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Which of the following is NOT one of the basic functions of the nervous system? |
regulation of neurogenesis |
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Which of the following allows us to consciously control our skeletal muscles? |
The somatic nervous system |
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What part of the nervous system performs information processing and integration? |
Central nervous system |
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Which of the following peripheral nervous system (PNS) neuroglia form the myelin sheaths around larger nerve fibers in the PNS? |
Schwann cells |
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Which of the following is the conducting region of the neuron? |
axon |
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Which of the following are gaps found along a myelin sheath? |
Nodes of ranvier |
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Which of the following is NOT a difference between graded potentials and action potentials? |
Spatial summation is used to increase the amplitude of a graded potential; temporal summation is used to increase the amplitude of an action potential |
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Which neuroglia are the most abundant and versatile of the glial cells? |
astrocytes |
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Which of the following types of neurons carry impulses away from the central nervous system (CNS)? |
motor |
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Where do most action potentials originate? |
Initial segment |
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What opens first in response to a threshold stimulus? |
Voltage-gated Na+ channels |
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What characterizes depolarization, the first phase of the action potential? |
The membrane potential changes from a negative value to a positive value. |
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What is the first change to occur in response to a threshold stimulus? |
Voltage-gated Na+ channels change shape, and their activation gates open. |
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What type of conduction takes place in unmyelinated axons? |
continuous conduction |
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An action potential is self-regenerating because __________. |
depolarizing currents established by the influx of Na+ flow down the axon and trigger an action potential at the next segment |
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Why does regeneration of the action potential occur in one direction, rather than in two directions? |
The inactivation gates of voltage-gated Na+ channels close in the node, or segment, that has just fired an action potential. |
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What is the function of the myelin sheath? |
The myelin sheath increases the speed of action potential conduction from the initial segment to the axon terminals. |
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What changes occur to voltage-gated Na+ and K+ channels at the peak of depolarization? |
Inactivation gates of voltage-gated Na+ channels close, while activation gates of voltage-gated K+ channels open. |
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In which type of axon will velocity of action potential conduction be the fastest? |
Myelinated axons with the largest diameter |
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Ions are unequally distributed across the plasma membrane of all cells. This ion distribution creates an electrical potential difference across the membrane. What is the name given to this potential difference? |
Resting membrane potential (RMP) |
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Sodium and potassium ions can diffuse across the plasma membranes of all cells because of the presence of what type of channel? |
Leak Channels |
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On average, the resting membrane potential is -70 mV. What does the sign and magnitude of this value tell you? |
The inside surface of the plasma membrane is much more negatively charged than the outside surface. |
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The plasma membrane is much more permeable to K+ than to Na+. Why? |
There are many more K+ leak channels than Na+ leak channels in the plasma membrane |
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Which of the following is NOT a type of circuit? |
Pre-discharge circuits |
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What type of stimulus is required for an action potential to be generated? |
A threshold lever depolarization |
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The __________ is due to the difference in K+ and Na+ concentrations on either side of the plasma membrane, and the difference in permeability of the membrane to these ions. |
Resisting membrane potential |
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The small space between the sending neuron and the receiving neuron is the |
Synaptic cleft |
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A molecule that carries information across a synaptic cleft is a |
neurotransmitter |
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When calcium ions enter the synaptic terminal, |
they cause vesicles containing neurotransmitter molecules to fuse to the plasma membrane of the sending neuron. |
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When neurotransmitter molecules bind to receptors in the plasma membrane of the receiving neuron, |
ion channels in the plasma membrane of the receiving neuron open. |
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If a signal from a sending neuron makes the receiving neuron more negative inside, |
the receiving neuron is less likely to generate an action potential |
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Unmyelinated fibers conduct impulses faster than myelinated fibers. T or F? |
F |
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The sodium-potassium pump ejects two Na+ from the cell and then transports three K+ back into the cell in order to maintain the concentration gradients for sodium and potassium. T or F? |
F |
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What component of the reflex arc determines the response to a stimulus? |
Integration center |
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reflexes |
rapid automatic responses to a stimulus in which the particular stimulus always produces the same motor response |
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autonomic nervous system |
conducts impulses from CNS to internal organ muscles |
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A potential of -90 mV is considered __________. |
hyperpolarized |
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numerous nerve impulses arriving at a synapse at closely timed intervals exert a cumulative effect. |
temporal summation |
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central nervous system. |
Consist of brain and spinal cord |
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What is the difference between nerves and tracts? |
Bundles of neuron processes are called tracts in the CNS and nerves in the PNS. |
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Peripheral nervous system (PNS) |
consists mainly of nerves that extend from the brain and spinal cord |
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Which of the following best describes the concept of integration? |
The nervous system processes and interprets sensory input and decides what should be done at each moment. |
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somatic nervous system |
conducts impulses from CNS to skeletal muscles |
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Which of the following factors is associated with increased conduction velocity in an axon? |
