Physio Ch 7 Nervous System 12th ed
Muscarinic ACh receptors act through ____________ activation of K+ channels.
G-protein
Benzodiazepines act by increasing ________ activity.
GABA
Spatial summation
occurs because of the convergence of many neurons on a single postsynaptic cell
The mechanism that allows many Na+ ions to move into the axon is
positive feedback.
The membrane of resting nerve cells is more permeable to ____________ ions than ____________ ions.
potassium, sodium
If the binding of muscarine to its receptor in the heart causes the beta-gamma complex of the G-protein to bind to a K+ channel,
the K+ channel will open, leading to hyperpolarization and inhibition
In a myelinated axon, Na+ channels are
concentrated at the nodes of Ranvier.
Ion channels that open in response to depolarization are called
voltage-gated channels.
Fetal neuron growth requires the actions of a group of chemicals known as
neurotrophins.
Addictive drugs, as well as nicotine, activate dopamine release in the
nucleus accumbens
The average resting membrane potential of an axon is
-70mV.
Postsynaptic inhibition is caused by
GABA and glycine
The most common neurotransmitter in the brain is
GABA.
Both long-term potentiation and long-term depression requires release of ___ from the postsynaptic neuron membrane
Ca2+
Acetylcholine can induce hyperpolarization by
binding to muscarinic receptors
Local anesthetics block conduction of action potentials in sensory neurons by
binding to sodium channels.
Synaptic plasticity involves structural changes in neurons such as
formation of dendritic spines
Degeneration of spinal motor neurons in adults may be due to a lack of ____________ factor.
glial-derived neurotrophic (GDNF)
Mutation of the N-methyl-D-aspartate (NMDA) receptor would affect the ability of ____________ to regulate neural function
glutamate
Excitatory postsynaptic potentials are produced by
glutamic acid
Chemical synapses
have a delayed impulse transmission.
Which of the following is NOT classified as a catecholamine?
histamine
Where is glycine released?
in the CNS
What causes presynaptic inhibition?
inactivation of Ca2+ channels, a second neuron causes a reduction in neurotransmitter release from another neuron, axoaxonic synapses
What coding system do neurons use to get a greater response?
increased frequency of stimuli
Catecholamines activate postsynaptic cells by
increased production of cyclic AMP
Inhibition of neuropeptide Y synthesis would
inhibit eating
At what region of the neuron are action potentials first produced?
initial segment of an axon
Which of the following is NOT true of axonal transport?
is a passive process
What process occurs when glutamate-releasing presynaptic neurons stimulate postsynaptic release of endocannabinoids that acts as retrograde neurotransmitters?
long-term depression
Enhancing the excitability of a synapse so that transmission is favored along certain
long-term potentiation
The mesolimbic dopamine neurons arise in the midbrain and terminate in the
nucleus accumbens
Temporal summation
occurs when a single neuron releases neurotransmitter rapidly
The myelin sheaths of CNS neurons are produced by
oligodendrocytes.
What action produces an IPSP on the postsynaptic membrane?
opening of Cl- channels into the neuron
Which of the following is true of axons?
originates at the axon hillock on the cell body
Which ion's movements is responsible for repolarization?
outward diffusion of K+
What type of autonomic fibers release ACh at effectors?
parasympathetic
Which of the following is NOT a function of astrocytes?
phagocytose foreign material in the CNS
The ability of a neuron to transmit charge through its cytoplasm is called cable properties and is very
poor.
An axon will depolarize only if the membrane potential reaches between -70mV and -55mV. This follows the
All-or-none law.
Which of the following is NOT true of long-term potentiation (LTP)?
Associated with the removal of AMPA glutamate receptors
______ synapses occur between axons of presynaptic cells and dendrites of postynaptic cells.
Axodendritic
The binding of a neurotransmitter to its receptor protein causes ion channels to open in the post-synaptic membrane. What type of gates are these?
Chemically-regulated gates and ligand-regulated gates are correct.
Which of the following is NOT an action needed for glutamate to open ion channels?
Cl- must pass through the open channel
Hyperpolarization in the postsynaptic cell is caused by
Inhibitory postsynaptic potentials and movement of K+ out of the cell are correct.
What type of neuron is found entirely in the CNS?
Interneuron and association neuron are correct
Blocking ____________ channels would prevent neuron depolarization.
Na+
What is NOT true of the relative refractory period?
Na+ channels are inactivated
During an action potential
Na+ influx causes depolarization.
What process is needed to return a membrane to its resting membrane potential with all ions in the correct locations?
Na+/K+ pump
____________ is an acetylcholinesterase antagonist used to treat myasthenia gravis
Neostigmine
Which of the following is NOT true of nicotinic-gated channels?
Only action potentials are generated.
The period of time when Na+ channels are recovering from their inactive state and K+ channels are still open is the
Repolarization and relative refractory period are correct.
Synaptic vesicles are docked to the plasma membrane of the axon terminal by a protein complex called
SNARE.
Action potential transmission in the PNS is decreased if which cells are damaged?
Schwann cells
The myelin sheaths of PNS neurons are produced by
Schwann cells.
What do muscarine and nicotine have in common?
They are both agonists for their respective receptors.
What medication acts by increasing the action of nitric oxide as a treatment for erectile dysfunction?
Viagra
Action potentials would be conducted most rapidly by
a 40 mm diameter myelinated axon.
Botulism toxin prevents release of ACh, causing
flaccid paralysis.
