chapter 12: Nervous Tissue

Saltatory conduction means ______.

"leaping"

Inhibitory postsynaptic potentials (IPSPs) maybe result from which of the following? Select all that apply.

- Opening Cl- channels - Opening k+ channels

Which is most likely to be the threshold potential for a neuron?

-55

Which is most likely to be the resting membrane potential of a neuron?

-70 mV

Which numerical value is most likely to be the resting membrane potential of a neuron?

-70 mV

Select the four categories of neurotransmitters based on chemical composition.

-Acetylcholine -Neuropeptides -Monoamines -Amino acids

Which is true about signal conduction in myelinated axons?

-Action potentials are only generated at the nodes of Ranvier. -The signal moves more rapidly through the internodes than it does through the nodes of Ranvier.

Which statements are true about signal conduction along myelinated fibers?

-Action potentials occur only at the nodes of Ranvier. -There are few voltage-gated ion channels at the myelin-covered internodes and multiple channels at the nodes of Ranvier. -Ions can be exchanged with the ECF only at the nodes of Ranvier.

How do neuromodulators alter synaptic transmission?

-Adjusting the sensitivity of postsynaptic neurons to neurotransmitters -Increasing the release of neurotransmitters by presynaptic neurons -Altering the breakdown and/or reuptake of neurotransmitter

Which are properties of action potentials?

-All or none -Nondecremental (signal maintains amplitude) -Self-propagating

Which types of glial cells are found in the central nervous system?

-Astrocytes -Microglia -Ependymal cells -Oligodendrocytes

Long-term potentiation may be involved in long-term memory. The molecular changes that occur in long-term potentiation include which of the following?

-Binding of glutamate to NMDA receptors -Entrance of calcium into the dendrite -The release of nitric oxide which triggers more glutamate release

Which neurotransmitters are classified as neuropeptides?

-Cholecystokinin -Endorphins

Which are types of long-term memory?

-Declarative -Procedural

Which factors influence the speed of nerve signal conduction?

-Diameter of axon -Presence of myelin

Which would cause postsynaptic stimulation to end?

-Diffusion of neurotransmitter from the synaptic cleft into extracellular fluid -Reuptake of neurotransmitter into the presynaptic knob -Cessation of signals in the presynaptic nerve fiber -Enzymatic degradation of neurotransmitter in the synaptic cleft

Which are the principal types of neural circuits?

-Diverging circuit -Parallel after-discharge circuit -Reverberating circuit -Converging circuit

Which two organ systems are primarily responsible for coordinating the other bodily systems so as to maintain homeostasis?

-Endocrine system -Nervous system

Which neurotransmitters produce EPSPs?

-Glutamate -Aspartate

Which neurotransmitters are classified as amino acids?

-Glutamate -GABA

Which neurotransmitters produce IPSPs?

-Glycine -GABA

Which are characteristics of local potentials?

-Graded -Decremental

Which are true regarding the Na+-K+ pump?

-It accounts for about 70% of the energy (ATP) required by the nervous system. -It helps maintain the proper ion distribution across the membrane, compensating for ion leakage.

Which correctly describe axonal transport?

-It involves transport of proteins within the axon (i.e. synaptic knob enzymes or proteins that maintain the axolemma). -It is bidirectional (retrograde and anterograde transport).

Which are true regarding the absolute refractory period? Select all that apply.

-It refers only to a small patch of the membrane; other parts of the neuron can still be stimulated while a small area of it is refractory. -No stimulus of any strength will trigger a new action potential. -It occurs during the depolarization and repolarization phases of the action potential.

Which statements are true regarding the Na+-K+ pump?

-It requires the use of ATP. -It moves Na+ out of the cell and K+ into the cell. -It helps maintain the proper ion distribution across the membrane.

Which describes slow axonal transport?

-It works in a stop-and-go fashion. -It is used to renew worn-out axoplasmic components in mature neurons.

Choose the major cytoplasmic inclusions in a neuron.

-Melanin -Lipid droplets -Glycogen granules -Lipofuscin

List the three functional classes of neurons.