large diameter |
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Which criterion is used to structurally classify neurons? |
the number of processes extending from their cell body |
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any stimulus above this intensity will result in an action potential in a neuron? |
Threshold stimulus |
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During which phase of an action potential are voltage-gated K+ channels open, while voltage-gated Na+ channels are closed? |
repolarizing phase |
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Neurons can be classified structurally by the number of processes extending from their cell bodies. Which of the following is the most common neuron type in humans? |
multipolar |
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Which of the following neurotransmitters acts as a natural opiate? |
endorphines |
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Which of the following is NOT true of efferent neurons? |
Efferent neurons are bipolar |
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Which of the following is NOT a biogenic amine neurotransmitter? |
acetylcholine |
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neurotransmitter? |
binds to the postsynaptic receptor/channel |
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Which of the following circuit types is exemplified by impulses that travel from a single neuron of the brain, activate one hundred or more motor neurons in the spinal cord, and excite thousands of skeletal muscle fibers? |
diverging circuits |
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norepinephrine? |
neurotransmitter of postganglionic neurons in the sympathetic nervous system |
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Which of the following membrane ion channels open and close in response to changes in the membrane potential? |
voltage- gated channels |
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Which of the following neuroglia is most responsible for helping determine capillary permeability in nervous tissue? |
astrocytes |
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Which of the following is NOT true of chemical synapses? |
They transmit nerve impulses directly from one neuron to another. |
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Which of the following statements concerning inhibitory synapses (IPSPs) is correct? |
The postsynaptic membrane becomes more permeable to potassium and chloride. |
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The somatic sensory (afferent) fibers of the peripheral nervous system transmits information from the __________ to the CNS. |
Skin |
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Which of the following is a rare type of sensory neuron that is found in special sensory structures like the retina of the eye? |
bipolar |
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Which disease is directly related to demyelination? |
multiple sclerosis |
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acetylcholine? |
excites skeletal muscle |
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A neuron will not respond to a second stimulus of equal strength to the first stimulus to which it has already responded because __________. |
the neuron is in the absolute refractory period |
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Which type of ion channel opens when a chemical binds to it? |
ligand- gated channel |
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Which of the following substances plays the major role in generating the membrane potential of a neuron through its passive movement? |
potassium |
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Which of the following conditions would cause synaptic potentiation? |
… |
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What is the primary difference between the somatic nervous system and the autonomic nervous system? |
The somatic nervous system allows us to consciously control our skeletal muscles, and the autonomic nervous system controls activity that humans cannot consciously control, such as the pumping of the heart and the movement of food through the digestive tract. |
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Caffeine’s stimulatory effects result from blocking receptors for which neurotransmitter? |
adenosine |
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Organelles for degradation or recycling are moved through the axon by _____. |
retrograde movement |
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Which of the following types of glial cells line the central cavities of the brain and spinal cord, where they help to circulate the cerebrospinal fluid? |
ependymal cells |
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The sodium-potassium ion pump will __________. |
pump three sodium ions out of the cell for every two ions of potassium it brings into the cell |
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From where can collaterals emerge on a myelinated nerve? |
from the nodes of Ranvier |
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Which of the following membrane ion channels in the neuron are always open? |
leakage channels |
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Which part of the action potential occurs when the Na+ channels are inactivating and K+ channels open? |
repolarization |
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Which of the following characteristics is NOT associated with a myelinated nerve fiber? |
slow conduction of nerve impulses |
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Which of the following is NOT a function of the myelin sheath? |
to recapture and recycle released neurotransmitters |
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Which of the following electrical events occurs when a certain threshold is reached? |
Action potential |
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Which of the following events is NOT involved in the transfer of information across a chemical synapse? |
Ions flow directly from one neuron to the next. |
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The interior of a nerve cell has a slight excess of negative charge because __________. |
potassium diffuses out of the cells |
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Which of the following substances is NOT a neurotransmitter? |
acetylcholinesterase |
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Which of the following types of glial cells are the most abundant and versatile and aid in making exchanges between capillaries and neurons? |
astrocytes |
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Which of the following line the central cavities of the brain and spinal cord and provide a fairly permeable barrier between the CSF and nervous tissue? |
ependymal cells |
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What is the difference between the clusters of cell bodies called nuclei and those known as ganglia? |
Nuclei exist in the CNS, ganglia in the PNS. |
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the all-or-none phenomenon? |
an action potential occurring only if enough Na+ enters the cell and threshold is achieved |
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G-protein-linked receptors? |
indirect synaptic responses that are complex, prolonged, and often diffuse as a result of the production of intracellular second-messenger molecules |
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saltatory conduction? |
conduction process in myelinated axons where the electrical signal appears to jump from gap to gap along the axon |
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The Nissl bodies seen in the neuron cell body represents which cellular organelle? |
Rough E.R. |
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