Which of the following structures is not part of the central nervous system?
brain, nerve, spinal cord, tract
a nerve
Myelinates nerve fibers in the cns
oligodendrocyte
Lines brain cavities
ependymal cell
Myelinates nerve fibers in the pns
schwann cells
cns phagocytes
microglia
Helps regulate the ionic composition of cns extracellular fluid
astrocyte
What type of current flows through the axolemma during the steep phase of repolarization?
chiefly a potassium current
Assume that an epsp is being generated on the dendritic membrane. which will occur?
a.specific Na+ channels will open
b.specific K+ channels will open
c.a single type of channel will open, permitting simultaneous flow of Na+ and K+.
d. Na+ channels will open first then close as K+ channels open.
I single channel will open permitting simultaneous flow of Na+ and K+
The velocity of nerve impulse conduction is greatest in?
a.heavily myelinated large diameter fibers
b.myelinated small diameter fibers
c.unnmyelinated small diameter fibers
d.unmyelinated large diameter fibers
heavily myelinated large diameter fibers
Chemical synapse are characterized by all of the following except?
a.the release of a neurotransmitter by the presynaptic membrane
b.postsynaptic membranes bearing receptors that bind neurotransmitters
c.ions flowing through protein channels from the presynaptic to the post synaptic neuron
d.a fluid filled gap separating the neurons
ions flowing through channels form the presynaptic to the postsynaptic neuron
Biogenic amine neurotransmitters include all of the following except?
a.norepinephrine
b.acetylcholine
c.dopamine
d.serotoni
acetylcoline
The neuropeptides that act as natural opiates are?
enkephalins
Inhibition of acetylcholinesterase by poisoning blocks neurotransmission at the neuromuscular junction because?
ACh is not degraded hence prolonged depolarization is is enforced on the postsynaptic cell.
The anatomical region of a multipolar neuron that has the lowest threshold for generating an AP (action potential) is the?
axon hillock
An IPSP is inhibitory because?
it hyperpolarizes the postsynaptic membrane
Impulses continue around and around a circuit until one neuron stops firing
reverberating
One or a few input ultimately influence large numbers of neurons
diverging
Many neurons influence a few neurons
converging
May be involved in exacting types of mental activity
parallel after-discharge