-Motor neurons -Interneurons -Sensory neurons

Increasing the intensity of a stimulus may increase which of the following? Select two answers from the list below.

-Number of activated neurons -Firing frequency of individual neurons

Which are common symptoms of Parkinson disease?

-Progressive loss of motor function -Slurred speech -Change in gait; smaller and slower steps

Which are symptoms of Alzheimer disease?

-Reduced attention span -Memory loss -Loss of the ability to talk or eat -Deterioration of personality

Match each point in the action potential to the corresponding description of voltage-gated sodium and potassium channel activity.

-Resting membrane potential----Both types of voltage-gated channels are closed. -Depolarization begins---- Voltage-gated Na+ channels open; voltage-gated K+ channels open more slowly -Repolarization begins ---- Voltage-gated Na+ channels inactivate; voltage-gated K+ channels remain open longer

Which are functions of astrocytes?

-Secrete nerve growth factors -Form blood-brain barrier -Convert blood glucose to lactate for neurons to use for fuel -Regulate chemical composition of tissue fluid

Which neurotransmitters are classified as monoamines?

-Serotonin -Epinephrine

Which are names for the cell body of a neuron?

-Soma -Neurosoma

The visceral motor division of the PNS is also called the autonomic division. Which of the following are functions of this division?

-Stimulating smooth muscle -Accelerating or decreasing heartbeat -Controlling gland secretion

Which of the following statements are true about sodium?

-The resting plasma membrane is much less permeable to Na+ than to K+. -Na+ is about 12 times as concentrated in the ECF as in the ICF.

Which three factors contribute the most to the formation of the negative resting membrane potential?

-There is a higher concentration of K+ in the intracellular fluid as compared to the extracellular fluid. -Outward K+ diffusion causes positive and negative charges to accumulate on either side of the membrane where they attract each other. -Open leak channels in the plasma membrane allow K+ to diffuse across the membrane, down its concentration gradient.

Which statements characterize neurotransmitters?

-They are synthesized by presynaptic neurons. -They are released in response to stimulation. -They bind to receptors and alter the physiology of the postsynaptic cell.

Which statements are true about Schwann cells?

-They assist in the regeneration of damaged nerve fibers. -They form the myelin sheath in the PNS. -They form the neurilemma.

Which statements are true regarding postsynaptic potentials?

-They include EPSPs and IPSPs. -They are caused by neurotransmitters. -They are changes in the membrane potential of the postsynaptic terminal of a chemical synapse.

Which are characteristics of neural pools?

-They may be concerned with a particular body function. -They consist of complex patterns of interneurons.

Indicate which of the following statements are true about signal conduction along unmyelinated fibers.

-Unmyelinated fibers have voltage-gated channels along their entire length. -A zone of depolarization excites voltage-gated channels immediately distal to the action potential.

List in chronological order the stages of regeneration of a nerve fiber.

1. Degeneration of axon and myelin distal to injury 2. Swelling of soma; dispersal of Nissl bodies 3. Sprouting of axon growth processes 4. Growth process enters regeneration tube 5. Reestablishment of synaptic contact

Indicate the order of events that are initiated in an adrenergic synapse, after norepinephrine binds to its receptor.

1. G protein dissociates from receptor protein2. G protein binds to adenylate cyclase3. adenylate cyclase is activated4. ATP is converted to cyclic AMP by adenylate cyclase5. cyclic AMP induces multiple effects in the cell

The nervous system plays an important role in maintaining homeostasis. List, in order, the basic steps that describe how the nervous system carries out this task.

1. Information received by sensory receptors is transmitted to the CNS 2. Information is processed and an appropriate response is determined 3.A command is issued to effectors such as muscles or glands

Place these events into the order in which they occur during a single action potential.

1. Local potential depolarizes membrane 2. Threshold is reached 3. Depolarization spike 4. Repolariztion 5. Hyperpolarization

Starting with a signal reaching the distal end of the presynaptic axon, indicate the correct order of events that occur during transmission at a cholinergic excitatory synapse.

