A Myelinated Nerve Fiber Is ______, Whereas An Unmyelinated Nerve Fiber Is ______.

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The two types of cells of the nervous system areneurons and neuroglia
Neuron cell processes responsible for transmitting impulses away from the cell body are calledaxons
The space between neurons is asynapse
The nervous systemdetects changes in the internal or external environment, controls the movement of muscles, regulates secretion, integrates information from several sources and uses it to respond appropriately.
__ convert information into nerve impulses that are transmitted to the CNS.sensory receptors
Sensory receptorsmonitor light, monitor sound, are part of the PNS, detect changes in and outside the body.
_________ support the axon from within.Neurofibrils
Every neuron hasa cell body
A neuron may haveone axon and many dendrites
What is unique to neurons?chromatophilic substance
Synaptic knobs are at the ends ofaxons
Myelincomprises much of the cell membrane of Schwann cells.
A myelinated nerve fiber is ______, whereas an unmyelinated nerve fiber is ______.white, and composing the white matter of the brain and spinal cord; gray, and composing the gray matter of the brain and spinal cord
Most of the neurons in the brain and spinal cord aremultipolar
What is a type of neuroglia?Astrocyte, oligondendrocyte, ependymal cell, schwann cell.
Which cells produce myelin in the brain and spinal cord?Oligodendrocytes
Which cell is only found in the PNS?Schwann cell
Dendrites on unipolar neurons are part ofsensory neurons
A reason that the CNS and PNS differ in their ability to regenerate after injury is thataxons of the CNS lack neurilemmae
Clusters of neuron cell bodies are calledganglia
Presynaptic neurons release neurotransmitters byexocytosis
Transmitting a nerve impulse from one neuron to another involves anerve impulse stimulating a presynaptic axon to release a neurotransmitter into a synaptic cleft.
A stimulus great enough to change the membrane potential and propagate an action potential is said to have reached _________.threshold
When a nerve fiber is polarized, the concentration ofNa+ is higher on the outside of the membrane and K+ is higher on the inside.
Saltatory conductionis faster than conduction on an unmyelinated fiber.
Which of the following ions cross cell membranes most readily?Potassium
If a resting potential becomes more negative, the membrane ishyperpolarizing
What is the correct sequence of events that follows a threshold potential?
1. The membrane depolarizes.
2. Sodium channels open and sodium ions diffuse inward.
3. The membrane repolarizes.
4. Potassium channels open and potassium ions diffuse outward.
2,1,4,3
Each neuron in the CNS receives input fromthousands of axons
The neurotransmitter that controls skeletal muscle contraction isacetylcholine
Drugs that increase the actions of norepinephrine and/or serotonin by keeping them in synapses longer are most likely used to treatclinical depression
During an action potential, calcium ions causesodium channels to close
The types of neurons that are organized into neuronal pools areinterneurons
Convergence refers toaxons from neurons in different parts of the nervous system contacting the same neuron.
Diverging axons amplify an impulse bycontacting many neurons.
An immune response that triggers inflammation of the spinal cord and brain, leaving scars ismultiple sclerosis
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 becausethe number of receptors to which the drug binds on neurons has declined.
The neurotransmitter most likely produced when a person uses a drug that creates a sense of well-being isdopamine
A nerve is a single neuron that transmits nerve impulses.False
Neuroglia are specialized to react to environmental change, and neurons support neuroglia.False
The brain and spinal cord comprise the central nervous system.True
Sensory receptors are part of the CNS.False
Axon branches are called collaterals.True
Nodes of Ranvier lie between neurons.False
The space between neurons is called the neuronal space.False
During the absolute refractory period, a stimulus of high intensity may trigger a nerve impulse.False
In convergence, two or more incoming fibers contact a single neuron, whereas in divergence, impulses leaving a neuron pass into several output fibers.True
Muscles and glands that respond to nerve impulses are called _______.effectors
A(n) ______ is the junction between neurons.synapse
The difference in electrical charge between the inside and outside of a polarized neuron cell membrane is called the ______ ______.resting potential
A series of similar stimuli that increases change in local membrane potential is called _______.summation
The somatic nervous system controls voluntary activities.True
has two processes (one axon, one dendrite)Bipolar neuron
lie within the brain or spinal cord and form links between other neuronsInterneuron
carry impulses out of the CNS to effector cellsmotor neuron
has many processes arising from their cell body (one axon, many dendrites)multipolar neuron
carry impulses from peripheral body parts to the CNSsensory neuron
Has a single process extending from its cell bodyunipolar neuron
structural support, formation of scar tissue, transport substances between neurons and blood vesselsastrocytes
form layer through which substances diffuse between interstitial fluid of brain and spinal cord and cererbrospinal fluidependymal cells
phagocytosismicroglial cells
form myelin sheath in brain and spinal cordOligodendrocytes
support ganglia in the PNSsatellite cells
speed neurotransmissionSchwann cells
creates sense of well beingnorepinephrine
memory/vasodilationnitric oxide
promotes alertnesshistamine
pain perception(excitatory)substance P
sleepinessserotonin
pain reductionEnkephalins