LS 12
A flow of electrical current called an _________ ___________ is generated within the initial segment of a neuron
action potential
The __________ of the functional division of the nervous system provides involuntary control of smooth muscle
autonomic motor
The postsynaptic potential immediately follows the binding of neurotransmitter molecules that can
be both excitatory and inhibitory
The somatic sensory division detected stimuli that are __________ detected
consciously
The epineurium is made of _________ connective tissue
dense irregular
The tissues that receive nerve impulses from motor neurons are called
effectors
A difference in the number of charged particles between two sides of membrane forms a
electrical gradient
The electrochemical gradient is formed from a combination of the ________ gradient and the _________ gradient
electrical, chemical
A ______ is a cluster of neuron cell bodies with the peripheral nervous system
ganglion
The sensory division of the nervous system is responsible for
input
charged particles
ions
Type B
medium conduction velocity
voltage
membrane potential
The resting membrane potential is measured in ___________
millivolts
__________ neurons are most common
multipolar
The presence of a ________ sheath increases the rate of impulse conduction
myelin
In neurons, most chemically gated ion channels open in response to the binding of a
neurotransmitter
The neuron cell body hoses both the ________ and the cytoplasm
nucleus
bipolar neurons have one axon and ______ dendrite
one
The motor nervous system is responsible for ________
output
A fascicle is surrounded by a layer of dense irregular connective tissue called _______
perineurium
resistance
plasma membrane
A graded potential that occurs in a postsynaptic neuron is known as a
postsynaptic potential
The sequential opening of voltage-gated sodium channels is followed by the sequential opening of voltage-gated ________ channels
potassium
intracellular
potassium, organic anions
A return of the membrane potential towards the resting membrane potential immediately following depolarization is called
repolarization
The process by which postsynaptic potentials are added together at the initial segment is known as
summation
"An action potential either happens or it doesn't" This statement could also be called
the all-or-none law
In the initial segment, an action potential is generated if the membrane potential reaches the
threshold potential
Sensory nerves carry information
to the central nervous system
________ are NOT commonly found in receptive segment of a neuron
voltage gated ion channels
According to Ohms law, current is related to ________, and inversely directed to _______
voltage, resistance
Which of the following ions have leak channels on the plasma membrane
K+, Na+
A unipolar neuron has one extension. a bipolar neuron has ____ extensions
2
Place the events of synaptic transmission from earliest to latest
1 Action potential reaches synaptic knobs 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
Which of the following membrane transporters are present throughout the membrane of a neuron?
Na+/K+ pumps, sodium leak channels, potassium leak channels
If several EPSP's occur at different synapses, they undergo ________ at the initial segment.
Spatial summation
The refractory period occurs immediately ________ an action potential
after
Action potentials are always propagated along an axon at the same _______ but _______ can vary depending on the strength of the stimulus
amplitude, frequency
A substance synthesized at the cell body must undergo________ transport to reach the synaptic knobs
anterograde
_________ neurons have a single, short neuron process that emerges from the cell body and branches like a T.
Unipolar
________ are unique channels in that they have three states; resting, activation, and inactivation
Voltage-gated channels
The plasma membrane of an axon is called the
axolemma
Extracellular ions
chloride, sodium
Type A
conduction velocity up to 150 meters per second
The main activity of the _______ is propagation of an action potential along the axolemma.
conductive segment
________ nerves extend from the brain, while _______ nerves extend from the spinal cord
cranial, spinal
An individual axon is wrapped in a connective tissue covering called the
endoneurium
The "E" is EPSP stands for __________, meaning that the potential makes the inside of the postsynaptic cell more __________
excitatory, positive
When chemically or voltage gated channels open, there is a change in ion _______ across a membrane
flow
current
flow of ions through the ion channels
If you were moving across a neurons membrane from the receptive segment toward the transmissive segment, in the _________ is where you would first encounter large numbers of voltage-gated Na+ and K+ channels
initial segment
The brain interprets the increased frequency of nerve signals as a ________ stimulus
more intense
The opposite to the movement of electrical charge is known as
resistance
Interneurons facilitate communication between ________ neurons and ________ neurons
sensory and motor
________ are found in mixed nerves
sensory and motor axons
which of the following are functional classes of neurons?
sensory neurons, motor neurons, interneurons
Which of the following are considered types of effectors?
skeletal muscle, cardiac muscle, glands
Type C
slowest conduction velocity
The flow of _______ ion is the most common cause of depolarization
sodium
___________ are voltage-gated ion channels that have two gates
sodium channels
Which two are divisions of the sensory nervous system
somatic division and visceral division
If several EPSP's occur at different synapses, they undergo ________ at the initial segment
spatial summation
A change in membrane potential insufficient to cause an action potential is known as a
subthreshold value
The components of the somatic sensory division are
taste, joints and muscles, hearing
If several EPSP's occur at a synapse over a short period of time, they undergo _________ at the initial segment
temporal summation
Which of the following segments of a neuron contain large numbers of voltage-gated potassium channels and voltage-gated sodium channels?
the initial segment and conductive segment
In the initial segment, an action potential generated if the membrane potential reaches the
threshold value
Dendrites transfer information ________ the cell body
toward
Voltage-gated calcium channels are found mostly in the _________ segment
transmissive
True or False: Most voltage-gated ion channels are closed ion channels are closed until the electrical potential across a membrane changes
true
Most channels have ____ gates, but a sodium channel has ______ gates
two, three
Most afferent neurons are classified functionally as
unipolar
The _________ division of the nervous system detects nerve impulses from blood vessels and internal organs
visceral sensory division
_____________ are membrane molecules that use the energy of ATP to move ions against a concentration gradient
Pumps
_________ is a typical resting membrane potential for a neuron
-70 millivolts
____________ is a type of membrane transport protein that increases the potential energy across a membrane
A pump