1. Opening of calcium gates in synaptic knob as nerve signal arrives 2. Exocytosis of ACh; diffusion across synaptic cleft 3. biding of ACh to receptors on postsynaptic neuron 4. Opening of sodium gates on post-synaptic membrane allowing influx of sodium 5. Depolarization of postsynaptic plasma membrane

What is the approximate ratio of glial cells to neurons?

10:1

Alzheimer disease affects about ______ of the US population over the age of 65.

11%

Which best describes an electrical potential?

A form of potential energy that can produce current

The all-or-none law of action potentials states which of the following?

A neuron will fire at maximum voltage if a stimulus depolarizes it to threshold.

Unipolar neurons

A single process

A cholinergic synapse uses which of the following as its neurotransmitter?

Acetylcholine

Which term describes all neurons that carry signals towards the CNS?

Afferent

Which disease is associated with the anatomical findings shown in this picture: shrunken folds of cerebral tissue, neurofibrillary tangles and senile plaques containing beta-amyloid protein?

Alzheimer disease

The neurotransmitters glutamate and GABA are examples of which of the following?

Amino acids

Kinesin

Anterograde transport

Which type of cell plays a role in the establishment of the blood-brain barrier?

Astrocyte

Which process of a neuron is specialized for rapid conduction of nerve signals to structures relatively far away from the neuron cell body?

Axon

Which term applies to the small swellings at the distal end of the axon of a neuron that contain synaptic vesicles?

Axon terminals

Which term refers to the passage of proteins, organelles and other materials along an axon?

Axonal transport

Labeled line coding depends on which of the following?

Axons carrying sensory information to the brain are activated by specific types of stimuli.

What type of synapse is formed on the cell body of the postsynaptic neuron?

Axosomatic

Neurons that have one axon and one dendrite, such as olfactory cells, certain neurons of the retina, and sensory neurons of the inner ear, are classified as which of the following?

Bipolar

Substance P

Brain, small intestine, and pain-receptor neurons; mediates pain transmission.

Tetanic stimulation at a synapse is due to accumulation of which of the following in the synaptic terminal?

Calcium

Memories lasting for a few hours, such as remembering what someone said to you earlier in the day may involve posttetanic potentiation. This occurs because of which of the following?

Calcium remains in the synaptic knob elevated and a later signal releases a large burst of neurotransmitter.

Sensory (afferent) neurons do which of the following?

Carry signals to spinal cord and brain

What are the two major anatomical subdivisions of the nervous system?

Central and peripheral nervous systems

Cholecystokinin (CCK)

Cerebral cortex and small intestine; suppresses appetite.

At a GABA-ergic synapse, the postsynaptic receptor for the GABA neurotransmitter is which type of channel?

Chloride

This picture shows an inhibitory postsynaptic potential (IPSP). This is usually due to the opening of which type of ion channels?

Chloride or potassium

Which term refers to a synapse that releases acetylcholine from the presynaptic axon terminal?

Cholinergic

Which fundamental physiological property of neurons allows them to send signals quickly over long distances?

Conductivity

The respiratory center of the brain receives input from other parts (i.e from receptors for blood chemistry in arteries and stretch receptors in the lungs) to set a pattern of breathing. This is an example of which type of circuit?

Converging

The circuit in which several input nerve fibers synapse with fewer postsynaptic neurons is what type of circuit?

Converging circuit

Which term refers to the flow of charged particles from one point to another?

Current

_____ are the processes of a neuron that usually receive signals from other neurons.

Dendrites

During which part of the action potential do most voltage-gated sodium channels open?

Depolarization

Which term refers to the upward change in membrane potential during an action potential?

Depolarization

β-endorphin

Digestive tract, spinal cord, and many parts of the brain; secreted as a hormone by the pituitary; suppresses pain; reduces fatigue; may produce "runner's high".

A single motor neuron stimulating hundreds of skeletal muscle cells is an example of which type of circuit? Multiple choice question.

Diverging

Motor, or _____ , neurons carry signals away from the CNS and they lead to effectors (muscle and gland cells).

