Test 4- Ch. 12 SB Review
Initially, the voltage-gated Na+ channels are closed and the membrane potential is ______ mV. As Na+ flows in the membrane potential changes to ______ mV and the threshold is reached.
-70; -55
The nerve impulse has the voltage-gated ______ channels opened first followed by the opening of the voltage-gated ______ channels.
Na+; K+
Which describes the propagation of depolarization down an axon?
The flow of Na+ to downstream regions causes depolarization of adjacent regions.
Action potentials are always propagated along an axon at the same ______ but ______ can vary depending on the strength of the stimulus.
amplitude;frequency
A substance synthesized at the cell body must undergo ______ transport to reach the synaptic knobs.
anterograde
The voltage-gated sodium channels ______ during repolarization.
are inactivated
______ are star shaped.
astrocytes
Cytoplasm within an axon is called ______.
axoplasm
Many excitatory neurotransmitters cause the opening of channels that allow for the flow of ______.
both Na+ and K+
The ependymal cells help produce ______.
cerebrospinal fluid
The main activity of the ______ is the propagation of an action potential along the axolemma.
conductive segment
Glial cells ______ transmit electrical impulses.
do not
The lining ventricles of the brain is a location of ______.
ependymal cells
During an action potential, voltage-gated potassium channels open after voltage-gated sodium channels. The effect this has on the membrane potential is ______.
it becomes less positive and more negative
The myelin sheath is made of a high percentage of ______.
lipids
Cells that wander through the CNS and replicate in response to infection are called
microglia
Which glial cells remove debris from damaged or dead nervous tissue?
microglia
Most motor neurons are ______.
multipolar
______ neurons are most common.
multipolar
A cablelike bundle of axons in the peripheral nervous system is called a ______.
nerve
A ______ is the propagation of an action potential along an axon.
nerve impulse
The components of nervous tissue that conduct electrical impulses are ______.
neurons
______ are released from neurons in response to conductive activity.
neurotransmitters
Propagation of depolarization only flows away from the cell body towards the synaptic knob because ______.
previous regions of the axon are already repolarized
Membrane molecules that use the energy of ATP to move ions against a concentration gradient are called
pumps
The function of a neuron is dependent on ______.
resting membrane potentials changing
The flow of ______ ion is the most common cause of depolarization.
sodium
A damaged axon within the PNS can regenerate if ______. Multiple choice question. some dendrocytes remain
some neurilemma remains
In retrograde transport, substances are moved ______ the cell body.
toward
Vesicles involved in retrograde transport are moving ______ the cell body.
toward
If a subthreshold value is reached on an axon membrane, an action potential ______.
will not occur
