A&P Chapter 12 Connect
intracellular
organic ions
Neuron pools are also called
pathways and neuronal circuits
Typical cellular organelles like the endoplasmic reticulum, Golgi apparatus, ribosomes and mitochondria are found in the
perikaryon
A fascicle is surrounded by a layer of dense irregular connective tissue called
perineurium
resistance
plasma membrane
When sodium ions flow into a cell through a leak channel they make the membrane potential more
positive
A graded potential that occurs in a postsynaptic neuron is known as a
postsynaptic potential
Voltage is a measure of relative ______ energy.
potential
The removal of neurotransmitter from the synaptic cleft by transport into the synaptic knob is known as
reuptake
_______ nerves always relay information to the CNS.
sensory
Interneurons facilitate communication between ____ neurons and ____ neurons.
sensory; motor
An action potential cannot be initiated during the absolute refractory period because
sodium channels are inactivated, and thus can not open
The myelin sheath covers
the axon
axoplasm
the cytoplasm of the axon
The blood-brain barrier helps protect the brain from
toxins
Voltage gated calcium channels are found mostly in the _____ segment.
transmissive
To _______ is the basic function of a neuron
transmit nerve impulses
______ help return the membrane potential to the resting state following hyperpolarizaiton.
-Na/K pumps restore gradients -voltage gated potassium channels close
Identify all of the components of the central nervous system.
-brain -spinal cord
Synapses are classified as
-electrical synapses -chemical synapses
_____ of our neurons are interneurons
99%
______ correctly describes the role of K+ leak on the resting membrane potential.
As potassium flows out of a cell the inside of the cell becomes more negative
_______ occurs when the inside of the cell becomes more postive (less negative) than the resting membrane potential.
Depolarization
______ is an acronym which is used to describe a postsynaptic graded potential in which the membrane becomes more negative on the inside.
IPSP
Neurofibril nodes are also called nodes of
Ranvier
TF Facilitation and Inhibition may be caused by changes in either the presynaptic neuron or the postsynaptic neuron.
TRUE
TF In most cases, a single EPSP is not sufficient to cause a neuron to reach the threshold potential.
TRUE
The voltage gated sodium channels ______ during repolarization.
are inactivated
The voltage gated potassium channels _____ during repolarization.
are open
Dendrites branch off of the
cell body
axon
conducts information away from the cell body
The movement of charged particles is known as
current
monoamine
derived from certain amino acids
______ allow ions to pass from one neuron to the other.
electrical synapses
Synaptic knobs are also called
end bulbs and terminal boutons
A myelinated axon has a _______ conduction velocity than an unmyelinated axon.
faster
______ describes the propagation of depolarization down an axon.
flow of Na+ to downstream regions causes depolarization of adjacent regions
current
flow of ions through ion channels
Neuron cell bodies in the peripheral nervous system are found clustered in
ganglia
A(n) ________ is a cluster of neuron cell bodies with the peripheral nervous system.
ganglion
The autonomic nervous system is
involuntary
charged particles
ions
Type A
large diameter myelinated
voltage
membrane potential
_____ act as a phagocyte.
microglial cells
The resting membrane potential is measured in
millivolts
______ neurons are most common.
multipolar
The thin outer layer of the neurolemmocyte is called the
neurilemma
The intermediate filaments of a neuron are called
neurofilaments
______ are intermediate filaments that aggregate to form bundles called neurofibrils.
neurofilaments
The component of nervous tissue that conducts electrical impulses are
neurons
A flow of electrical current called a(n) _______ _______ is generated within the initial segment of a neuron.
action potential
The refractory period occurs immediately _____ an action potential
after
glutamate
amino acid
A substance synthesized at the cell body must undergo ______ transport to reach the synaptic knobs.
anterograde
Axon collaterals
are side branches off of an axon
The _____ is sometimes called the nerve fiber.
axon
Wallerian degeneration describes _____ degeneration in the ______ nervous system.
axon; peripheral
slow axonal transport results from the flow of
axoplasm
The synapse is located ______ the presynaptic neuron and the postsynaptic neuron.
between
The nervous system is composed of the ________, spinal cord, nerves, and ganglia.
brain
Amino acids
building blocks of proteins secreted as neurotransmitters
The _______ is the structural division of the nervous system that contains the brain.
central nervous system
The brain and spinal cord are part of the
central nervous system.
