A&P HW 11
This graph depicts a(n) __________.
EPSP
During an action potential, hyperpolarization is caused by:
K+ efflux
The cells that form the regeneration tube during neural regeneration are called __________.
Schwann cells
The brain and spinal cord compose the __________.
central nervous system
Depolarization to threshold during action potential propagation in axons is due to:
diffusion of Na ions down to the next segment of the axon
The step labeled 3 in the figure is __________.
motor output
Saltatory propagation occurs in _________ axons, in which action potentials _________.
myelinated; move from one node of Ranvier to another
If a neuron simultaneously receives a stimulus that results in local depolarization of 10 mV and a stimulus that results in a local hyperpolarization of 10 mV, the net effect would be:
no net change in membrane potential
Compared to chemical synapses, electrical synapses:
offer faster cell-cell communication
Myelin for an axon is analogous to:
rubber insulation for an electrical cable
This figure shows __________.
temporal summation
If a drug inhibits neurotransmitter receptors on the postsynaptic cells:
the neurotransmitter will have no effect in the postsynaptic cell
A neurotransmitter may have an excitatory or an inhibitory effect on the postsynaptic cell, depending on __________.
the receptor to which it binds
During an action potential, the rapid decrease in sodium ion permeability and the simultaneous and rapid increase in potassium ion permeability is responsible for __________.
the repolarization phase
What is the resting membrane potential of a typical neuron?
-70 mV
How many synaptic connections from different presynaptic neurons does an average neuron have?
10,000
What is the period during an action potential when a nerve fiber cannot be stimulated to produce an additional action potential no matter how strong the stimulus?
Absolute refractory period
Which of the following factors is associated with local potentials?
Also called graded potentials Reversible Decremental in nature
are star-shaped cells.
Astrocytes
Where are voltage-gated channels most abundant?
Axolemma
Which of the following terms does not refer to a structural type of synapse?
Axolemma
Where are synaptic vesicles located in a neuron?
Axon terminals of the presynaptic neuron
Which of the following structures can generate an action potential?
Axons
Which of these ions triggers exocytosis of synaptic vesicles
Ca2+
What ion triggers synaptic vesicles to release neurotransmitters into the synaptic cleft?
Calcium
Influx of which of the following ions can cause an inhibitory postsynaptic potential (IPSP) to be produced?
Chloride ions
List the following mechanisms for synaptic transmission termination?
Degradation of neurotransmitter by enzyme Reuptake of neurotransmitter into presynaptic neuron Diffusion of neurotransmitter away
are branched extensions off of a neuron.
Dendrites
Sodium ions are moving in, and the membrane potential is becoming less negative than the resting membrane potential.
Depolarization
What term refers to a temporary change in the cell's membrane potential that makes it less negative (or more positive)?
Depolarization
Which of the following events is most likely to trigger an action potential?
Excitatory postsynaptic potential (EPSP)
The red arrow is pointing to a(n) __________.
G-protein
Which of the following neurotransmitters is always inhibitory?
GABA
Which of the following features is not a structural component of chemical synapses?
Gap junction
Potassium ions are moving out, and the membrane potential is becoming more negative than the resting membrane potential.
Hyperpolarization
Which of the following causes the hyperpolarization phase of an action potential?
K+ outflow via voltage-gated potassium ion channels
What type of ion channel is always open?
Leak
Which type of channel opens in response to a chemical binding to a receptor on the channel?
Ligand-gated
are small, phagocytic cells in the central nervous system.
Microglia
Why is the resting membrane potential negatively charged?
More potassium ions leak out of the neuron than move in.
Which of the following mechanisms does not terminate the effects of a neurotransmitter?
Movement back to the cell body by retrograde axonal transport
Which of the following events will cause an EPSP?
Na ions enter postsynaptic cell
Depolarizing local potentials are caused by an influx of:
Na ions via gated ion channels
The Na+/K+ pump moves __________.
Na+ out of and K+ into the cell
What is the process of putting together all the excitatory and inhibitory stimuli that determine whether a neuron will or will not fire an action potential?
Neural integration
are the supporting cells of the nervous system.
Neuroglia
have fewer branches than astrocytes.
Oligodendrocytes
Which of the following terms refers to the neuron that delivers a message to a target cell?
Presynaptic
Potassium ions are moving out, and the membrane potential is becoming more negative as it moves back toward the resting membrane potential.
