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