Ch.11 Homework
what is the resting membrane potential of a typical neuron?
-70 mV
how many synaptic connections from different presynaptic neurons does an average neuron have?
10,000
what is the period during an action potential when a nerve fiber cannot be stimulated to produce an additional action potential no matter how strong the stimulus?
absolute refractory period
what type of neuron carries information toward the central nervous system (CNS)?
afferent
which of the following events does not occur when the action potential is propagated along the axon?
as potassium ion channels activate, an action potential is triggered and spreads positive charges down the axon.
which of the following neuroglia would be more likely to form a brain tumor because of their ability to rapidly divide following brain injury?
astrocyte
which neuroglial cells help form the blood-brain barrier?
astrocytes
regulation of heart rate, blood pressure, and digestive functions are carried out by the _______
autonomic nervous system
where are voltage-gated channels most abundant?
axolemma
which of the following terms does not refer to a structural type of synapse?
axolemma
the conducting region of the neuron is the _______
axon
what neuron structure does not contain protein-making organelles?
axon
what specific part of the neuron communicates with a target cell and serves as the secretory region of the cell?
axon terminals (synaptic knobs)
which of the following structures can generate an action potential?
axons
most sensory neurons such as the ones found in the special sense organs are structurally classified as ____ neurons.
bipolar
which of the following are organs of the central nervous system?
brain and spinal cord
what ions triggers synaptic vesicles to release neurotransmitters into the synaptic cleft?
calcium
what must be intact for a neuron to regenerate in the peripheral nervous system (PNS)?
cell body
bundles of axons known as tracts are part of the __________
central nervous system (CNS)
the majority of synapses in the nervous system are ______
chemical
influx of which of the following ions can cause an inhibitory postsynaptic potential (IPSP) to be produced?
chloride ions
what kind of conduction occurs when each section of the axolemma has to be depolarized to threshold in sequence along the entire axolemma for a current to spread down the length of the axon?
continuous
which sequence of structures correctly indicates the direction in which an electrical signal is carried in a typical multipolar neuron?
dendrites, cell body, and axon
the influx of positive charges makes the membrane potential more positive and is known as _____
depolarization
what term refers to a temporary change in the cell's membrane potential that makes it less negative (or more positive)?
depolarization
which of the following characteristics is not associated with schwann cells?
envelop parts of several axons with multiple processes
what is the ciliated neuroglial cell the functions to circulate cerebrospinal fluid?
ependymal cells
which of the following events is most likely to trigger an action potential?
excitatory postsynaptic potential (EPSP)
what are clusters of cell bodies within the peripheral nervous system (PNS) called?
ganglia
which of the following features is not a structural component of chemical synapses?
gap junction
which of the following characteristics makes myelin such an excellent insulator for axons?
high lipid content
a series of measurements with a voltmeter show a neuron's membrane potential becoming more negative, from -70 mV to -85 mV. this neuron is experiencing a _______.
hyperpolarization phase
the majority of neurons are functionally classified as ______ neurons.
interneurons
which of the following terms is not associated with a general type of function found in the nervous system?
internode
what type of ion channel is always open?
leak
which type of channel opens in response to a chemical binding to a receptor on the channel?
ligand-gated
which of the following mechanisms does not terminate the effects of a neurotransmitter?
movement back to the cell body by retrograde axonal transport
the most common type of neuron in the human body is _______
multipolar
what forms the white matter of the spinal cord?
myelinated axons
what is the process of putting together all the excitatory and inhibitory stimuli that determine whether a neuron will or will not fire an action potential?
neural integration
what structure contains the bulk of the schwann cell's cytoplasm and organelles?
neurolemma
what cell type forms the myelin sheath in the central nervous system (CNS)?
oligodendrocytes
during saltatory conduction, action potentials are generated _________
only at nodes of Ranvier of myelinated axons
which of the following terms refers to the neuron that delivers a message to a target cell?
presynaptic
what neuroglial cells surround and support the cell bodies of neurons and have intertwined processes that link them with other parts of the neuron?
satellite cells
what structure found in the peripheral nervous system (PNS) promotes regeneration of a damaged axon?
schwann cell
the autonomic nervous system does not carry signals to ________
skeletal muscle
which of the following effectors is controlled by the somatic motor division?
skeletal muscle
what is the most metabolically active part of the neuron?
soma
which division of the peripheral nervous system (PNS) carries signals from the bones, joints, skin, and organs of vision to the central nervous system (CNS)?
somatic sensory
which of the following characteristics is the fundamental process for most functions of the nervous system?
synaptic transmission
which of the following events occurs when EPSPs arrive rapidly at a single synapse?
temporal summation
resting membrane potential is maintained by the Na+/K+ ATPhase, which brings _________
two potassium ions into the cytosol and three sodium ions into the extracellular fluid
which type of fiber has the largest diameter?
type A
which type of fiber has the slowest conduction speed?
type C
which of the following factors is not associated with local potentials?
useful for long distances
what channels open in response to changes in membrane potential?
voltage-gated