a prolonged output? a) A converging circuit b) A diverging circuit c) A reverberating circuit d) A presynaptic pool e) An autonomic pool

c) A reverberating circuit

In which part of a neuron is the postsynaptic membrane usually found? a) Axon terminal b) Axon c) Dendrite d) Perikaryon e) Axon collateral

c) Dendrite

Which of these happens first in an adrenergic synaptic transmission? a) ATP is converted to cyclic AMP. b) Adenylate cyclase is activated. c) G protein dissociates from the NE receptor. d) G protein binds to adenylate cyclase. e) Cyclic AMP induces several effects in the cell.

c) G protein dissociates from the NE receptor.

Inhibitory postsynaptic potentials (IPSPs) are associated with which of the following? a) Depolarization of the cell membrane b) Repolarization of the cell membrane c) Hyperpolarization of the cell membrane d) No change in the cell membrane potential e) No change of the threshold

c) Hyperpolarization of the cell membrane

What is another name for the autonomic nervous system? a) Visceral sensory division b) Somatic sensory division c) Visceral motor division d) Somatic motor division e) Central nervous system

c) Visceral motor division

In a neuron, the opening of sodium gates typically leads to __________. a) repolarization of the plasma membrane b) hyperpolarization of the plasma membrane c) depolarization of the plasma membrane d) drifting of plasma membrane voltage toward a more negative value e) plasma membrane voltage returning to the resting membrane potential

c) depolarization of the plasma membrane

Local potentials are __________, whereas action potentials are __________. a) irreversible; reversible b) self-propagating; local c) graded; all or none d) nondecremental; decremental e) produced by voltage-regulated channels; produced by gated channels

c) graded; all or none

A neuron can receive thousands of EPSPs from different neurons, and responds by triggering or not triggering an action potential. This addition and response to the net effect of postsynaptic potentials is called __________. a) temporal summation b) neural summation c) spatial summation d) neuronal coding e) recruitment

c) spatial summation

All of the following are typical characteristics of neurotransmitters except __________. a) they are synthesized by a presynaptic neuron b) they are released in response to stimulation c) they are released into the bloodstream before reaching the postsynaptic cell d) they bind to specific receptors on the postsynaptic cell e) they alter the physiology of the postsynaptic cell

c) they are released into the bloodstream before reaching the postsynaptic cell

The __________ division carries signals to the smooth muscle in the large intestine. a) visceral sensory b) somatic sensory c) visceral motor d) somatic motor e) afferent

c) visceral motor

Which neurotransmitter excites skeletal muscle and inhibits cardiac muscle? a) Norepinephrine b) Dopamine c) Histamine d) Acetylcholine e) β-Endorphin

d) Acetylcholine

Which of the following will cause the plasma membrane to hyperpolarize when at its RMP? a) An inflow of sodium b) An inflow of potassium c) An inflow of calcium d) An inflow of chloride e) An outflow of chloride

d) An inflow of chloride

Place the following events in synaptic transmission at a cholinergic synapse in order: A - A postsynaptic potential is produced; B - Voltage-gated calcium channels open and calcium enters the cell; C - ACh is released and diffuses across the axon terminal; D - A nerve signal arrives at an axon terminal; E - Ligand-gated sodium channels open and sodium enters the cell. a) B, D, C, A, E b) D, B, E, A, C c) B, C, D, E, A d) D, B, C, E, A

d) D, B, C, E, A

Place the following events of synaptic transmission at an adrenergic synapse in order: A - ATP is converted to cAMP B - The cell's metabolism is altered C - G protein binds adenylate cylase D - The G protein dissociates E - NE binds the receptor a) D, E, A, C, B b) D, E, C, A, B c) E, D, A, C, B d) E, D, C, A, B

d) E, D, C, A, B

Which of the following are effectors? a) Receptors b) Stimuli c) Reflexes d) Glands e) Sense organs

d) Glands

Which cells form myelin in the spinal cord? a) Schwann cells b) Astrocytes c) Satellite cells d) Oligodendrocytes e) Microglia

d) Oligodendrocytes

What causes hyperpolarization of a neuronal membrane? a) Sodium ions enter the cell. b) Sodium ions leave the cell. c) Potassium ions enter the cell. d) Potassium leave the cell. e) Both sodium and potassium ions leave the cell.

d) Potassium leave the cell.

In order to regenerate, a peripheral nerve fiber must have which of the following? a) All dendrites intact b) At least half the length of the fiber intact c) At least the entire axon and neurilemma intact d) The neurosoma and at least some neurilemma intact e) At least part of the neurosoma intact

d) The neurosoma and at least some neurilemma intact

Which of these happens first in a cholinergic synaptic transmission? a) Acetylcholine diffuses across the synaptic cleft. b) A postsynaptic potential is produced. c) Sodium enters the postsynaptic cell. d) The synaptic vesicles release acetylcholine. e) Acetylcholine binds to ligand-regulated gates.

d) The synaptic vesicles release acetylcholine.

The term "nerve fiber" refers to a(n) __________. a) nerve cell b) organelle in nerve cells c) organ d) axon e) bundle of macromolecules in nerve cells

d) axon

A traveling wave of excitation is known as a(n) __________. a) local potential b) graded potential c) action potential d) nerve signal e) depolarizing signal

d) nerve signal

What would be the best explanation for why myelinated fibers conduct signals faster than unmyelinated fibers? a) There are no sodium channels in unmyelinated fibers. b) Myelinated fibers contain more sodium ions. c) Myelinated fibers have more sodium-potassium pumps in their membranes. d) Active transport of sodium and potassium is faster in myelinated fibers. e) Electrical signals spread faster through insulated (myelinated) regions of axon.

e) Electrical signals spread faster through insulated (myelinated) regions of axon.

What is the opposite of presynaptic inhibition? a) Coding b) Integration c) Recruitment d) Summation e) Facilitation

e) Facilitation

During the absolute refractory period which of the following is true? a) If a neuron reaches threshold, the action potential goes to completion. b) The neuron fires at its maximum voltage if a stimulus depolarizes the neuron to threshold. c) The signal grows weaker with distance. d) It is possible to trigger a new action potential, but only with an unusually strong stimulus. e) No stimulus of any strength will trigger a new action potential.

e) No stimulus of any strength will trigger a new action potential.

Which of the following ions has the greatest influence on the resting membrane potential? a) Sodium b) Chloride c) Calcium d) Phosphate e) Potassium

e) Potassium

What is the primary site on a neuron for receiving signals from other neurons? a) The axon terminals b) The axons c) The axon collaterals d) The neurosomas e) The dendrites

e) The dendrites

Even though all action potentials are the same, the brain can differentiate a variety of stimuli by source and intensity. The mechanism by which the nervous system converts these action potentials into meaningful information is called neural __________. a) recruitment b) pooling c) integration d) facilitation e) coding

e) coding

About 90% of the neurons in the nervous system are __________ neurons. a) sensory b) motor c) afferent d) efferent e) inter-

e) inter-

The __________ division tends to prepare the body for action. a) sensory afferent b) motor afferent c) somatic motor d) parasympathetic e) sympathetic

e) sympathetic