Block 3_Chapter 12 Flashcards
Voltage-gated sodium channels have both an activation gate and a ________ gate.
inactivation
The site of intercellular communication between neurons is the
synapse
The effect that a neurotransmitter has on the postsynaptic membrane depends on
a. the frequency of neurotransmitter release.
b. the nature of the neurotransmitter.
c. the characteristics of the receptors.
d. the quantity of neurotransmitters released.
The ________ nervous system controls the skeletal muscles.
somatic
Type ________ fibers have the largest diameter axons.
A
Voltage-gated channels are present
in the membrane that covers axons
Functions of astrocytes include all of the following,
- responding to neural tissue damage
- guiding neuron development
- forming a 3D framework for the CNS
- maintaining the blood-brain barrier
Sensory neurons of the PNS are
unipolar
Which of the following are a type of glial cell found in the peripheral nervous system?
satellite cells
________ neurons form the afferent division of the PNS.
sensory
In the peripheral nervous system, Schwann cells participate in the repair of damaged nerves by
forming a cellular cord that directs axonal regrowth
The neurilemma of axons in the peripheral nervous system is formed by
Schwann Cells
The part of the peripheral nervous system that carries sensory information to the CNS is designated
afferent
Ion channels that are always open are called ________ channels.
leak
________ neurons are small and have no anatomical features that distinguish dendrites from axons.
axonic
The site in the neuron where the EPSPs and the IPSPs are integrated is the:
axon hillock
At the normal resting potential of a typical neuron, its Na-K ion exchange pump transports
3 intracellular sodium ions for 2 extracellular potassium ions.
Which type of synapse is most common in the nervous system?
chemical
Which point of the graph shows when potassium ion outflow exceeds sodium ion inflow?
hyperpolarization
The function of the astrocytes in the CNS includes which of the following?
- adjusting the composition of the interstitial fluid
- guiding neuron development
- maintaining the BBB
- repairing damaged neural tissue
If the chemically gated sodium channels in the postsynaptic membrane were completely blocked,
synaptic transmission would fail
The ion that triggers the release of acetylcholine into the synaptic cleft is
Calcium
________ open or close in response to binding specific molecules.
chemically gated channels
The efferent division of the peripheral nervous system innervates:
- skeletal muscle cells
- smooth muscle cells
- heart muscle cells
- glandular cells
________ line the brain ventricles and spinal canal.
ependymal cells
Which of the following types of nerve fiber possesses the fastest speed of impulse propagation?
Type A
Branches that may occur along an axon are called
collaterals
The axon is connected to the soma at the
axon hillock
Sensory information from skeletal muscle travels over _____ fibers.
Type A
Opening of sodium channels in the axon membrane causes
Depolarization and increased positive charge inside the membrane
EPSPs (excitatory postsynaptic potentials) occur when
Extra sodium ions enter a cell
Which of the following interactions between electrical and chemical gradients does not lead to the establishment of a neuron’s resting potential?
Electrical forces push sodium ions out of the cell
The same ________ can have different effects depending on the properties of the ________.
neurotransmitter; receptorr
In the process of continuous action potential propagation,
- the action potential is triggered by graded depolarization of the initial segment
- at threshold, sodium channels begin to open rapidly
- local currents depolarize the region just adjacent to the active zone
Which area of the graph occurs when there is a sudden in rush of sodium ions?
during depolarization, and the inactivation Na+ gates and the activation gates are both open
Neurotransmitter for release is stored in synaptic
vesicles
When a second EPSP arrives at a single synapse before the effects of the first have disappeared, what occurs?
temporal summation
IPSPs (inhibitory postsynaptic potentials)
are local hyperpolarizations
After acetylcholinesterase acts, the synaptic knob
reabsorbs the choline
Which of the following does influence the time necessary for a nerve impulse to be transmitted?
- presence or absence of a myelin sheath
- presence or absence of nodes
- length of axon
- diameter of the axon
Deteriorating changes in the distal segment of an axon as a result of a break between it and the soma is called ________ degeneration.
Wallerian
Adrenergic synapses release the neurotransmitter
NE
Axons terminate in a series of fine extensions known as
telodendria
When is the neuron in the refractory period?
Right after the absolute refractory period. About 2/3 of the way during repolarization
The all-or-none principle states that
all stimuli great enough to bring the membrane to threshold will produce identical action potentials
Which of the following are properties of cerebrospinal fluid?
- Surrounds the brain and spinal cord
- fills the brain ventricles
- transports nutrients
- circulates continuously
Ions can move across the plasma membrane in which of the following ways?
- through voltage-gated channels as in the action potential
- through passive or leak channels
- by ATP-dependant ion pumps like the sodium-potassium pump exchange pump
- through chemically-gated channels as in neuromuscular transmission
Which of the following is the most important excitatory amino acid neurotransmitter in the brain?
glutamate
