chapter 12 nervous Flashcards
The nervous tissue outside of the central nervous system composes the ________ nervous system
peripheral
The ________ division of the peripheral nervous system brings sensory information to the central nervous system
afferent
The ________ division of the nervous system carries motor commands to muscles and glands.
efferent
The ________ nervous system provides involuntary regulation of smooth muscle, cardiac muscle, and glandular activity
autonomic
________ carry motor information to peripheral effectors
efferent
________ nerves are nerves that connect to the spinal cord
spinal
________ nerves are nerves that connect to the brain
cranial
________ monitor the position of skeletal muscles and joints
Proprioceptors
________ carry sensory information to the CNS
afferent neurons
________ provide information about the external environment.
exteroceptors
________ monitor the digestive, respiratory, cardiovascular, urinary, and reproductive systems
interceptors
The plasma membrane of an axon is called the
axolemma
The basic functional unit of the nervous system is the
neuron
The most common neuron of the nervous system is the
interneuron
Most neurons lack ________ and so are permanently blocked from undergoing cell division
centrioles
Products from the soma (cell body) of a neuron are transported to the synaptic terminals by ________ transport.
anterograde
A change in the conditions in the synaptic terminal can influence the soma as a result of ________ transport.
retrograde
Neuron cell bodies in the PNS are clustered together in masses called
ganglia
The tiny gaps between adjacent Schwann cells are called
nodes of ranvier
Regions of the CNS with an abundance of myelinated axons constitute the ________ matter.
white
Regions of the CNS where neuron cell bodies dominate constitute the ________ matter.
gray
A movement of charges in response to a potential difference is called
current
The separation of positive and negative charges across the membrane creates a ________ difference, or voltage.
potential
The sum of the electrical and chemical forces acting on an ion is known as its
electrochemical gradient
A shift of the resting transmembrane potential toward 0 mV is called
depolarization
The minimum stimulus required to trigger an action potential is known as the
threshold
The ________ principle states that the size and speed of the action potential are independent of the stimulus strength.
all or none
The period during which an excitable membrane cannot respond to further stimulation is the ________ period.
absolute refractory
The period during which an excitable membrane can respond again, but only if the stimulus is greater than the threshold stimulus, is the ________ period.
relative refractory
The presence of ________ dramatically increases the speed at which an action potential moves along an axon.
myelin
The sensory loss and muscle weakness associated with multiple sclerosis are a consequence of
demyelination
At a(n) ________ synapse, a neurotransmitter is released to stimulate the postsynaptic membrane.
chemical
In a(n) ________ synapse, current flows directly between cells
electrical
Compounds that alter the rate of neurotransmitter release by the presynaptic neuron or change the postsynaptic cell’s response to neurotransmitters are called
neuromodulators
The buildup of depolarization when EPSPs arrive in rapid succession is called ________ summation
temporal
The buildup of depolarization when EPSPs arrive at several places on the neuron is called ________ summation.
spatial
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.
After a stroke, what type of glial cell accumulates within the affected brain region?
microglia
Voltage-gated channels are present
in the membrane that covers axons
Which of the following is not involved in creating the resting potential of a neuron?
membrane permeability for sodium ions greater than potassium ions
When potassium channels open and the ions diffuse through the membrane,
the inside will become more negative
The following are the main steps in the generation of an action potential.
Sodium channels are inactivated.
Voltage-gated potassium channels open and potassium moves out of the cell, initiating repolarization.
Sodium channels regain their normal properties.
A graded depolarization brings an area of an excitable membrane to threshold.
A temporary hyperpolarization occurs.
Sodium channel activation occurs.
Sodium ions enter the cell and depolarization occurs
What is the proper sequence of these events?
4, 6, 7, 1, 2, 3, 5
The following are the steps involved in transmission at a cholinergic synapse. What is the correct sequence for these events?
Chemically-gated sodium channels on the postsynaptic membrane are activated.
Calcium ions enter the synaptic terminal.
Acetylcholinesterase hydrolyzes acetylcholine.
An action potential depolarizes the synaptic terminal at the presynaptic membrane.
The pre-synaptic terminal reabsorbs choline.
Acetylcholine is released from storage vesicles by exocytosis.
Acetylcholine binds to receptors on the postsynaptic membrane.
Calcium ions are removed from the cytoplasm of the pre- synaptic terminal.
4, 2, 6, 7, 1, 8, 3, 5
Which of the following is not a possible drug effect on synaptic function?
change the type of receptor found in the post synaptic membrane
Active neurons need ATP to support which of the following?
recovery from action potentials, the synthesis of neurotransmitter molecules, the movement of materials to the soma by axoplasmic transport, the movement of materials from the soma by axoplasmic transport
The rabies virus travels to the CNS via retrograde axoplasmic transport.
true
The axon hillock is a region between what two general regions of a neuron?
cell body and axon
Which neuroglia myelinate CNS axons and which neuroglia myelinate PNS axons?
oligodendrocytes; Schwann cells
Which part of an acetylcholine (ACh) molecule undergoes reuptake by the axon terminal to be reused in another acetylcholine molecule?
choline
Cholinergic synapses release the neurotransmitter
acetylcholine
Which part of the nervous system performs the higher-order thinking required to complete this practice exam?
central nervous system
Which of the following structures is NOT part of the PNS?
an interneuron within the spinal cord
What is included in the primary functions of the nervous system?
