Chapter 12 PLQs
The resting membrane potential in neurons ranges from:
-40 to -90 mV.
Which type of axons has the largest diameter?
A fibers.
Plasticity means...
Ability to change based on experience.
This type of neuron has one dendrite and one axon emerging from the cell body.
Bipolar neuron.
During the resting state of a voltage-gated Na+ channel, 1. The inactivation gate is open. 2. The activation gate is closed. 3. The channel is permeable to Na+.
Both 1 and 2 are true.
The nervous system can distinguish between a light touch and a heavier touch by...
Changing the frequency of impulses sent to sensory centers.
An excitatory neurotransmitter _________ the postsynaptic membrane.
Depolarizes.
This type of neural circuit consists of a single presynaptic neuron synapsing with several postsynaptic neurons.
Diverging circuit.
Describe four ways drugs can modify the effects of neurotransmitters.
Drugs can modify neurotransmitter effects by: 1) stimulating or inhibiting their synthesis, 2) enhancing or blocking their release, 3) activating or blocking their receptor, and 4) stimulating or inhibiting their removal.
Schwann's cells begin to form myelin sheaths around axons in the peripheral nervous system...
During fetal development.
In the process of spatial summation, ______ are added together and _____ are subtracted from that total to determine whether _____ will be created at the trigger zone of the postsynaptic neuron.
EPSPs; IPSPs; action potentials
A postsynaptic neuron responds to neurotransmitters released by a presynaptic neuron by creating...
Either EPSPs or IPSPs.
Faster communication and synchronization are two advantages of...
Electrical synapses.
In temporal summation, a single presynaptic neuron stimulates the creation of action potentials in a postsynaptic neuron when it...
Fires at a fast enough rate that the sum of EPSPs in the postsynaptic neuron moves above threshold.
This type of nervous tissue contains neuronal cell bodies, dendrites, unmyelinated axons, axon terminals, and neuroglial cells.
Gray matter.
What factors limit neurogenesis in the CNS of adults?
Inhibitory influences from neuralgia, mainly from oligodendrites and the absence of growth stimulating cues present during fetal development.
A neurotransmitter that binds to an ionotropic receptor that contains a chloride channel would be classified as an...
Inhibitory neurotransmitter and would produce an IPSP in the postsynaptic neuron.
IPSP stands for...
Inhibitory postsynaptic potential.
In an action potential, the current that flows down the axon of a neuron is generated by the movement of ______ across the membrane.
Ions.
Na+/K+-ATPase is considered to be an electrogenic pump because...
It contributes to the negativity of the resting membrane potential.
Name the type of membrane channel that randomly opens and closes and is found in dendrites, cell bodies, and axons of all types of neurons.
Leak channel.
Name the type of membrane channel that opens in response to chemical binding and is found in dendrites of some sensory receptors like pain receptors, and in the dendrites and cell bodies of interneurons and motor neurons.
Ligand-gated channels.
A depolarizing graded potential...
Makes the membrane less polarized.
Name the type of membrane channel that opens in response to touch, pressure, vibration, or tissue stretching and is found in the auditory receptors of the ear, and in touch and pressure receptors in the skin.
Mechanically gated channels.
List the three ways that neurotransmitters can be removed from a synapse.
Neurotransmitters can be removed by: 1) diffusion, 2) enzymatic degradation or 3) uptake by cells.
Saltatory conduction...
Occurs only in myelinated axons.
During this period, a second action potential can only be initiated by a larger than normal stimulus.
Relative refractory period.
Diffusion, enzymatic degradation, and uptake by cells are all ways to...
Remove a neurotransmitter.
Describe the difference between spatial and temporal summation in a postsynaptic neuron.
Spatial summation is summation of postsynaptic potentials in response to stimuli that occur at different locations in the membrane of a postsynaptic cell at the same time. This typically occurs when multiple presynaptic neurons synapse with one postsynaptic neuron and fire simultaneously. Temporal summation is summation of postsynaptic potentials in response to stimuli that occur at the same location in the membrane of the postsynaptic cell but at different times. This typically occurs when one presynaptic neuron fires in rapid succession leading to a summing of the resulting EPSPs, which then triggers the generation of action potentials in the postsynaptic neuron as it moves above threshold.
List the three major factors that contribute to the creation of the resting membrane potential in excitable cells.
The major factors that lead to creation of resting potential are: 1) unequal distribution of ions across the plasma membrane, 2) inability of most anions to leave the cell, and 3) the electrogenic nature of the Na+,K+ -ATPase.
When the summed total of postsynaptic potentials rises above threshold, creation of action potentials occurs...
Tt the trigger zone.
Briefly describe the events that occur during the depolarizing phase of an action potential.
