Nervous System I: Basic Structure and Function
Multiple Choice Questions
- The cytoplasmic extensions that, together with the cell body, provide the main receptive surfaces for neurons are
- chromatophilic substance (Nissl bodies).
- The two types of cells of the nervous system are
- axons and dendrites.
- neurons and neuroglia.
- motor neurons and sensory neurons.
- Schwann cells and microglia.
- The functional connection between two neurons is a
- gap junction.
- The nervous system
- detects changes in the internal or external environment.
- controls the movement of muscles.
- integrates information from several sources and uses it to determine an appropriate response.
- all of the above
- Neurons that conduct impulses from the CNS to muscles or glands are
- sensory neurons.
- motor neurons.
- unipolar neurons.
- Sensory receptors
- monitor light
- monitor sound.
- detect changes in and outside the body.
- all of the above.
- Three general functions of the nervous system are
- sensory, motor, and predictive.
- integrative, motor, and sensory.
- predictive, manipulative, and integrative.
- reflexive, sensory, and predictive.
- Masses of myelinated nerve fibers appear
- A neuron may have
- one axon and many dendrites.
- one dendrite and many axons.
- no dendrites.
- no axons.
- _________ support the axon from within.
- Nodes of Ranvier.
- Every neuron has
- many axons.
- a cell body.
- a neurilemma.
- Which of the following is unique to neurons?
- Golgi apparatus
- Chromatophilic substance
- is released from a neuron and travels to another neuron.
- consists of layers of lipids and proteins that wrap around an axon.
- is produced in response to bacterial infection.
- is a form of chromatophilic substance that fills Schwann cells.
- A myelinated nerve fiber is ______, whereas an unmyelinated nerve fiber is ______.
- gray, and composing the gray matter of the brain and spinal cord; white, and composing the white matter of the brain and spinal cord
- white, and composing the gray matter of the brain and spinal cord; gray, and composing the white matter of the brain and spinal cord
- white, and composing the white matter of the brain and spinal cord; gray, and composing the gray matter of the brain and spinal cord
- white, and composing the gray matter of the brain and spinal cord; red, and composing the white matter of the brain and spinal cord
- Myelin is rich in ___________.
- nucleic acids
- Which of the following is(are) a type of neuroglia?
- Schwann cell
- All of the above
- Which cells produce myelin in the brain and spinal cord?
- Schwann cells
- A reason that the axons in the CNS and PNS differ in their ability to regenerate after injury is that
- axons of the CNS lack myelin.
- axons of the CNS lack neurilemmae.
- peripheral nerves lack Schwann cells.
- peripheral nerves lack endoneurium.
- Most of the neurons in the brain and spinal cord are
- In order for a severed peripheral nerve to regenerate and recover its original function, nerve fibers must sprout and enter tubes formed by
- basement membranes and connective tissues.
- former axons.
- nodes of Ranvier.
- Which of the following cells is found only in the PNS?
- Microglial cell
- Schwann cell
- Dendrites on unipolar neurons are parts of
- sensory neurons.
- motor neurons.
- efferent neurons.
- Clusters of neuron cell bodies in the PNS are called _____.
- Which of the following neuroglia are not part of the CNS?
- Ependymal cells
- Satellite cells
- Synaptic knobs are at the ends of
- cell bodies.
- Presynaptic neurons release neurotransmitters by ______________.
- active transport.
- When an action potential passes over the surface of a synaptic knob, the contents of the vesicles are released in response to the presence of
- calcium ions.
- sodium ions.
- If a neuron receives a series of stimuli whose effect is excitatory but subthreshold, the neuron is more excitable to incoming stimulation than before and is said to be
- Transmitting an impulse from one neuron to another involves a(n)
- impulse stimulating presynaptic dendrites to release a neurotransmitter into a synaptic cleft.
- impulse stimulating a presynaptic axon to release a neurotransmitter into a synaptic cleft.
- neurotransmitter traveling from presynaptic dendrites across a synapse to postsynaptic axons or a cell body.
- neurotransmitter traveling from postsynaptic axons across a synapse to presynaptic dendrites or a cell body.
- Action potentials are related to impulses conducted along an axon in that
- many impulses are required to cause one action potential.