regulating and controlling peripheral structures and systems
providing sensation of the internal and external environments
integrating sensory information
Neurons are responsible for _________
information transfer and processing in the nervous system
The region of a neuron with voltage-gated sodium channels is the __________
axon
Neurons are classified on the basis of their structure as _________
anaxonic, unipolar, bipolar, and multipolar
Neurons are classified on the basis of their function as __________
motor, sensory, or association
What are the two major cell populations of neural tissue?
neurons and neuroglia
Which of the following CNS glial cells remove debris, wastes, and pathogens by phagocytosis?
microglia
The white matter of the CNS represents a region dominated by the presence of ________
oligodendrocytes
Depolarization of the membrane will shift the membrane potential toward _______
0
Depolarization of the membrane will shift the membrane potential toward _______
hyperpolarization
If resting membrane potential is –70 mV and the threshold is –60 mV, a membrane potential of –62 mV will ________
not produce an action potential
At the site of an action potential, the membrane contains _________
an excess of positive ions inside the membrane and an excess of negative ions outside the membrane
Which of the following statements about repolarization of an axon is FALSE?
repolarization occurs when sodium ion channels are open
A node along the axon represents an area where _______
there is an absence of myelin
Nerve cell bodies in the PNS are clustered together in masses called _____
ganglia
What are the most important factors that determine the rate of action potential conduction?
the prescence of myelin and the diameter of the axon
At an electrical synapse, the presynaptic and postsynaptic membranes are locked together at ________
gap junctions
Exocytosis and the release of acetylcholine into the synaptic cleft are triggered by _____
calcium ions flooding inside the synaptic terminal
An important neurotransmitter in emotional states and moods is ________
serotonin
An excitatory postsynaptic potential (EPSP) is ________
a graded depolarization produced by the arrival of a neurotransmitter
An inhibitory postsynaptic potential (IPSP) is a __________
a graded hyperpolarization produced by the arrival of a neurotransmitter
Rabies is a viral disease contracted from the bite of an infected animal. Rabies bypasses many immune system defenses by traveling in peripheral neurons to reach the CNS. Which method of transport is NOT used by the rabies virus to reach the CNS?
antretrograde flow
The reason that active neurons need ATP is to support __________
the movement of materials to and from the soma via axoplasmic flow
the synthesis, release, and recycling of neurotransmitter molecules
the recovery from action potentials
Sensory neurons are responsible for carrying impulses ______
to the CNS
Interneurons, or association neurons, differ from sensory and motor neurons in their _______
exclusive location in the brain and spinal cord
Efferent pathways consist of axons that carry impulses ________
away from the CNS
Graded potentials that develop on the postsynaptic membrane in response to a neurotransmitter are __________
postsynaptic potentials
The addition of stimuli occurring in rapid succession at a single synapse is _________
temporal summation
What type of gated channel opens or closes in response to distortion of the membrane?
mechanically gated channel
Interneurons are responsible for _________
analysis of sensory inputs and motor outputs
Sensory (ascending) pathways distribute information ________
from peripheral receptors to processing centers in the brain
Tyson decides to travel overseas but does not have all the required vaccines needed before he goes. While on his trip, he contracts diphtheria. Which type of glial cell is particularly at risk from this disease?
Schwann cells
Schwann cells are glial cells responsible for _________
myelinating axons in the PNS
What happens when a barrier prevents the movement of opposite charges toward one another?
a potential difference exists
Which of the following statements about the sodium-potassium pump is correct?
The activity of the sodium-potassium pump is needed after every action potential to restore resting potential.
Which of the following is a correct statement of the all-or-nothing principle?
A given stimulus either triggers a typical action potential or does not produce one at all.
During the relative refractory period, a larger-than-normal depolarizing stimulus can _________
bring the membrane to threshold and initiate a second action potential
Saltatory conduction conducts impulses along an axon _________
five to seven times faster than continuous conduction
In type C fibers, action potentials are conducted at speeds of approximately _________
2 mph
Which of the following is true of axons?
the larger the diameter of the axon, the faster the rate of transmission
Facilitation in the neuron’s transmembrane potential toward threshold results from what?
any shift that makes the cell more sensitive to further stimulation
summation of EPSPs
exposure to certain drugs, such as nicotine
Rachel decides to go swimming, but when she sticks her big toe into the water, she changes her mind because the water is too cold. The sensory neurons responsible for sending the message about the temperature of the cold water are _________
exteroceptors
The main functional difference between the autonomic nervous system and the somatic nervous system is that the activities of the ANS are _______
primarily involuntary (autonomic)
Lulu, who is 50 years old, decides she wants to receive Botox treatments. If Botox, short for botulism toxin, prevents the release of ACh from synaptic terminals, what effect should Lulu expect from having Botox injected into her facial muscles?
temporary paralysis in the injected facial muscles
What happens when depolarization to threshold occurs?
voltage gated sodium channels are opened
Emma is very excited because after taking up running several months ago, she has begun to experience the phenomenon called “runner’s high.” This is caused by the production of endorphins. What is the effect of the endorphins on Emma when she runs?
Endorphins are blocking the transmission of substance P, a neurotransmitter that sends information about pain to the CNS.
Which of the following is the most excitatory neurotransmitter in the brain and functions in learning and memory?
glutamate
Ann and Elise are two college students on an overseas vacation. Because they both love seafood, they stop at a restaurant in a coastal town for lunch. After dining on shellfish, they become very sick and have trouble breathing. What may have happened to Ann and Elise?
Any of the responses could be correct. TTX, STX, and CTX all block sodium ion channels, cause abnormal sensations, and interfere with muscle control.