Repolarization
Which of the following characteristics is the fundamental process for most functions of the nervous system?
Synaptic transmission
Using the information provided in this graph, which statement best summarizes the activity in this neuron?
The cell gains positive charges, making the inside less negative.
List the events that occurs when the action potential is propagated along the axon?
The current continues to move down the axon, and the process repeats. The axolemma depolarizes to threshold as a result of local potentials. The next section of the axolemma depolarizes to threshold and fires an action potential as the previous section of the axolemma repolarizes.
Which of the following scenarios can increase the likelihood that a certain neuron will reach threshold and have an action potential?
There are equal amounts of EPSP's via spatial summation as there is temporal summation.
Which type of fiber has the largest diameter?
Type A
The neural circuit pattern in which the signal goes from several neurons to one is called __________.
a converging circuit
A bundle of axons in the PNS is called __________.
a nerve
A network of neurons that perform a common function is called __________.
a neuronal pool
The channel labeled 3 in the figure is __________.
a voltage-gated sodium ion channel in the inactivated state
During an action potential, when does sodium ion permeability begin to significantly decline?
at the peak of depolarization
Involuntary control of smooth and cardiac muscles and glands is provided by the __________.
autonomic nervous system
The conducting region of the neuron is the:
axon
What type of neuron is this?
bipolar
Which nervous system division is responsible for the integration of sensory information?
central nervous system
The two structural divisions of the nervous system are the:
central nervous system and peripheral nervous system.
The majority of synapses in the nervous system are:
chemical
What kind of conduction occurs when each section of the axolemma has to be depolarized to threshold in sequence along the entire axolemma for a current to spread down the length of the axon?
continuous
Action potential propagation in unmyelinated axons happens via:
continuous conduction
Which of the following is one of the mechanisms for termination of synaptic transmission?
degradation of neurotransmitter by enzyme
Multiple sclerosis is an autoimmune disease that destroys myelin in the CNS. Which of the following would be a symptom of multiple sclerosis?
delay in neural conduction
The short, branched cytoplasmic extensions that allow neurons to receive input signals are called __________.
dendrites
The influx of positive charges makes the membrane potential more positive and is known as __________.
depolarization
The influx of positive charges makes the membrane potential more positive and is known as:
depolarization
If a stimulus opens ligand-gated sodium ion channels, the neuron will __________.
depolarize
This figure depicts a __________.
diverging circuit
The neurotransmitter involved in emotion, motivation, and addictive behavior is __________.
dopamine
Bidirectional, instantaneous synaptic transmission is typical of __________.
electrical synapses
Which of the following moves the membrane potential of the postsynaptic neuron closer to threshold?
excitatory postsynaptic potential (EPSP)
Loss of K ions from the cytosol will have the same effect as:
gain of Cl ions
Which of the following is the most important excitatory neurotransmitter in the brain?
glutamate
The relative refractory period is caused by:
hyperpolarization
A series of measurements with a voltmeter show a neuron's membrane potential becoming more negative, from -70 mV to -85 mV. This neuron is experiencing a __________.
hyperpolarization phase
When voltage-gated sodium ion channels are inactivated, the neuron is _________________.
in the absolute refractory period
Batrachotoxin produced by certain species of frogs is a toxin that permanently opens voltage-gated Na ion channels. The results of exposure to batrachotoxin will be:
inability to generate action potentials
If a drug inhibits the enzyme Acetylcholinesterase, the effect will be:
increased ACh availability in synaptic cleft
Nicotine is addictive because it causes dopamine-releasing neurons to fire more action potentials. Nicotine will therefore cause:
increased levels of dopamine in the synaptic cleft
Neurons that relay information within the CNS and are the location of information processing are called __________.
interneurons
Conduction speed will be fastest in a __________.
large myelinated axon
Postsynaptic potentials are:
local potentials
The channel depicted in the figure is a __________.
mechanically gated channel
The small phagocytic cells that engulf debris and pathogens in the CNS are the __________.
microglia
The type of action potential propagation in which action potentials are only generated at nodes of Ranvier is called __________.
saltatory conduction
Simultaneous stimulation from multiple presynaptic neurons will result in __________.
spatial summation
List the following is a function of neurons?
transmitting motor information carrying sensory information integration
Which type of fiber has the slowest conduction speed?
type c