- active transport of Na+ and K+ are required for impulse conduction but not for an action potential.
- impulses are stronger responses than are action potentials.
- propagation of a series of action potentials along a nerve cell fiber constitutes an impulse.
- A stimulus great enough to change the membrane potential and propagate an action potential is said to have reached _________.
- When a nerve fiber is polarized, the concentration(s) of
- Na+ and K+ are higher on the inside of the membrane.
- Na+ and K+ are higher on the outside of the membrane.
- Na+ is higher on the inside of the membrane and K+ is higher on the outside.
- Na+ is higher on the outside of the membrane and K+ is higher on the inside.
- Saltatory conduction
- occurs only if the myelin sheath is continuous.
- occurs only if nodes of Ranvier are lacking.
- is faster than conduction on an unmyelinated fiber.
- is slower than conduction on an unmyelinated fiber.
- The most rapid conduction of an impulse along an axon occurs on a fiber that is
- thick and myelinated.
- thick and unmyelinated.
- thin and myelinated.
- thin and unmyelinated.
- Which of the following ions cross neuron cell membranes most readily?
- If a resting potential becomes more negative, the membrane is
- What is the correct sequence of events along an axon that follows a membrane reaching threshold potential?
- The membrane depolarizes.
- Sodium channels open and sodium ions diffuse inward.
- The membrane repolarizes.
- Potassium channels open and potassium ions diffuse outward.
- 3, 2, 4, 1
- 2, 1, 4, 3
- 1, 2, 4, 3
- 4, 1, 3, 2
- A nerve cell membrane becomes depolarized as a result of
- calcium leaving the nerve cell.
- some ion channels being opened while others are closed.
- the relative ease with which K+ diffuses into the nerve cell.
- Na+ being prevented from passing through the membrane.
- Which of the following molecules is responsible for "runner's high," a good feeling that accompanies long-distance running?
- Beta endorphin
- An excitatory postsynaptic potential lasts for about
- 15 minutes.
- 15 seconds.
- 15 milliseconds.
- 15 microseconds.
- Each neuron in the CNS may receive input from
- only one synaptic knob.
- one synaptic knob at each end.
- about 10 dendrites.
- thousands of axons.
- An action potential is triggered if
- EPSPs overpower IPSPs.
- IPSPs overpower EPSPs.
- chloride channels open.
- the membrane hyperpolarizes.
- The neurotransmitter that controls skeletal muscle contraction is
- beta endorphin.
- nitric oxide.
- Viagra is a drug used to treat erectile dysfunction by dilating arteries in the penis. The neurotransmitter that Viagra affects is
- nitric oxide.
- Neurotransmitters that are modified amino acids are
- dopamine, serotonin, epinephrine, and norepinephrine.
- enkephalins, endorphins, and substance P.
- aspartic acid, glutamic acid, glycine, and GABA.
- potassium, sodium, and calcium ions
- Drugs that increase the actions of norepinephrine and/or serotonin by keeping them in synapses longer are most likely used to treat
- multiple sclerosis.
- Tay-Sachs disease.
- clinical depression.
- erectile dysfunction.
- In reuptake
- an action potential reverses direction.
- a neuropeptide breaks down into amino acids, which act as neurotransmitters.
- a neurotransmitter that has already been released into the synaptic cleft is taken back into the synaptic knob of the presynaptic neuron or into nearby neuroglia or neurons.
- an enzyme breaks down a neurotransmitter and then another enzyme builds it back up.
- Drugs that inhibit the enzyme monoamine oxidase
- allow increased activity of norepinephrine.
- decompose norepinephrine.
- decrease the activity of serotonin.
- decompose serotonin.
- The types of neurons that are organized into neuronal pools are
- Schwann cells.
- Convergence refers to
- dendrites from neurons in different parts of the nervous system contacting the same neuron.
- axons from neurons in different parts of the nervous system contacting the same neuron.
- dendrites from the same neuron touching each other.
- a neuroglial cell that contacts many neurons.
- Diverging axons amplify an impulse by
- contacting many neurons.
- returning the impulse to the neuron of origin.
- splitting into multiple axons.
