Chapter 12: nervous tissue - anatomy

Choose all of the following statements that are true about signal conduction along unmyelinated fibers.

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

Long-term potentiation may be involved in long-term memory. Choose all of the following that are molecular changes that occur in long-term potentiation.

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

Choose all statements that are true about Schwann cells?

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

Choose all statements that 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.

Choose all that are characteristics of neural pools.

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

Choose all that are the principal types of neural circuits.

- parallel after-discharge circuit - reverberating circuit - converging circuit - diverging circuit

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

-55

Select all that are categories of neurotransmitters based on chemical composition.

-Acetylcholine -Neuropeptides -Monoamines -Amino acids

Choose all that would cause postsynaptic stimulation to end.

-cessation of signals in the presynaptic nerve fiber -reuptake of neurotransmitter into the presynaptic knob -diffusion of neurotransmitter from the synaptic cleft into the extracellular fluid -enzymatic degradation of neurotransmitter in the synaptic cleft

Order of Events:

1. Local Potential Depolarizes Membrane 2. Threshold is Reached. 3. Depolarization Spike 4. Repolarization 5. Hyperpolarization

Which best describes an electrical potential?

A form of potential energy that can produce current

In posttetanic potentiation, which of the following is released?

A large burst of neurotransmitter

A local potential is what type of change in voltage?

A short-range change only

Which best describes signal conduction in unmyelinated axons?

A wave of depolarization opens more voltage-gated channels immediately distal to the action potential.

Aspartate is what type of neurotransmitter?

Amino acid

Branch the originates from an axon

Axon collateral

resting membrane potential =

Both types of voltage-gated channels are closed.

Where are unmyelinated axons found?

CNS & PNS

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.

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

Chloride

A pathway of neurons in a neural pool is called a neural ____.

Circuit

A pathway of neurons in a neural pool is called a neural _____.

Circuit

Input from many neurons going to fewer and fewer neurons is an example of a(n) ________ circuit.

Converging

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

Dendrites

Choose all the factors that influence the speed of nerve signal conduction.

Diameter of axon Presence of myelin

Which of the following is required for nerve fiber regeneration?

Endoneurium

Which cells protect the neurons and help them function?

Ependymal

All neurotransmitters have an excitatory effect.

False

Damaged nerve fibers in the CNS regenerate very fast whereas damaged nerve fibers in the PNS never regenerate.

False

NMDA receptors bind which neurotransmitter?

Glutamate

Choose all the neurotransmitters that are classified as amino acids.

Glutamate and GABA

The memory that is the ability to hold something in mind for just a few seconds is called ________ memory.

Immediate

The ability of your neurons to process information, store and recall information, and to make decisions is called neural ______ .

Integration

Which of the following would have the fasted conduction speed?

Large myelinated axob

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

Lipids

The type of memory that lasts up to a lifetime is ______-term memory.

Long

When GABA is used, more chloride channels open which makes the inside of the cell what?

More negative

Which action occurs first and leads to the repolarization of the cell membrane?

Movement of potassium to the outside of the cell membrane.

The structure that consists of spiral layers of insulation around an axon is called a(n) ____ sheath.

Myelin

Name the outer covering of the neuron indicated by the arrow labeled A.

Myelin Sheath

Which cells protect the neurons and help them function?

Neuroglia

A large collection of interneurons that function in one big ensemble is called a(n) _____ pool.

Neuronal

Choose all that are names for the cell body of a neuron.

Neurosoma and Soma

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.

Molecules that are synthesized by a neuron and are released when a nerve signal reaches an axon terminal are called ____.

Neurotransmitters

Which is the simplest neuromodulator?

Nitric oxide

Choose all that are usually found inside the cell body (or soma) of a mature neuron.

Nucleus Mitochondria Rough endoplasmic reticulum

The neuron that responds to the presynaptic neuron is called the _____ neuron.

Postsynaptic

EPSPs and IPSPs are examples of what?

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

The plasma membrane is most permeable to which of the following ions?

Potassium / K

A voltage of about -70mV is an average _____ membrane potential of a typical neuron.

Resting

Identify the type of cell indicated by the arrow labeled A.

Schwann cell

Which type of glial cell produces the myelin sheath in the PNS?

Schwann 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

Afferent neurons are what type of neurons?

Sensory

Neural coding is called what then it occurs in sense organs?

Sensory coding

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

The process of adding up postsynaptic potentials and responding to their net effect is called what?

Summation

Which is true about synapses?

Synapses can be deleted or created in as little as 1 or 2 hours

Synaptic potentiation is a form of what?

Synaptic plasticity

The type of summation that occurs when a single synapse generates EPSPs so quickly that each is generated before the previous one fades out is called _____ summation.

Temporal

The rapid arrival of repetitive signals at a synapse is called ______ stimulation.

Tetanic

Which best describes an electrical current?

The movement of charged particles like ions

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

The type of receptors on the postsynaptic cell

Choose all that are characteristics of neuroglia.

They protect the neurons and help them function. They bind neurons together and provide a supportive scaffold.

The minimum amount of voltage needed to open voltage-gated channels on an axon is called what?

Threshold

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

To allow easier signal transmission along pathway

Unmyelinated nerve fibers (axons) in the PNS are enveloped in Schwann cells

True

Which lists the structural categories of neurons?

Unipolar, bipolar, anaxonic, and multipolar

Continuous conduction occurs in what type of axon?

Unmyelinated only

Repolarization begins:

Voltage-gated Na+ channels inactivate; voltage-gated K+ channels remain open longer.

depolarization begins =

Voltage-gated Na+ channels open; voltage-gated K+ channels open more slowly.

When do EPSPs usually occur?

When sodium channels open

The refractory period in which no stimulus of any strength will trigger a new action potential is the ______ refractory period.

absolute

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

acetylcholine

Choose all statements that are true about Schwann cells?

all of the above

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

amino acids

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

astrocytes, microglia, oligodendrocytes, ependymal cells

Plasma membrane of axon

axolemma

A mound located on one side of the soma from which the axon originates

axon hillock

In a synapse, where are synaptic vesicles located?

axon terminal

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

axon terminals

cytoplasm of axon

axoplasm

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

Which are the sites of learning and memory?

chemical synapses

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

cholinergic

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

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

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

current

Choose all that are types of long-term memory?

declarative and procedural

The processes of a neuron that usually receive signals from other neurons are called

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

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

diverging

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

diverging

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

ependymal cells

Which glial cell produces and helps circulate cerebrospinal fluid?

ependymal cells

Which neurotransmitter is a catecholamine?

epinephrine

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

gap junctions

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

The myelin sheath is a spiral layer of ______ around a nerve fiber.

insulation

Saltatory conduction means which of the following terms?

leaping

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

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

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

multipolar

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

neural circuit

This picture illustrates that when a stimulus strength (weight) and stretch increase at a sensory fiber, the firing frequency of the neurons increase. Which term refers to the conversion of stimulus information into a meaningful pattern of action potentials?

neural coding

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

neural integration

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

Which glial cell insulates nerve fibers from extracellular fluids and speeds up signal conduction in the brain?

oligodendrocyte

Which type of glial cell is indicated by the arrow labeled A?

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

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

postsynaptic potentials

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

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

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

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

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

What are the three functional classes of neurons?

sensory neurons, interneurons, motor neurons

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

short term

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

Which division inhibits digestion?

sympathetic

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

temporal

At its distal end, an axon has an extensive complex of fine branches called what?

terminal arborization

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

An axon lacking a myelin sheath is said to be what?

unmyelinated