Chapter 12

What division carries signals from the CNS to gland and muscle cells that carry out the body's responses? What are the cells and organs that respond called?

Motor (efferent) division; effectors

What are nodes of Ranvier?

Myelin sheath gaps between adjacent Schwann cells Sites where axon collaterals can emerge

A stimulus at the dendrite binds to receptors that open ____ gates in the membrane so that Na+ flows into the cell, neutralizing some of the negative charges.

Na+

Electrical currents in the body are created by the flow of ions such as ___+ and ___+ through gated channels.

Na; P

Which alter synaptic transmission by adjusting the sensitivity of postsynaptic neurons to neurotransmitters or by affecting the breakdown and/or removal of a neurotransmitter? Multiple choice question. Cyclic AMP Myelin sheaths Neuromodulators Calcium ions

Neuromodulators

Which alter synaptic transmission by adjusting the sensitivity of postsynaptic neurons to neurotransmitters or by affecting the breakdown and/or removal of a neurotransmitter? Multiple choice question. Myelin sheaths Neuromodulators Cyclic AMP Calcium ions

Neuromodulators

Sensory, association and motor are the three classes of what? Multiple choice question. Ganglia Neuroglia Neurons Neurotransmitters

Neurons

Select the four categories of neurotransmitters based on chemical composition. Multiple select question. Neuropeptides Sterols Glycoproteins Acetylcholine Amino acids Monoamines

Neuropeptides Acetylcholine Amino acids Monoamines

What is the control center known as?

Neurosoma

Cessation of a signal occurs when neurotransmitter stops being released and when neurotransmitter already present in the synaptic cleft is removed. The removal of neurotransmitter from the synaptic cleft is accomplished in three ways. What are these three ways?

Neurotransmitter degradation, Reuptake, diffusion

Stimulation of the postsynaptic neuron will end when nerve signals stop arriving at the presynaptic axon terminal or when which of the following occurs? Multiple choice question. Receptors on postsynaptic membrane are removed. Neurotransmitter is removed from postsynaptic receptors. All postsynaptic receptors have neurotransmitter bound to them.

Neurotransmitter is removed from postsynaptic receptors.

Neural integration is based on the combining together of which of the following? Multiple choice question. Postsynaptic potentials Neurotransmitters Action potentials Presynaptic potentials

Postsynaptic potentials

Which ion has the greatest influence on the resting membrane potential of most neurons? Multiple choice question. Calcium Potassium Sodium Chloride

Potassium

Which factors influence the speed of nerve signal conduction? Multiple select question. Type of neuron (multipolar vs. unipolar) Presence of myelin Size of soma Diameter of axon

Presence of myelin Diameter of axon

Nerve fibers of the PNS are vulnerable to trauma, but may regenerate if its ______ is intact and at least some neurilemma remains. Can you briefly describe this process?

Soma; Schwann cells produce cell adhesion molecules as well as nerve growth factors to attach the nerve back to its original placement

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? Multiple choice question. Propagation Reverberation Inhibition Summation

Summation

The structure of a chemical synapse includes the ________ ____, a part of the presynaptic neuron that contains synaptic vesicles.

Synaptic knob

What does the central nervous system (CNS) consist of?

The brain and spinal cord

Which statements are true regarding postsynaptic potentials?

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

Which statements characterize neurotransmitters? Multiple select question. They are found in dendrites of postsynaptic neurons. They stimulate the opening of voltage-regulated gates at the postsynaptic membrane. They bind to receptors and alter the physiology of the postsynaptic cell. They are released in response to stimulation. They are synthesized by presynaptic neurons.

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

Which are characteristics of neural pools? Multiple select question. They consist of sensory neurons that synapse directly onto motor neurons. They consist of complex patterns of interneurons. They may be concerned with a particular body function. They classify neurons based on shape.

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

The membrane potential is -______ mV in a "resting" neuron. The negative value means more negative charges are on the inside of the membrane than on the outside.

-70

Neurons fall into three functional classes based on the three major aspects of nervous system function. What are these three classes and what are they doing?

-sensory(afferent)neurons, specialized to detect stimuli such as heat, light pressure, chemicals and transmit information to the CNS -Interneurons, receive information and determine how the body responds -motor(efferent) neurons, send signals to muscles and glands

The nervous system carries out its coordinating task in three basic steps. What are these three basic steps?