Voltage-gated Na+ channels open rapidly allowing Na+ to rush into the cell driven by both the electrical and chemical gradient. The inward rush of Na+ causes the membrane potential to become less negative, resulting in depolarization.
When a depolarizing graded potential makes the axon membrane depolarize to threshold,...
Voltage-gated Na+ channels open rapidly.
Name the type of membrane channel that opens in response to changes in membrane potential and is located in axons of all types of neurons.
Voltage-gated channels.
What specific type of unipolar neuron is shown in the diagram labeled B?
a) A Meissner corpuscle is a touch receptor that consists of a mass of dendrites enclosed by a capsule of connective tissue. b) A Merkel disc is a touch receptor that consists of free nerve endings (bare dendrites) that make contact with Merkel cells of the stratum basale of the skin. c) A pacinian corpuscle is a pressure receptor composed of a multilayered connective tissue capsule that encloses a dendrite. d) A nociceptor is a pain receptor that consists of free nerve endings (bare dendrites). Thermoreceptors (which detect thermal sensations), itch receptors, and tickle receptors resemble nociceptors in that they are unipolar neurons with free nerve endings that serve as sensory receptors.
What specific type of unipolar neuron is shown in the diagram labeled C?
a) A Meissner corpuscle is a touch receptor that consists of a mass of dendrites enclosed by a capsule of connective tissue. b) A Merkel disc is a touch receptor that consists of free nerve endings (bare dendrites) that make contact with Merkel cells of the stratum basale of the skin. c) A pacinian corpuscle is a pressure receptor composed of a multilayered connective tissue capsule that encloses a dendrite. d) A nociceptor is a pain receptor that consists of free nerve endings (bare dendrites). Thermoreceptors (which detect thermal sensations), itch receptors, and tickle receptors resemble nociceptors in that they are unipolar neurons with free nerve endings that serve as sensory receptors.
Which of the neurons is a touch receptor known as a Merkel disc?
a) A Meissner corpuscle is a touch receptor that consists of a mass of dendrites enclosed by a capsule of connective tissue. b) A Merkel disc is a touch receptor that consists of free nerve endings (bare dendrites) that make contact with Merkel cells of the stratum basale of the skin. c) A pacinian corpuscle is a pressure receptor composed of a multilayered connective tissue capsule that encloses a dendrite. d) A nociceptor is a pain receptor that consists of free nerve endings (bare dendrites). Thermoreceptors (which detect thermal sensations), itch receptors, and tickle receptors resemble nociceptors in that they are unipolar neurons with free nerve endings that serve as sensory receptors.
Which of the neurons is called a Meissner corpuscle or a corpuscle of touch?
a) A Meissner corpuscle is a touch receptor that consists of a mass of dendrites enclosed by a capsule of connective tissue. b) A Merkel disc is a touch receptor that consists of free nerve endings (bare dendrites) that make contact with Merkel cells of the stratum basale of the skin. c) A pacinian corpuscle is a pressure receptor composed of a multilayered connective tissue capsule that encloses a dendrite. d) A nociceptor is a pain receptor that consists of free nerve endings (bare dendrites). Thermoreceptors (which detect thermal sensations), itch receptors, and tickle receptors resemble nociceptors in that they are unipolar neurons with free nerve endings that serve as sensory receptors.
Which of the neurons is considered to be a bipolar neuron?
a) A Meissner corpuscle is a touch receptor that consists of a mass of dendrites enclosed by a capsule of connective tissue. b) A Merkel disc is a touch receptor that consists of free nerve endings (bare dendrites) that make contact with Merkel cells of the stratum basale of the skin. c) A pacinian corpuscle is a pressure receptor composed of a multilayered connective tissue capsule that encloses a dendrite. d) A nociceptor is a pain receptor that consists of free nerve endings (bare dendrites). Thermoreceptors (which detect thermal sensations), itch receptors, and tickle receptors resemble nociceptors in that they are unipolar neurons with free nerve endings that serve as sensory receptors.
Which type of unipolar neuron in the figure serves as a pain receptor?
a) A Meissner corpuscle is a touch receptor that consists of a mass of dendrites enclosed by a capsule of connective tissue. b) A Merkel disc is a touch receptor that consists of free nerve endings (bare dendrites) that make contact with Merkel cells of the stratum basale of the skin. c) A pacinian corpuscle is a pressure receptor composed of a multilayered connective tissue capsule that encloses a dendrite. d) A nociceptor is a pain receptor that consists of free nerve endings (bare dendrites). Thermoreceptors (which detect thermal sensations), itch receptors, and tickle receptors resemble nociceptors in that they are unipolar neurons with free nerve endings that serve as sensory receptors.
