The efferent division of the peripheral nervous system innervates: smooth muscle cells
skeletal muscle cells
heart muscle cells
All of the answers are correct.
All of the answers are correct
________ neurons are small and have no anatomical features that distinguish dendrites from axons.
Most CNS neurons lack centrioles. This observation explains
why CNS neurons cannot divide to regenerate damaged tissue
Functions of astrocytes include all of the following, except
maintaining the blood-brain barrier.
forming a three-dimensional framework for the CNS.
conducting action potentials.
responding to neural tissue damage.
guiding neuron development.
conducting action potentials
What are the functions of astrocytes in the CNS?
Guiding neuron development
repairing damaged neural tissue
adjusting the composition of the interstitial fluid
maintaining the blood brain- barrier
Many medications introduced into the bloodstream cannot directly affect the neurons of the CNS because
the endothelium of CNS capillaries forms a blood-brain barrier
In the peripheral nervous system, Schwann cells participate in the repair of damaged nerves by
forming a cellular cord that directs axonal re-growth
At the normal resting potential of a typical neuron, its sodium-potassium exchange pump transports
3 intracellular sodium ions for 2 extracellular potassium ions.
Voltage-gated channels are present
moves sodium and potassium opposite to the direction of their electrochemical gradients.
________ channels open or close in response to physical distortion of the membrane surface.
If the sodium-potassium pumps in the plasma membrane fail to function, all of the following occur, except
the intracellular concentration of potassium ions will increase
If acetylcholine (ACh) causes inhibition of a postsynaptic neuron, to what type of membrane channel did the ACh bind?
chemically-regulated potassium channel
If the axolemma becomes more permeable to potassium ion:
a stronger stimulus will be required to cause an action potential
In what part of the neuron does the action potential typically initiate?
initial segment of the axon
During an action potential of a neuron, what directly causes the different channels to open and close?
the transmembrane potential (voltage)
What ion is responsible for the depolarization of the neuron during an action potential?
What type of membrane transport causes the depolarization phase of the action potential in neurons?
Where are action potentials regenerated as they propagate along an unmyelinated axon?
at every segment of the axon
The movement of what ion is responsible for the local currents that depolarize other regions of the axon to threshold?
sodium (, sodium (Na+)
Approximately how fast do action potentials propagate in unmyelinated axons in humans?
1 meter per second
In contrast to the internodes of a myelinated axon, the nodes __________.
have lower membrane resistance to ion movement.
The node-to-node "jumping" regeneration of an action potential along a myelinated axon is called __________.
How do action potential propagation speeds in myelinated and unmyelinated axons compare?
Propagation is faster in myelinated axons.
The all-or-none principle states that
all stimuli great enough to bring the membrane to threshold will produce identical action potentials.
If the chemically-gated sodium channels in the postsynaptic membrane were completely blocked,
Synaptic transmission would fail
Which of the following is not a possible drug effect on synaptic function?
change the type or receptor found in the postsynaptic membrane