- stimulating themselves.
- Neural stem cells can be harvested from autopsies and stored, alive, in banks, whereas neurons cannot, because
- people do not will them to science.
- neural stem cells have lower oxygen and energy requirements than neurons.
- neural stem cells have higher oxygen and energy requirements than neurons.
- neural stem cells have more globular shapes than neurons.
- Migraine results from
- release of calcitonin gene-related peptide from the trigeminal nerves at the base of the brain, in response to a spreading wave of excitation followed by lack of response from the cortex.
- not eating enough chocolate, which causes a spreading effect in the cortex.
- a neurotransmitter deficiency.
- release of an abnormal form of beta endorphin from the trigeminal nerves at the base of the brain, in response to cortical stimulation.
- An immune response that affects the myelin coating on axons throughout the spinal cord and brain, triggering inflammation and leaving scars, is
- muscular dystrophy.
- multiple sclerosis.
- Alzheimer disease.
- amyotrophic lateral sclerosis.
- Drugs that decrease membrane permeability to sodium
- are used as local anesthetics.
- prevent nerve impulses from passing through the affected body part.
- lessen pain.
- all of the above.
- Opiate drugs derived from poppies relieve pain in humans because the human nervous system has
- receptors for endogenous opiates.
- sodium and potassium membrane channels.
- Marjorie takes an anti-anxiety drug so that she can sleep better and remain calm enough to study effectively. She begins by taking 25 milligrams every evening, but within a month this dose is no longer helping, so she takes two pills. After another month this dosage is no longer effective. This is happening because
- her immune system is rejecting the drug.
- she has developed tolerance, which means that her liver can no longer metabolize the drug, so it remains active for too long.
- the number of receptors to which the drug binds on neurons has declined.
- the number of receptors to which the drug binds on neurons has increased.
- The neurotransmitter most likely produced when a person uses a drug that creates a sense of well-being is
- glutamic acid.
- substance Q.
- A drug that functions as an agonist
- activates a receptor, helping a neurotransmitter bind or triggering an action potential in some other way.
- causes great pain if taken in too high a dose.
- blocks a receptor so that the neurotransmitter cannot bind.
- relieves pain.
True / False Questions
- A nerve is a single neuron that transmits impulses.
- Neuroglia are specialized to react to environmental change, and neurons support neuroglia.
- The brain and spinal cord comprise the central nervous system.
- Sensory receptors are part of the CNS.
- The somatic nervous system controls voluntary actions and the autonomic nervous system oversees involuntary actions.
- Axon branches are called collaterals.
- Myelin is composed largely of carbohydrates.
- Nodes of Ranvier lie between neurons.
- Astrocytes structurally support neurons and also provide important signals and nutrients to neurons.
- Interneurons are specialized to carry impulses from receptor cells into the brain or spinal cord.
- A mixed nerve includes different neuroglial cells.
- The space between neurons is called the neuronal space.
- During the absolute refractory period, a stimulus of high intensity may trigger a nerve impulse.
- Because the response of a nerve fiber is all-or-none, a greater intensity of stimulus does not produce a stronger impulse.
- Enkephalins are neuropeptides.
- In convergence, two or more incoming fibers contact a single neuron, whereas in divergence, impulses leaving a neuron pass into several output fibers.
- Several nerve fibers converging onto one neuron amplifies impulses.
Fill in the Blank Questions
- The cells in the nervous system that fill spaces and support neurons both physically and nutritionally are called ______.
- Muscles and glands that respond to nervous stimulation are called _______.
- Sheaths of ______ cells often enclose the larger axons outside of the brain and spinal cord.
- A(n) ______ is the junction between neurons.
- The difference in electrical charge between the inside and outside of a polarized neuron cell membrane is called the ______ ______.
- An impulse conducted along an axon consists of a wave of ______ ______ moving away from a point of stimulation.
- A series of similar stimuli that induces change in local membrane potential is called _______.
- Neuropeptides that affect a neuron's response to other neurotransmitters are called _______.
- If a neurotransmitter hyperpolarizes a cell membrane and an action potential is less likely, the change is called ______ ______ ______.
inhibitory postsynaptic potential
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