Efferent

In the earliest twentieth century, biologists assumed that all synaptic communication was _____ (instead of chemical) because neurons seemed to touch each other and communicated rapidly.

Electrical

Which are neuropeptides that act as analgesics (pain relievers)?

Enkephalins

In adrenergic synapses, a single NE molecule binding to a receptor can induce formation of many cAMPs. This results in activation of many enzymes that induce gene transcription and thus, production of multiple metabolic products. Which term refers to this process?

Enzyme amplification

Which glial cell produces and helps circulate cerebrospinal fluid?

Ependymal cells

List the fundamental physiological properties of neurons.

Excitability, conductivity, secretion

Enzyme amplification occurs at which type of synapse?

Excitatory adrenergic

True or false: All neurotransmitters have an excitatory effect.

False

True or false: Damaged nerve fibers in the CNS regenerate very fast whereas damaged nerve fibers in the PNS never regenerate.

False

True or false: Electrical synapses are able to integrate information and make decisions more rapidly than chemical signals.

False

True or false: Signal conduction is faster in unmyelinated axons because myelin increases the capacitance of the membrane.

False

True or false: The more synapses a neuron has, the lesser its information-processing capability.

False

True or false: Voltage-gated ion channels are completely absent in the internodes of myelinated axons.

False

The knotlike swelling in a nerve where neuron cell bodies are found is called a(n) _____ .

Ganglion

In electrical synapses, electrical signals move quickly from cell to cell through which of the following?

Gap junctions

______ cells protect the neurons and help them function.

Glial

Short-term memory allows you to remember things for up to how long?

Hours

Which type of memory is important as you read (e.g. remembering the previous words in a sentence)?

Immediate

Ependymal cells

In the CNS; line cavities of the brain and spinal cord; secrete and circulate CSF

Microglia

In the CNS; phagocytize microorganisms, foreign matter, and dead nervous tissue

Schwann cells

In the PNS; form neurilemma around all PNS fibers and myelin around most of them; aid in regeneration of damaged nerve fibers.

Satellite cells

In the PNS; surround somas of neurons in ganglia, provide electrical insulation, and regulate the chemical environment of neurons

The opposite of facilitation is presynaptic _____ . This is a mechanism in which one presynaptic neuron suppresses another one.

Inhibition

The trigger zone includes the axon hillock and the _____ segment, a region between the axon hillock and the first glial cell.

Initial

Which term refers to the segment of an axon between the axon hillock and the first glial cell?

Initial segment

Which type of neuron lies entirely within the CNS and carries out the integrative function of the nervous system?

Interneuron

Between the nodes of Ranvier are myelin-covered segments of axon encircled by Schwann cells. Which term refers to these segments?

Internodes

Electrical currents in neurons are due primarily to the flow of which of the following through gated channels?

Ions such as sodium and potassium

Slow axonal transport is always anterograde. What about fast axonal transport?

It can be either anterograde or retrograde.

At rest, K+ diffuses out of the cell through leak channels in the plasma membrane. Why does K+ diffusion result in a negative membrane potential?

It creates a slight local accumulation of K+ on the outside of the membrane relative to the inside.

Which of the following contributes to the development of the resting membrane potential in neurons?

K+ is more concentrated in the ICF than in the ECF.

Different sensory receptors in the skin respond to different types of stimuli. The brain can infer the type of stimulus detected by which nerve fibers are activated. What is this called?

Labeled line coding

The myelin sheath is composed mostly of which of the following?

Lipids

Inclusions found in neurons include "wear-and-tear" granules that form when lysosomes degrade worn-out organelles and other products. What is the name of the golden-brown pigment that they contain?

Lipofuscin

Which term refers to decremental changes in electrical potential along a dendrite or the soma?

Local potentials

Which type of memory can store the most information?

Long-term

Declarative and procedural memory are two types of what?

Long-term memory

Which may be the basis for learning and long-term memory at the neuronal level?

Long-term potentiation

The ability of synapses to change is called synaptic plasticity. Which term refers to the neuronal pathways formed during learning?

Memory traces

Which group of neurotransmitters are synthesized from amino acids by removal of the -COOH group?