Which of the following types of neurons have one axon and one dendrite emerging from the cell body and are found in the retina of the eye, inner ear, and olfactory region of the brain? a) Bipolar neuron b) Multipolar neuron c) Unipolar neuron d) Nonpolarneuron e) Pseudounipolar
a) Bipolar neuron
In the diagram, where are axon terminals?
a) Dendrites b) Cell body c) Axon collateral d) Axon e) Neurolemma f) Axoplasm g) Axolemma h) Axon terminal i) Synaptic end bulb
In the diagram, where is the axon collateral?
a) Dendrites b) Cell body c) Axon collateral d) Axon e) Neurolemma f) Axoplasm g) Axolemma h) Axon terminal i) Synaptic end bulb
This part of a neuron contains the nucleus and cytoplasm of the Schwann's cell that has formed a myelin sheath around the axon.
a) Dendrites b) Cell body c) Axon collateral d) Axon e) Neurolemma f) Axoplasm g) Axolemma h) Axon terminal i) Synaptic end bulb
This part of the neuron contains the nucleus and Nissl bodies.
a) Dendrites b) Cell body c) Axon collateral d) Axon e) Neurolemma f) Axoplasm g) Axolemma h) Axon terminal i) Synaptic end bulb
Which part of the diagram is considered nerve fiber?
a) Dendrites b) Cell body c) Axon collateral d) Axon e) Neurolemma f) Axoplasm g) Axolemma h) Axon terminal i) Synaptic end bulb
Which of the following structures is labeled A in the diagram?
a) Dendrites b) Peripheral process c) Cell body d) Trigger zone e) Axon terminal
Which of the following structures is labeled B in the diagram?
a) Dendrites b) Peripheral process c) Cell body d) Trigger zone e) Axon terminal
Which of the following structures is labeled C in the diagram?
a) Dendrites b) Peripheral process c) Cell body d) Trigger zone e) Axon terminal
Which of the following structures is labeled D in the diagram?
a) Dendrites b) Peripheral process c) Cell body d) Trigger zone e) Axon terminal
Which of the following structures is labeled E in the diagram?
a) Dendrites b) Peripheral process c) Cell body d) Trigger zone e) Axon terminal
Which diagram represents a reverberating circuit?
a) Diverging circuit b) Converging circuit c) Reverberating circuit d) Parallel after-discharge
Which of the types of circuits is commonly used to send sensory signals to multiple areas of the brain?
a) Diverging circuit b) Converging circuit c) Reverberating circuit d) Parallel after-discharge
Which type of circuit is involved in solving mathematical problems?
a) Diverging circuit b) Converging circuit c) Reverberating circuit d) Parallel after-discharge
Which type of circuit is used to lengthen the output signal in physiological processes like regulation of the breathing pattern?
a) Diverging circuit b) Converging circuit c) Reverberating circuit d) Parallel after-discharge
Which of the channels shown in the figure opens and closes randomly?
a) Leak channel b) Ligand-gated channel c) Mechanically gated channel d) Voltage-gated channel
Which of the diagrams in the figure represents a ligand-gated channel?
a) Leak channel b) Ligand-gated channel c) Mechanically gated channel d) Voltage-gated channel
Which of these types of channels is involved in leaking sodium and potassium ions across the membrane in order to establish the resting potential of a cell?
a) Leak channel b) Ligand-gated channel c) Mechanically gated channel d) Voltage-gated channel
What is the structural classification of the neuron labeled A?
a) Multipolar neuron b) Bipolar neuron c) Unipolar neuron
What is the structural classification of the neuron labeled B?
a) Multipolar neuron b) Bipolar neuron c) Unipolar neuron
Which of the labeled cells in the diagram is a neuroglial cell that forms and maintains the myelin sheath around CNS axons?
a) Oligodendrocyte b) Microglial cell c) Neuron d) Fibrous Astrocytes e) Protoplasmic astrocyte f) Ependymal cell
Which of the labeled cells in the diagram is a neuroglial cell that is located mainly in gray matter and helps maintain the appropriate chemical environment for generation of nerve impulses?
a) Oligodendrocyte b) Microglial cell c) Neuron d) Fibrous Astrocytes e) Protoplasmic astrocyte f) Ependymal cell
Which of the labeled cells in the diagram is a neuroglial cell that is located mainly in white matter and helps maintain the appropriate chemical environment for generation of nerve impulses?
a) Oligodendrocyte b) Microglial cell c) Neuron d) Fibrous Astrocytes e) Protoplasmic astrocyte f) Ependymal cell
Which of the labeled cells in the diagram is a neuroglial cell that produces and assists in the circulation of cerebrospinal fluid?