The ependymal cells help produce
cerebrospinal fluid
neuropeptide
chain of amino acids secreted as neurotransmitter
A positive change in the membrane potential is called
depolarization
In Wallerian degeneration the _____ portion of the axon degenerates.
distal
when chemically or voltage gated channels open, there is a change in ion ______ across a membrane
distribution
A message traveling from one presynaptic neuron to multiple postsynaptic neuron is an example of a ______ circuit.
diverging
The _____ receive impulses from the motor neurons.
effectors
An increase in the response of a postsynaptic neuron to a neurotransmitter is known as
facilitation
Primary CNS tumors typically originate in tissues that can undergo mitosis like which of the following?
glial cells and meninges
A ________ _________ is a temporary change in membrane potential which lasts only as long as the stimulus that causes it and can vary in size.
graded potential
The chromatophilic substace helps create the _______ color in parts of the brain and spinal cord.
gray
The _______ the resistance, the ________ the current.
higher; lower
The sensory division of the nervous system is responsible for
input
_____ is NOT a property of ation potentials.
intensity of an action potential varies depending on conditions
Norepinephrine
monoamine
The _______ consists of all axons that transmit a nerve impulse from the CNS to a muscle or gland.
motor nervous system
The presence of a _____ sheath increases the rate of impulse conduction.
myelin
A(n) ______ is much more efficient because saltatory conduction occurs and less energy is required to maintain the RMP.
myelinated axon
_____ is the name of the glial cell surrounding the axon.
neurolemmocyte
The ability to alter a response of neurons to neurotransmitters is known as
neuromodulation
A toxin which interferes with the activity of neurons is called a
neurotoxin
______ are chemicals released from synaptic knobs and bind to receptors on postsynaptic membranes.
neurotransmitter
The neuron cell body houses both the _____ and the cytoplasm.
nucleus
______ are large cells that ensheath many different axons.
oligodendrocytes
bipolar neurons have one axon and _____ dendrite.
one
Most channels have _______ gate(s), but a sodium channel has _______ gates.
one; two
A nerve is part of the ______ nervous system.
peripheral
The somatic _____ division of the nervous system receives information from the eyes, ears, and skin.
sensory
Receptors detect changes in the external or internal environment. These changes are called
stimuli
A change in membrane potential insufficient to cause an action potential is known as a
subthreshold value
neurons integrate multiple synaptic inputs by the process of
summation
The junction between an axon and another cell is called a
synapse
If several EPSPs occur at a synapse over a short period of time, they undergo ______ at the initial segment.
temporal summation
axon hillock
triangular region connecting the axon to the cell body
If an analogy is drawn between an action potential and shooting a gun, then the initial segment is analogous to the
trigger
The _________ functional division of the nervous system transmits information from the viscera to the central nervous system.
visceral sensory division
_____ are NOT commonly found in the receptive segment of a neuron.
voltage gated ion channels
_______ occurs when the inside of a cell becomes more negative than the resting membrane potential.
Hyperpolarization
Which of the following ions have leak channels on the plasma membrane?
K+ and Na+
The nerve impulse has the voltage gated ______ channels opened first followed by the opening of the voltage gated _____ channels.
Na then K
Place the events of a chloride-based IPSP in order from earliest to latest
1. inhibitory neurotransmitter binds to postsynaptic chemically gated chlorine channels 2. chloride moves from outside the cell to the inside 3. the inside of the postsynaptic cell becomes more negative 4. the local chloride current becomes weaker as it moves away from the neurotransmitter binding site
The voltage gated sodium channels undergo changes in activity during the depolarization phase of an action potential. Place these in order from first to last.