1) It receives information about changes inside and outside of the body and transmits the messages to the Central Nervous System 2)The CNS processes the information and determines a response 3) The CNS issues commands to muscles or glands to carry out a response if needed

Two key issues in neurophysiology are:

1) how does a neuron generate an electrical signal? 2)How does it transmit a meaningful message to the next cell?

Four characteristics distinguish local potentials from action potentials. What are these four and what do they mean?

1) local potentials are graded, meaning they vary in magnitude 2) are decremental, meaning they get weaker the further away they get from point of origin 3) are reversible, can quickly return to RMP 4)can be either excitatory and inhibitory ,

For every 1 ATP consumed by the Na+-K+ pump, ___ Na+ are pumped out of the cell and ___ K+ are brought in.

3; 2

At equilibrium, K+ is ____ times as concentrated in the ICF as in the ECF.

40

The Na+-K+ pump accounts for about ____% of the ATP requirement of the nervous system and it works continually, which is why the nervous system consumes so much glucose and oxygen.

70%

What is a ganglion?

A cluster of nerve cell bodies in the PNS

Which best describes an electrical potential? Multiple choice question. A form of potential energy that can produce current The movement of charged particles like ions The opposition to the flow of electrical current across a membrane A positively or negatively charged atom or molecule

A form of potential energy that can produce current

What is a presynaptic neuron? What does it do? What is a postsynaptic neuron? What does it do?

A neuron that conducts signals to the synapse; A neuron that receives signals

What do Oligodendrocytes resemble? What is myelin sheath and what does it do?

An octopus; a fibrous sheet that wraps around axon cells helps transmit information

Which types of glial cells are found in the central nervous system? Multiple select question. Schwann cells Astrocytes Oligodendrocytes Satellite cells Microglia Ependymal cells

Astrocytes Oligodendrocytes Microglia Ependymal cells

A presynaptic neuron may form an ____________, axosomatic, or _____________ synapse.

Axodendritic; Axoaxonic

Which term refers to the passage of proteins, organelles and other materials along an axon? Multiple choice question. Secretion Axonal transport Active transport Synaptic signaling

Axonal transport

______ _________refers to the passage of proteins, organelles, and other materials along an axon, to and from the cell soma.

Axonal transport

Which are characteristics of neural pools? Multiple select question. They classify neurons based on shape. They consist of sensory neurons that synapse directly onto motor neurons. They may be concerned with a particular body function. They consist of complex patterns of interneurons.

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

Na+ is 12 times more concentrated in the _____ than in the _____.

ECF; ICF

What two organ systems are dedicated to maintaining internal coordination?

Endocrine and Nervous systems

List the fundamental physiological properties of neurons. Multiple choice question. Elasticity, conductivity, contractility Excitability, conductivity, secretion Excitability, irritability, highly mitotic Conductivity, contractility, excitability

Excitability, conductivity, secretion

In electrical synapses, electrical signals move quickly from cell to cell through which of the following? Multiple choice question. Voltage-gated ion channels Neurotransmitter receptors Na+-K+ pumps Gap junctions

Gap junctions

______ cells protect the neurons and help them function. Multiple choice question. Glial Efferent Afferent Multipolar

Glial

There are six types of neuroglia, each of which has a unique function; four types occur only in the CNS

In CNS: Oligodendrocytes, Ependymal, microglia, astrocytes ; in PNS Schwann and satellite cells

In a synapse, where are synaptic vesicles located? Multiple choice question. In the axon terminal In the synaptic cleft In the dendritic terminal

In the axon terminal

What is the role of neural pools in the CNS? Multiple choice question. To produce neurotransmitter To process information To speed up nerve conduction To generate action potentials

To process information

Action potentials occur only where there are voltage-gated ion channels. True false question. True False

True

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

True

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

True

Looking up a new phone number and then dialing it from memory utilizes which type of memory? Multiple choice question. Working memory Implicit memory Long-term memory

Working memory

What do Ependymal cells resemble? What do they produce?

a cuboidal lining; CSF

What does the cytoskeleton consist of? What are Nissl bodies?

a dense mesh of microtubles and neurofibrils ;bundles of actin filaments

The sympathetic division tends to arouse the body for action. What are some examples of this?

accelerating heartbeat and increasing respiratory airflow

The neuron produces an ______ _________. The voltage-gated Na+ do what? What are K+ gates doing at this time? What happens to the membrane?

action potential; further depolarizes the membrane

What does the peripheral nervous system (PNS) consist of? What is it composed of?

all the rest; it is composed of nerves and ganglia

An unmyelinated fiber has voltage-gated channels where?

along its entire length

Signal conduction occurs where?