a) Oligodendrocyte b) Microglial cell c) Neuron d) Fibrous Astrocytes e) Protoplasmic astrocyte f) Ependymal cell
Which of the labeled cells in the diagram is a neuroglial cell that removes debris and acts as a phagocyte?
a) Oligodendrocyte b) Microglial cell c) Neuron d) Fibrous Astrocytes e) Protoplasmic astrocyte f) Ependymal cell
Which of the labeled cells in the figure is NOT a neuroglial cell?
a) Oligodendrocyte b) Microglial cell c) Neuron d) Fibrous Astrocytes e) Protoplasmic astrocyte f) Ependymal cell
In the CNS, this structure is produced by oligodendrocytes.
a) Schwann cell b) Node of Ranvier c) Unmyelinated axons d) Schwann cell (nucleus) & cytoplasm e) Myelin sheath
In the diagram, the neuroglial cell that forms the myelin sheath around the axon is labeled...
a) Schwann cell b) Node of Ranvier c) Unmyelinated axons d) Schwann cell (nucleus) & cytoplasm e) Myelin sheath
In the diagram, where is a node of Ranvier?
a) Schwann cell b) Node of Ranvier c) Unmyelinated axons d) Schwann cell (nucleus) & cytoplasm e) Myelin sheath
This structure electrically insulates the axon of a neuron to increase the speed of nerve impulse conduction.
a) Schwann cell b) Node of Ranvier c) Unmyelinated axons d) Schwann cell (nucleus) & cytoplasm e) Myelin sheath
Which of the following neurotransmitters are used in virtually all of the inhibitory synapses found in the spinal cord? a) Gamma aminobutyric acid (GABA) and acetylcholine b) Gamma aminobutyric acid (GABA) and glycine c) Epinephrine and norepinephrine d) Serotonin and melatonin e) Glutamate and aspartate
b) Gamma aminobutyric acid (GABA) and glycine
Which of the following types of neurons is the most common type of neuron found in the brain and spinal cord? a) Bipolar neuron b) Multipolar neuron c) Unipolar neuron d) Nonpolar neuron e) Pseudounipolar
b) Multipolar neuron
Which of the following types of electrical signals allow rapid long-distance communication within the nervous system? a) Resting potential b) Nerve action potential c) Muscle action potential d) Graded potential e) Long-term potentiation
b) Nerve action potential.
With respect to neurons, the term "nerve fiber" refers to...
both axons and dendrites...
Chromatolysis refers to...
break up of Nissl bodies after neural injury.
Which of the following types of cells display the property of electrical excitability? a) Muscle cells b) Neurons c) All of these choices d) None of these choices
c) All of these choices.
Which of following organelles is a common site of protein synthesis in neurons? a) Mitochondria b) Nucleus c) Nissl body d) Golgi apparatus e) Nucleolus
c) Nissl body.
Which of the following types of neurons is exclusively found in the cerebellum? a) Bipolar neuron b) Multipolar neuron c) Purkinje cells d) Unipolar neuron e) Pyramidal cells
c) Purkinje cells
Which of the following is NOT a function of the nervous system? a) Sensory function b) Integrativefunction c) Motor function d) All are functions of the nervous system
d) All are functions of the nervous system.
Which of the following terms is used to describe a type of synapse? a) Axodendritic b) Axosomatic c) Axoaxonic d) All of the above choices e) None of the above choices
d) All of the above choices.
Which of the following are divisions of the peripheral nervous system? a) Somatic nervous system b) Autonomic nervous system c) Enteric nervous system d) All of these choices
d) All of these choices.
Which of the following is NOT considered a small molecule neurotransmitter? a) Acetylcholine b) Biogenicamines c) Purines d) Endorphins e) Serotonin
d) Endorphins.
Hearing your cell phone ring in an otherwise quiet lecture hall is an example of which of the following types of nervous system functions?a) Sensory function b) Integrativefunction c) Motor function d) More than one of the types of nervous system functions e) None of the types of nervous system functions
d) More than one of the types of nervous system functions.
Wallerian degeneration refers to...
degeneration of the distal end of axon and myelin sheath after neural injury.
A polarized cell... a) Has a charge imbalance across its membrane. b) Includes most cells of the body. c) Exhibits a membrane potential. d) Includes most cells of the body and exhibits a membrane potential. e) All of these choices are correct.
e) All of these choices are correct.
Which of the following is NOT a type of channel used in production of electrical signals in neurons? a) Leakage channel b) Voltage-gatedchannel c) Ligand-gated channel d) Mechanically gated channel e) Ion-gated channel
e) Ion-gated channel.
The motor portion of the autonomic nervous system can be divided into...
sympathetic and parasympathetic divisions.