Cholinergic fibers use ____ as the neurotransmitter
acetylcholine
Which of the following is NOT true of histamine?
acts as a neurotransmitter in the brain to cause drowsiness
What is the action of the binding of muscarine to its receptors in the digestive system?
alpha subunits bind to K+ channels, close them, leading to depolarization
Sensory neurons
are pseudounipolar and carry impulses toward the CNS
The blood-brain barrier results mostly from the action of __________, a type of glial cell.
astrocytes
Which cells are needed for the formation of synapses in the CNS?
astrocytes
The most numerous of all cells of CNS nervous tissue are the
astrocytes.
Which division of the nervous system innervates involuntary effectors?
autonomic nervous system
Neurotransmitter release would be inhibited by
blocking Ca2+ influx in the axon terminal.
ATP and adenosine can act as neurtransmitters
by being released from astrocytes, as cotransmitters, as paracrine regulators.
Acetylcholine
can bind to nicotinic receptors.
Gliotransmitters
can stimulate neurons.
Which of the following is NOT true of norepinephrine?
causes depression in the CNS
What type of proteins are present at chemical synapses to ensure the close proximity of the presynaptic and postsynaptic membranes?
cell adhesion molecules (CAMs)
The brain and spinal cord comprise the
central nervous system.
What type of proteins are present in gap junctions that form water-filled channels between neurons?
connexins
Which of the following effect(s) acetylcholine synaptic transmission?
curare and botulinum toxin.
What type of neural pathway involves one neuron forming synapses with several postsynaptic neurons?
divergent
Neuroleptics, which are used to treat schizophrenia, are
dopamine antagonists
The brain produces lipid neurotransmitters called
endocannabinoids
Which of the following are natural analgesics?
endorphins, enkephalins, dynorphins
Which type of cell lines the ventricles of the brain and help produce cerebrospinal fluid?
ependymal cells
Excitotoxicity is caused by
excessive synaptic release of glutamate
Endogenous cannabinoids have effects similar to the active ingredient in
marijuana
The __________ dopamine system may be involved in emotional reward and drug addiction
mesolimbic
Which type of cell of the CNS is phagocytotic?
microglia
Which of the following is NOT a structural classification of neurons?
motor neuron
Retrograde transport
moves toward the cell body, moves membranes, vesicles, and viruses, uses molecular motor proteins of dynein.
The disease ______________ is characterized by destruction of CNS myelin sheaths and the formation of hardened scars.
multiple sclerosis.
Which of the following is NOT a functional classification of neurons?
multipolar
Which of the following is NOT a type of glutamate receptor?
muscarinic receptor
Regeneration of CNS axons may be prevented in part by inhibitory proteins in the membranes of the
myelin sheath.
Axonal regeneration is inhibited by
myelin-associated inhibitory protein.
White matter is
myelinated axons in the CNS.
The normal effect of -endorphin can be blocked by
naloxone
Repolarization is accomplished through a
negative feedback loop.
What structure is found around PNS axons that is NOT found around CNS axons?
neurilemma
The most abundant neuropeptide in the brain is
neuropeptide Y
Chemicals that stimulate action potentials in postsynaptic cells are called
neurotransmitters.
Curare is a competitive ACh antagonist at _____________ ACh receptors
nicotinic
Acetylcholine usually induces an excitatory postsynaptic potential when binding to ________ receptors and an inhibitory postsynaptic potential when binding to some ____________ receptors.
nicotinic, muscarinic
Relaxation of cerebral blood vessels would be stimulated by excessive ________ activity.
nitric oxide
Which gas(es) can function as a neurotransmitter?
nitric oxide and carbon monoxide
The gap of exposed axon in the myelin sheath is the
node of Ranvier.
What type of receptors will bind ATP and adenosine?
purinergic receptors
As the intensity of a stimulus increases, more axons will become activated. This process is called
recruitment.
Which of the following is NOT a function of neurotrophins?
regeneration of injured motor neurons
Endocannabinoids are retrograde neurotransmitters, meaning they are
released from postsynaptic neurons and diffuse to the presynaptic neuron
Conduction of an action potential in a myelinated axon is called
saltatory conduction.
Cells supporting neuron cell bodies in ganglia are termed
satellite cells.
What neurotransmitter is used by neurons with cell bodies in the raphe nuclei along the midline of the brainstem?
serotonin
Muscarinic ACh receptors are found in all of the following locations EXCEPT
skeletal muscle
Nitric oxide
stimulates the dilation of blood vessels
What is the predominant affect of stimulation of nicotinic-gated channels?
stimulation due to influx of Na+ ions
Which poison inhibits glycine receptors?
strychnine
The capacity of synapses for alteration at the molecular level is termed as
synaptic plasticity
The varied strength of synaptic transmission is called
synaptic plasticity
What is NOT true of conduction through dendrites and cell bodies of neurons?
they are action potentials
Which of the following is NOT true of EPSPs?
they have a refractory period
The minimum depolarization needed to open Na+ gates is called the
threshold.
A bundle of axons in the CNS is called a/an
tract
Which of the following is NOT true of dendrites?
transmits action potentials toward the cell body
Serotonin is synthesized from the amino acid
tryptophan
MAO inhibitors may cause hypertensive crisis by a person eating foods rich in
tyramine
What amino acid are dopamine, norepinephrine, and epinephrine derived from?
tyrosine
Neurotransmitters
usually regulate ion channels.
What is present at the axon hillock that allows the production of action potentials?
voltage-gated channels