Monoamines

Which division of the PNS carries signals from the CNS to glands and muscle cells?

Motor

What creates electrical currents in neurons?

Movement of ions through channels

Neurons with numerous dendrites and a single axon are structurally classified as which of the following?

Multipolar

What are the effectors of motor neurons?

Muscle and gland cells

The pathway of neurons within a neural pool is called its what?

Neural circuit

Which term describes the ability of neurons to process information, store and recall it, and make decisions?

Neural integration

Which term refers to the outermost layer of myelin, containing the nucleus and cytoplasm of the Schwann cell?

Neurilemma

Which alter synaptic transmission by adjusting the sensitivity of postsynaptic neurons to neurotransmitters or by affecting the breakdown and/or removal of a neurotransmitter?

Neuromodulators

Sensory, association and motor are the three classes of what?

Neurons

Cholecystokinin and substance P are examples of which type of neurotransmitter?

Neuropeptides

Stimulation of the postsynaptic neuron will end when nerve signals stop arriving at the presynaptic axon terminal or when which of the following occurs?

Neurotransmitter is removed from postsynaptic receptors.

Anaxonic neurons

No axon; multiple dendrites

Which term refers to the gaps between segments of myelin along an axon?

Nodes of Ranvier

Multipolar neurons

One axon; multiple dendrites

Bipolar neurons

One axon; one dendrite

GABA has an inhibitory effect on postsynaptic neurons because it does which of the following?

Opens chloride channels

Which scientist conclusively demonstrated that neurons communicate by releasing chemical messages?

Otto Loewi

What type of output will occur when a parallel after-discharge circuit is stimulated?

Output will last longer than the stimulus lasts.

Taken together, the sensory and motor subdivisions make up which of the following?

Peripheral nervous system

Synapses are not fixed for life. In response to experience, they can be modified to make transmission easier or harder. The ability of synapses to change is called synaptic _____ .

Plasticity

Which term is used to refer to a cell membrane across which there is a separation of electrical charge, so that one side is more positive and the other side is more negative?

Polarized

Neural integration is based on the combining together of which of the following?

Postsynaptic potentials

Memories lasting for a few hours, such as recalling an incident earlier in the day, may be due to which of the following?

Posttetanic potentiation

Which ion has the greatest influence on the resting membrane potential of most neurons?

Potassium

An electrical potential is a form of what type of energy?

Potential energy

Synapses in a certain pathway can be modified to allow signals to travel more easily across "trained" synapses. Which term refers to the process of making transmission easier?

Potentiation

The ability of a neuron to enhance the effect of another neuron is called what?

Presynaptic facilitation

Firing additional neurons as a stimulus becomes stronger is an example of which of the following?

Recruitment

Which term refers to the period of time after a nerve cell has responded to a stimulus in which it cannot be excited by a threshold stimulus?

Refractory period

After a nerve cell responds to a stimulus, the period of time when the cell can not respond again except to an unusually strong stimulus is called what?

Relative refractory period

Which type of axonal transport involves movement up the axon toward the soma?

Retrograde

Dynein

Retrograde transport

Immediate memory, which is the ability to hold something in mind for a few seconds, might be based on activity in which type of neural circuit?

Reverberating

In a which type of circuit will one input signal cause a prolonged and repetitive output because a neuron late in the circuit restimulates a neuron earlier in the circuit?

Reverberating

Which term is used to describe signal conduction along a myelinated axon?

Saltatory

Which neuroglial cell is found in the peripheral nervous system?

Satellite cell

Which type of glial cell aids in regeneration of damaged peripheral nerve fibers by forming a regeneration tube to help reestablish the former connection?

Schwann cells

Which two types of neuroglia are found only in the peripheral nervous system?

Schwann cells and satellite cells

The release of a neurotransmitter is an example of which physiological property exhibited by a neuron?

Secretion

Which type of neuron begins in most body organs and carries information toward the central nervous system?

Sensory neuron

Which type of memory allows you to remember things from up to a few hours ago?

Short-term

Which is true about a neuron with a large diameter, myelinated axon as compared to a neuron with a small diameter, unmyelinated axon?