1. the membrane potential is -70 mv 2. sodium ions flow into the neuron 3. the membrane potential becomes more positive 4. voltage gated sodium ion channels open
______ are the most common.
Chemical synapses
Initially the voltage gated Na channels are closed and the membrane potential is _______ mv. As Na flows in the membrane potential changes to _____mv and threshold is reached.
-70/-55
If only K+ leak channels were present, the membrane potential would be
-90 mv
Which of the following are reasons for the very limited regeneration of damaged axons in the central nervous system?
-axons are crowded in the CNS -astrocytes create scar tissues inhibiting growth
Which of the following pumps can you find in the plasma membrane?
-calcium -sodium/potassium
Which of the following are considered types of effectors?
-cardiac muscle -skeletal muscle -glands
Which of the following are among the general characteristics of graded potentials?
-decrease intensity with distance traveled along membrane -can either be depolarizing or hyperpolarizing -degree of change in membrane potential is dependent of the stimulus magnitude
Which of the following are characteristics of neurons?
-extreme longevity -excitability -conductivity -secretion -amitotic
The components of the somatic sensory division are
-hearing -taste -joints and muscles
The functions of astrocytes are to
-help form the blood brain barrier -assist neuronal development -regulate the composition of interstitial fluid
Which of the following are functional classes of neurons?
-interneurons -sensory neurons -motor neurons
Which of the following conditions can make a PSP larger?
-more transmitter is released -more postsynaptic channels open
Which diseases are affected by destruction of the myelin sheath?
-multiple sclerosis -gullain-barre syndrome
Which of the following are structural classifications of neurons?
-multipolar -unipolar -bipolar
Synapses occur where axons contact which of the following?
-muscle cells -gland cells -other neurons
Choose the cells that are part of the central nervous system.
-oligodendrocyte -astrocyte -ependymal cells -microglia
Which of the following would be likely to cause hyperpolarization of a neuron?
-opening of a chemically gated chloride channel -opening of a voltage gated potassium channel
Which of the following would be likely to cause depolarization of a neuron?
-opening of a chemically gated sodium channel -opening of a voltage gated sodium channel
Which of the following membrane transporters are present throughout the membrane of a neuron?
-potassium leak channels -sodium leak channels -Na/K pumps
Which of the following processes are occuring during the synaptic delay?
-release of neurotransmitter -diffusion of neurotransmitter -binding of neurotransmitter to receptors
Which of the following segments of a neuron contain large numbers of voltage-gated potassium channels and voltage-gated sodium channels?
-the conductive segment -the initial segment
Two factors that affect PNS regeneration are:
-the distance between injury and the effector organ -the amount of damage
What must happen in order for a chemical signal to change the membrane potential of a neuron?
-there must be a charge in ion flow across the membrane -there must be a change in the number of open ion channels
Which of the following are true of neurolemmaocytes?
-they are also called Schwann cells -they create the myelin sheath in the PNS
Place the events of synaptic transmission from earliest to latest
1. action potential reaches synaptic knob 2. voltage-gated calcium channels open 3. calcium enters the synaptic knob 4. calcium triggers exocytosis of vesicles 5. neurotransmitter diffuses across synaptic cleft 6. neurotransmitter binds to postsynaptic receptors
Place the events of EPSP in order.
1. excitatory neurotransmitter binds to chemically gated cation channel 2. more Na+ enters the postsynaptic cell than K+ leaves 3. the inside of the cell becomes more positive 4. the local current of Na+ becomes weaker as it moves towards the axon hillock
TF Ion channels use the energy of ATP to maintain concentration gradients across neuron membranes.
FALSE
TF neurons far outnumber glial cells
FALSE
________ is an autoimmune disease causing destruction of the myelin sheath in the central nervous system.
Multiple sclerosis
TF In saltatory conduction, Na only flows across the axon membrane at the neurofibril nodes.
TRUE
TF The flow of potassium ions through leak channels makes the membrane potential more negative.
TRUE
TF The nervous system serves as the body's primary communication and control system.