along the surface of a fiber

What is anterograde transport? What is retrograde transport?

away from soma down the axon; up the axon toward the soma

Which fundamental physiological property of neurons allows them to send signals quickly over long distances? Multiple choice question. Conductivity Secretion Excitability Contractility

conductivity

The local potential must rise to the _________ (about -55 mV) to open the voltage-gated channels.

critical

In the PNS, a Schwann cell spirals repeatedly around a single nerve fiber, laying down up to 100 compact layers of its own membrane with almost no _________.

cytoplasm

What is the axoplasm and axolemma?

cytoplasm of the axon ; its membrane

Typically, a neuron's response begins at the _______, spreads through the soma, travels down the _____, and ends at the synaptic knobs.

dendrites; axon

The current arrives at the axon hillock and ____________ the membrane as a local potential.

depolarizes

Neurotransmitters have _______ _______ ; three examples of different modes of action are illustrated by an excitatory cholinergic synapse, an inhibitory GABA-ergic synapse, and an excitatory adrenergic synapse.

diverse actions

Many of the presynaptic neuron's vesicles are "______" at the membrane, while others farther away constitute a reserve pool.

docked

When an action potential occurs at the trigger zone, Na+ _______ the axon and the resulting ______________ excites voltage-gated channels immediately distal to the action potential.

enters; depolarization

Where are Schwann cells found (which division of the nervous system) and what do they do?

envelop the nerve fibers of the PNS; form myelin

The negative ICF attracts K+ back into the cell and eventually _________ is reached between concentration-driven diffusion and electrical attraction, resulting in no further net diffusion of K+.

equilibrium

Nerve cells, or neurons, have three fundamental physiological properties that enable them to communicate with other cells. What are these three properties?

excitability, conductivity and secretion

What are dendrites and what function do they serve?

extension of neurons that receive information

The resting membrane potential exists because electrolytes are unequally distributed between the _________________ and the ___________

extracellular fluid (ECF); intracellular fluid (ICF).

The somatic sensory division carries signals from where?

from receptors in the skin, muscles, bones, and joints

The visceral sensory division carries signals from where?

from the viscera of the abdominal and thoracic cavities

The visceral motor division carries signals where? What are visceral reflexes?

glands, cardiac and smooth muscles ; involuntary

The axon (nerve fiber) originates on a mound on the soma called the axon __________.

hillock

Action potentials follow an all-or-none law and are not graded; What does this mean?

if it the voltage does not reach the neuron threshold it doesn't fire at all

Where are Satellite cells found and what do they do?

in the somas of the ganglia; provide insulation around the soma

As the rising membrane potential passes 0 mV, Na+ channels are ____________ and begin closing. By the time they all close, the voltage peaks at about +35 mV.

inactivated

What is hyperpolarization (or afterpotential)? What is happening here to create this?

membrane potential is more negative than usual; potassium channels stay open longer than sodium channels

Production of the myelin sheath is called what? When does it begin and when is it complete?

myelination; 14th week of fetal development and completed into late adolescences

Many cytoplasmic anions cannot escape from the cell because of their size or charge, so that diffusion of K+ out of the cell down its concentration gradient leaves the ICF with a net _________ charge.

negatively

Local changes in membrane potential occur when a ______ is stimulated.

neuron

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. Multiple choice question. axons, dendrites dendrites, axons neurosoma, axons neurosoma, dendrites

neurosoma, dendrites

The postsynaptic neuron has no synaptic vesicles and cannot release neurotransmitters. The membrane does contain what?

neurotransmitter receptors and ligand-gated ion channels

The synapse contains synaptic vesicles full of what?

neurotransmitters

Do mature neurons divide?

no

What are unipolar neurons? Where are these found?

no axon ;the skin

What does the Neurosoma contain ?

nucleus

Neurons are outnumbered by as much as 10 to 1 by cells called _______, or glial cells. What is one of the main roles of these cells in regards to neurons?

nuerogila

Neurons vary in structure, and they are classified according to the ______ of processes extending from the soma.

number

What are multipolar neurons?

one axon and multiple dendrites

What are bipolar neurons? Can you give some examples?

one axon and one dendrite; olfactory cells

By the time the voltage peaks, the slow K+ gates are fully ______, and K+ now ______ the cell, which acts to __________ the membrane.

open; exit ;repolarize

What is the composition of myelin?

plasma membranes of glial cells; 80% lipid, 20% protein

As long as a battery has an electrical potential, it is _________

polarized.