Signal conduction will be faster

Excitatory postsynaptic potentials (EPSPs) are usually due to the entry of which type of ion?

Sodium

Why is sodium more concentrated in the ECF than in the ICF of most neurons?

Sodium is actively pumped out of the cell by transporter proteins.

The sensory and motor divisions of the peripheral nervous system are further split into which two subdivisions?

Somatic and visceral

______ summation results when EPSPs occurring at multiple synapses add up to threshold at the axon hillock.

Spatial

When EPSPs from several synapses add up to threshold at the axon hillock, this process is called what?

Spatial summation

Parkinson disease is due to the progressive degeneration of dopamine-releasing neurons in which brain area?

Substantia nigra

There are two ways in which EPSPs can add up to produce enough activity to make a postsynaptic cell fire. They are temporal and spatial _____ .

Summation

This picture illustrates a phenomenon that occurs in the trigger zone when multiple postsynaptic potentials combine their effects on a cell to produce a response. What is it called?

Summation

Which division inhibits digestion?

Sympathetic

Which term refers to the microscopic physical gap between the presynaptic and postsynaptic neurons at a chemical synapse?

Synaptic cleft

Which term refers to summation that results from a single synapse firing rapidly in sequence?

Temporal

When a single synapse generates EPSPs so quickly that each is generated before the previous one fades, what is this process called?

Temporal summation

What type of stimulation is caused by rapid, repetitive signals arriving at a synaptic knob, causing progressively larger quantities of calcium to accumulate and leading to synaptic facilitation?

Tetanic

A negative membrane potential indicates which of the following?

The inside of the membrane is negatively charged relative to the outside.

Which best describes an electrical current?

The movement of charged particles like ions

In order for a peripheral nerve fiber to regenerate it must have which of the following?

The soma and at least some neurilemma intact

Some neurotransmitters can have either excitatory or inhibitory effects depending on which of the following?

The type of receptors on the postsynaptic cell

Which statement is true concerning the distribution of voltage-gated ion channels along a myelinated axon?

They are much more numerous in the nodes of Ranvier.

Which of the following is true about action potentials?

They do not decrease with distance (nondecremental).

Which are true about action potentials?

They usually cannot be stopped once they have begun (irreversible).

In order for local potentials to trigger an action potential, the membrane must depolarize up to a level called which of the following?

Threshold

Why would the synapses of a memory trace undergo synaptic potentiation?

To allow easier signal transmission along pathway

What is the primary function of the myelin sheath?

To increase the speed of signal conduction in the axon

What is the role of neural pools in the CNS?

To process information

True or false: Action potentials occur only where there are voltage-gated ion channels.

True

True or false: As long as there is an electrical potential across a cell membrane, we say that the membrane is polarized.

True

True or false: Unmyelinated nerve fibers (axons) in the PNS are enveloped in Schwann cells.

True

Which type of neuron has one single process that branches like a T into a peripheral fiber and a central fiber?

Unipolar

Which lists the structural categories of neurons?

Unipolar, bipolar, anaxonic, and multipolar

How long can long-term memory last?

Up to a lifetime

Enkephalins

Various areas of the brain, spinal cord; act as analgesics by inhibiting substance P, secretion increases during labor.

Together, the sympathetic and parasympathetic nervous systems make up the entirety of which division of the nervous system?

Visceral motor

Which term is another name for the autonomic nervous system?

Visceral motor division

This picture shows an excitatory postsynaptic potential (EPSP). When do EPSPs usually occur?

When sodium channels open

Looking up a new phone number and then dialing it from memory utilizes which type of memory?