TRUE
TF There are more potassium leak channels in a neuron membrane than sodium leak channels.
TRUE
TF most voltage-gated ion channels are closed until the electrical potential across a membrane changes.
TRUE
glycine
amino acid
Local _______ like lidocaine work by inhibiting impulse propagation along nerves.
anesthetics
Substances that can be moved in fast axonal transport (in)
anterograde and retrograde directions
The endoneurium is made of
areolar connective tissue
The presence of _______ ions causes the synaptic vesicles to bind to the membrane, causing neurotransmitters to be released.
calcium
Satellite cells are found surrounding
cell bodies
A _____ is best described as a channel that is usually closed that open in response to binding a neurotransmitter and that when open, allow a specific type of ion to diffuse across the plasma membrane.
chemically gated channel
Ependymal cells produce and circulate cerebrospinal fluid. The _______ helps circulate the CSF.
cilia
type b
conduction velocity of approximately 15 meters per second
The main activity of the ______ is propagation of an action potential along the axolemma.
conductive segment
dendrites
conducts information to the cell body
The somatic sensory division detects stimuli that are _____ detected.
consciously
____ occurs in an unmyelinated axon.
continuous conduction
The peripheral nervous system is made of the spinal nerves, ganglia, and _____ nerves.
cranial
_______ nerves extend from the brain, while ______ nerves extend from the spinal cord.
cranial; spinal
If Ohms law is rearranged to Voltage = "A" X Resistance, the term "A" should be
current
The electrical gradient in a resting neuron is such that the ______ of the cell is negative relative to the _______.
cytosol; outside
Another way for the neurotransmitter to be removed from the synaptic cleft is by _____ where there is uptake by surrounding glial cells.
diffusion
Parallel-after-_______ circuits have several neurons processing the same information at one time.
discharge
Motor neurons are classified as ______ neurons.
efferent
The motor nervous system is also referred to as the _______ division.
efferent
Creating and transmitting _____ currents is central to the function of neuron physiology.
electrical
The electrochemical gradient is formed from a combination of the _______ gradient and the _____ gradient.
electrical; chemical
neuropeptide
enkephalin
inactivation state
entry of sodium is prevented, activation gate is open
resting state
entry of sodium is prevented; activation gate is closed
An entire nerve is surrounded by a connective tissue covering called the
epineurium
The "E" in EPSP stands for ________, meaning that the potential makes the inside of the postsynaptic cell more ________.
excitatory; positive
Glial cells are found
in both the central and peripheral nervous systems
The changes in membrane potential associated with both EPSP and IPSP inputs are "added" in the _________ to determine if an action potential is initiated and the threshold is reached.
initial segment
dopamine
monoamine (biogenic amines)
The brain interprets the increased frequency of nerve signals as a _______ stimulus.
more intense
the sequential opening of voltage gated sodium channels is followed by the sequential opening of voltage gated ______ channels
potassium
propagation of depolarization only flow away from the cell body towards the synaptic knob because
previous regions in the axon have sodium channels in the inactive state
The period following an action potential in which an action potential can be initiated with a larger stimulus is known as the
relative refractory period
_____ is the return of polarity from positive back to negative (the RMP)
repolarization
some antidepressant drugs work by blocking the ______ of serotonin.
reuptake
Glial cells are both ______ than neurons and capable of ________.
smaller; mitosis
extracellular
sodium
activation state
sodium moves into the cell through the open channel
neuropeptide
somatostatin
If several EPSPs occur at different synapses, they undergo _____ at the initial segment.
spatial summation
The all or none law refers to the fact that action potentials will only occur if the initial segment reaches
threshold
Sensory nerves carry information
to the central nervous system
Most afferent neurons are classified functionally as
unipolar
pseudounipolar is another name for a ______ neuron.
unipolar
What are the two structural examples of sensory neurons?
unipolar and bipolar
type c
unmyelinated
The __________ division of the nervous system detects nerve impulses from blood vessels and internal organs.
visceral sensory division
______ is the typical resting membrane potential for a neuron.
-70 millivolts