What ions have the greatest influence on RMP and why?

potassium because it is more permeable than any other ion

At a synapse, the neuron that releases neurotransmitter is the ______ neuron. Multiple choice question. postsynaptic presynaptic

presynaptic

During an action potential and for a few milliseconds after, the neuron cannot be stimulated to fire again. This period is called the _________ _________

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. Multiple choice question. absolute relative

relative

The refractory period has two phases: What are these two periods and is a stimulus able to trigger a new action potential in either one?

relative refractory period and absolute refectory period; yes

What is saltatory conduction?

saltatory conduction is the "jumping" of an action potential between the unmyelinated nodes of ranvier

An axon is specialized for what?

sending information from the soma

Afferent neurons are ______ neurons. Multiple choice question. motor sensory

sensory

What two divisions is the PNS divided into?

sensory(afferent) and motor( efferent)

Large fibers have more surface area and conduct more _________ than small fibers.

signals

Slow unmyelinated fibers are sufficient for many processes. Fast myelinated fibers occur where speed is vital, such as in motor commands to ________ _________.

skeletal muscles

The somatic motor division carries signals where? What are somatic reflexes?

skeletal muscles; automatic reflexes

What are Microglia, and what do they do? Where would they become concentrated in?

small macrophages that develop white blood cells led monocytes; Through the brain

A node of Ranvier occurs every millimeter or less along the axon, however, with an abundance of ________-_______ channels.

sodium-ion

What are internodes?

spaces between nodes

What do Astrocytes look like? What are some of their functions?

stars; supportive framework for the nervous system in the CNS

An action potential does not travel along an axon, but rather, it __________ the production of a new action potential just ahead of it.

stimulates

The parasympathetic division tends to have a calming effect. What is an example of this?

stimulates digestion and slows heartbeat

The autonomic nervous system has two further divisions.

sympathetic and parasympathetic

How does it transmit a meaningful message to the next cell?

synaptic transmission

The nervous system has two major anatomical subdivisions:

the central nervous system and peripheral nervous system

What is an electrical potential? What is an electrical current?

the difference in the concertation of charged particles from one point and another; A flow of charged particles from one point to another

What is neurobiology?

the study of cells of the nervous system and the organization of these cells into functional circuits that process information and mediate behavior

Action potentials are nondecremental; What does this mean?

they do not get weaker with distance

What is the neurilemma, and what does it contain?

thickest most outer layer, contains nucleus and most of the cytoplasm

An action potential is a rapid ____________ shift in membrane voltage produced by voltage-gated ion channels in the plasma membrane.

up-and-down

At the distal end, an axon usually has a terminal arborization (an extensive complex of fine branches). Each branch ends in a synaptic _______ (terminal button) that forms a _________ (synapse) with the next cell.

vesicles; axon terminal

During hyperpolarization, Na+ diffusion into the cell and (in the CNS) the removal of extracellular K+ by ___________ gradually restore the RMP.

voltage

Incoming Na+ ions diffuse for a short distance and produce a _______ (local potential) that travels from the stimulus point toward the cell's ______ zone.

voltage; trigger

When do action potentials occur?

when the neuron is stimulated past threshold

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 _____

code

The net effect of K+ diffusion outward, Na+ diffusion inward, and the action of the Na+-K+ pump is the RMP of -____ mV.

3

The axon is cylindrical and relatively unbranched for most of its length, although it may give rise to axon ___________ along the way.

collaterals

What is the approximate ratio of glial cells to neurons? Multiple choice question. 10:1 1:10 1:50 25:1

10:1

An excitatory cholinergic synapse employs acetylcholine (ACh) as its neurotransmitter. What are the steps in transmission?

1)arrival of the signal to axon terminal to open up calcium voltage gates 2) calcium enters the cell causes exocytosis of the synaptic vesicles releasing Acetylcholine(ACh) 3)this process continues like a conveyer belt of dumping ACh 4)meanwhile ACh diffuses across the synaptic Cleft , allowing the sodium to enter the cell and potassim to leave the cell 5)sodium then deploarizes the cell, producing a local voltage shift, it then causes the postsynpaitic neuron to fire

Three factors collectively determine the RMP. What are these three factors?

1)diffusion of ion downs their concentration gradient 2)selective permeability of the membrane 3)electrical attraction of cations and anions

What is meant by depolarization?