Working memory

After a nerve cell responds to a stimulus, the period of time when the cell can not respond again, regardless of the strength of stimulus, is called the _____ refractory period.

absolute

Another term for sensory division is ______ division.

afferent

Neurons that have multiple dendrites but no axons, and which do not produce action potentials, are called ______ neurons. Multiple choice question. multipolar

anaxonic

Movement away from the neuron cell body toward an axon ending is called ______ transport.

anterograde

A neuron with one axon and one dendrite is structurally classified as a neuron.

bipolar

The brain and spinal cord are components of the ______ nervous system, while the nerves and ganglia are components of the ______ nervous system.

central, peripheral

The nervous system must interpret quantitative and qualitative information about its environment, thus it converts information to a meaningful pattern of action potentials. This process is called neural _____ .

coding

The processes that branch from the somas of most neurons are called ______.

dendrites

The type of circuit in which one input nerve fiber synapses with multiple postsynaptic neurons is a _____ circuit.

diverging

The motor division is also called the ______ division.

efferent

Two organ systems are dedicated to internal coordination, communication between the other systems, and maintaining the overall homeostasis of the body. They are _____ the system, which communicates by means of hormones, and the _____ system which sends quick electrical and chemical messages from cell to cell.

endocrine, nervous

Choose the name of the thin layer of fibrous connective tissue found around myelin in nerve fibers of the peripheral nervous system.

endoneurium

The glial cells that line cavities of the brain and spinal cord and secrete and circulate cerebrospinal fluid are ______.

ependymal cells

The plural form of ganglion is ______.

ganglia

A shift in membrane voltage to a value that is more negative than the resting membrane potential is called ______.

hyperpolarization

Neuroglial cells that act as macrophages within the CNS are ______.

microglia

The picture shows the most common structural type of neuron. It contains one axon and multiple dendrites, and it is classified as a(n) ______ neuron.

multipolar

The ______ (the cell body of a neuron) gives rise to branch-like processes called ______, which are the primary sites for receiving signals from other neurons.

neurosoma, dendrites

In the CNS, myelin is produced by glial cells called _____ .

oligodendrocytes

At a synapse, the neuron that responds to the neurotransmitter is the ______ neuron.

postsynaptic

In a chemical synapse, synaptic vesicles full of neurotransmitter are docked at release sites on the membrane of the presynaptic neuron, while neurotransmitter receptors are found on the membrane of the _____ neuron.

postsynaptic

At a synapse, the neuron that releases neurotransmitter is the ______ neuron.

presynaptic

The refractory period in which it is possible to trigger a new action potential, but only with an unusually strong stimulus is the ______ refractory period.

relative

At rest, K+ diffuses out of the cell through leak channels, resulting in a slight local accumulation of positive charge on the outside of the membrane (due to excess K+) and a slight local accumulation of negative charge on the inside of the membrane (due to decreased K+). This describes the basis of the _____ membrane potential.

resting

Propagation of an action potential down a myelinated axon in which the action potential appears to "jump" from node to node is called _____ conduction.

saltatory

______ cells are glial cells in the peripheral nervous system that surround somas of neurons in the ganglia, provide electrical insulation, and regulate the chemical environment of neurons.

satellite

Afferent neurons are ______ neurons.

sensory

The motor division of the PNS is further subdivided into the ______ motor division that carries signals to the skeletal muscles and the ______ motor division (also known as the autonomic nervous system), which carries signals to glands, cardiac muscle, and smooth muscle.

somatic, visceral

The sensory division of the PNS is further subdivided into the ______ sensory division, which carries signals from receptors in the skin, muscles, bones, and joints, and the ______ sensory division, which carries signals from organs of the thoracic and abdominal cavities.

somatic, visceral

What are the two divisions of the visceral motor division?

sympathetic and parasympathetic

The autonomic nervous system is subdivided into the ______ division which tends to arouse the body for action and the ______ division which tends to have a calming effect.

sympathetic, parasympathetic

At its distal end, an axon has an extensive complex of fine branches called a(n) ______.

terminal arborization

The region indicated by the circle is the ______. It plays an important role in initiating a nerve signal. It is formed by the axon hillock and the initial segment.

trigger zone

The region that plays an important role in initiating a nerve signal and is formed by the axon hillock and the initial segment is the ______.

trigger zone

Neurons with a single process extending from the soma, such as the neurons that carry sensory signals to the spinal cord, are classified structurally as ______ neurons.

unipolar

An axon lacking a myelin sheath is said to be ______.

unmyelinated