A shift in the electrical potential across a plasma membrane to a value less negative than the resting membrane potential

Which best describes signal conduction in unmyelinated axons? Multiple choice question. A wave of depolarization opens more voltage-gated channels immediately distal to the action potential. A local potential is passively conducted down the entire length of the axon. The entire axon depolarizes at the same time. The signal is transmitted from one node of Ranvier to the next through saltatory conduction.

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

Which best describes signal conduction in unmyelinated axons? Multiple choice question. A wave of depolarization opens more voltage-gated channels immediately distal to the action potential. A local potential is passively conducted down the entire length of the axon. The signal is transmitted from one node of Ranvier to the next through saltatory conduction. The entire axon depolarizes at the same time.

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

Indicate which of the following statements are true about signal conduction along unmyelinated fibers. Multiple select question. The signal conduction in unmyelinated fibers is saltatory. A zone of depolarization excites voltage-gated channels immediately distal to the action potential. The red band in the diagram represents the relative refractory period. Unmyelinated fibers have voltage-gated channels along their entire length.

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

More than 100 confirmed or suspected neurotransmitters have been identified. Neurotransmitters fall into four major categories according to composition. ______________, in a class by itself, is formed from acetic acid and choline.

Acetylcholine

Question Mode Multiple Choice Question A cholinergic synapse uses which of the following as its neurotransmitter? Multiple choice question. Norepinephrine Acetylcholine Endorphin Serotonin

Acetylcholine

How does a neuron generate an electrical signal?

Change the charge on the resting membrane Na and K involved Gates are involved Generate a potential, whether it is local or action Concentration gradients - chemical and electrical

Which term refers to a synapse that releases acetylcholine from the presynaptic axon terminal? Multiple choice question. Adrenergic Serotonergic Cholinergic Electrical

Cholinergic

The Na+-K+ pump __________ compensates for the leakage of Na+ and K+ into and out of the cell.

Continually

Which are characteristics of local potentials? Multiple select question. Self-propagating Decremental All-or-none Graded

Decremental Graded

Which correctly describe axonal transport? Multiple select question. 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). It is a type of transport that occurs only in anaxonic neurons.

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 of the following contributes to the development of the resting membrane potential in neurons? Multiple choice question. Na+ and K+ have equal concentrations on both sides of the membrane. K+ is more concentrated in the ICF than in the ECF. Na+ is more concentrated in the ICF than in the ECF. K+ is more concentrated in the ECF than in the ICF.

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

The myelin sheath is composed mostly of which of the following? Multiple choice question. Lipids Proteins Carbohydrates Glycoproteins

Lipids

Which term refers to decremental changes in electrical potential along a dendrite or the soma? Multiple choice question. Resting potentials Local potentials Action potentials Synaptic potentials

Local potentials

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? Multiple choice question. Inhibitory period Refractory period Latent period Excitatory period

Refractory period

Which would cause postsynaptic stimulation to end? Multiple select question. Reuptake of neurotransmitter into the presynaptic knob Diffusion of neurotransmitter from the synaptic cleft into extracellular fluid Addition of receptors onto presynaptic membrane Cessation of signals in the presynaptic nerve fiber Enzymatic degradation of neurotransmitter in the synaptic cleft

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

Which neuroglial cell is found in the peripheral nervous system? Multiple choice question. Satellite cell Oligodendrocytes Ependymal cell Astrocyte

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? Multiple choice question. Satellite cells Ependymal cells Schwann cells Oligodendrocytes

Schwann cells

What division carries sensory signals from receptors to the CNS; this pathway informs the CNS of stimuli?

Sensory(afferent) division; stimuli within and around the body

Which is true about a neuron with a large diameter, myelinated axon as compared to a neuron with a small diameter, unmyelinated axon? Multiple choice question. More neurotransmitter will be released Less neurotransmitter will be released Signal conduction will be faster Signal conduction will be slower

Signal conduction will be faster

This chain reaction continues to the end of the ____

axon

Materials travel along microtubules of the _____________.

axonal

Why don't action potentials travel backwards?

because the membrane behind the nerve signal is still in its refractory period and cant be restimulated

Anaxonic neurons have multiple dendrites but no axon. They communicate through their dendrites and do not produce action potentials; Where are these found?

brain, retina and adrenal medulla

If a local potential spreads all the way to the trigger zone and is still strong enough, what can happen?

can become an action potential

In myelinated fibers, voltage-gated ion channels are scarce in the myelin-covered ___________.

internodal segments

What is a nerve?

is a bundle of nerve fibers (axons) wrapped in fibrous connective tissue.

Action potentials are irreversible; What does this mean?

it can not be stopped once it begins