Chapter 7 - GP

What is the part of the neuron that contains the nucleus and is responsible for the production of most of the cell's macromolecules?
Axon hillock
Cell body
Synaptic terminal
Dendrite

Cell body

Which of the following cell types are neuroglial cells located within the peripheral nervous system?
Oligodendrocytes
Astrocytes
Satellite cells
Schwann cells

Satellite cells and Schwann cells

What are the gaps in the myelin sheath?

Nodes of Ranvier

The blood-brain barrier is a feature of the \______.

brain capillaries

The \______ \______ is the enlarged portion of the neuron that contain the nucleus

cell body

The resting membrane potential is \______.
- the maximum voltage that a cell can achieve during stimulation
- the zero voltage that cells return to after excitation
- the voltage which all cells maintain between inside and outside

the voltage which all cells maintain between inside and outside

During the generation of an action potential, the neuron goes from the resting potential of -70mV to a high of \______ during the maximum point of sodium ion entry.

+30 mV

An action potential begins as \______.
a repolarization from resting potential
an increase in charge sufficient to achieve threshold
a hyperpolarization of resting potential

an increase in charge sufficient to achieve threshold

A synapse is \______.
the connection between a neuron and a second cell
the portion of a nerve that conducts an action potential
a receptor on the postsynaptic membrane

the connection between a neuron and a second cell

\______ junctions are water filled channels of connexin proteins through which ions can pass from one cell to another.

Gap

\__________________ conduction occurs within myelinated axons.

Saltatory

What is the functional connection between a neuron and an effector cell called?

Synapse

Cells that are electrically coupled and joined together share \______.

gap junctions

Saltatory conduction proceeds between \______.

Nodes of Ranvier

What enzyme is responsible for the inactivation of acetylcholine at the synaptic cleft?

Acetylcholinesterase

What are monoamines?
Secondary messengers
Regulatory molecules derived from amino acids
Neurotrophins
Neurotransmitters derived from acetylcholine

Regulatory molecules derived from amino acids

What is another name for an EPSP (excitatory postsynaptic potential) that is generated at the neuromuscular junction?

End plate potential

What is a neuron classified as if it uses acetylcholine as its neurotransmitter?

Cholinergic

Regulatory molecules derived from amino acids are called \_____________.

monoamines

What gaseous neurotransmitter is produced from L-arginine by nitric oxide synthetase?

NO

\______________________ neurotransmitters, such as endocannabinoids, are released from a postsynaptic neuron (sometimes from the dendrites of that neuron) and diffuse back to effect the presynaptic neuron.

Retrograde

\________________ receptors designated P1 for adenosine binding and P2 for ATP binding are found in neurons and glial cells.

Purinergic

When a neurotransmitter is released from the postsynaptic cell and diffuses backward to effect the axons of the presynaptic cell, the neurotransmitter is classified as a(n) \____________ neurotransmitter.

retrograde

\_______________ occurs when a number of axons synapse on a single neuron.

Convergence

\____________________ neurotransmitters, such as endocannabinoids, are released from a postsynaptic neuron (sometimes from the dendrites of that neuron) and diffuse back to effect the presynaptic neuron.

Retrograde

The ability of synapses to change in response to activity is called \__________ \________________.

synaptic plasticity

When a presynaptic neuron is experimentally stimulated at a high frequency, the excitability of the synapse is enhanced over time. This change represents the concept of: \___________ \_____________.

synaptic plasticity

When neurotransmitters such as GABA and glycine hyperpolarize the postsynaptic membrane of a neuron, this neuron is exhibiting \____________

long term potentiation

Postsynaptic inhibition:
- occurs when neurotransmitters like GABA hyperpolarize the neuron
- occurs when a cell's membrane potential becomes more positive and closer to threshold
- is caused by IPSPs or inhibitory postsynaptic potentials
- is caused by a decrease in the number of EPSPs that are released by the presynaptic cell

occurs when neurotransmitters like GABA hyperpolarize the neuron

is caused by IPSPs or inhibitory postsynaptic potentials

1. The arrival of the action potential at the presynaptic terminal causes \________.

-voltage-gated sodium channels to open
- acetylcholine to be directly released
- potassium leak channels to close
- calcium to enter the presynaptic terminal through voltage-gated calcium channels

calcium to enter the presynaptic terminal through voltage-gated calcium channels Correct

2. The increase in calcium ion concentration causes \________.
- voltage-gated potassium channels to open
- release of acetylcholine from the synaptic vesicles into the synaptic cleft
- a new action potential to be created that jumps across the synaptic cleft
- voltage-gated sodium channels to open

release of acetylcholine from the synaptic vesicles into the synaptic cleft

3. Acetylcholine diffuses across the synaptic
- binds to voltage-gated sodium channels
- directly initiates a new action potential on the postsynaptic membrane
- binds to ACh receptors that open ligand-gated sodium channels Correct
- causes potassium leak channels to close

binds to ACh receptors that open ligand-gated sodium channels

8. An action potential arriving at the presynaptic terminal causes \__________.
acetylcholine to diffuse into the cell
sodium ions to diffuse out of the cell
ligand-gated sodium channels to open
calcium ions to diffuse into the cell
sodium ions to diffuse into the cell

calcium ions to diffuse into the cell

10. What is the effect of the neurotransmitter at the neuromuscular junction?
- It causes ligand gated calcium channels in the muscle fiber to increase their permeability to calcium, which depolarizes the postsynaptic membrane.
- It causes ligand gated sodium channels in the muscle fiber to increase their permeability to sodium, which depolarizes the postsynaptic membrane. Correct
- It depolarizes the presynaptic membrane by increasing the permeability of sodium ions.
- It increases the sodium ion permeability of the presynaptic membrane.
- It increases the calcium ion permeability of the presynaptic membrane.

It causes ligand gated sodium channels in the muscle fiber to increase their permeability to sodium, which depolarizes the postsynaptic membrane.

What is the nigrostriatal tract?

- Neural tracts involved with mood and emotion
- Neural tracts that release dopamine and are involved in motor control
- Neural tracts that release dopamine
- Neural tracts that release serotonin

Neural tracts that release dopamine and are involved in motor control

2. What amino acid is a precursor of dopamine?

Tyrosine

4. Where is dopamine needed to relieve the symptoms of Parkinson's disease?
Red nucleus
Skeletal muscles
Substantia nigra
Basal nuclei

Basal nuclei

An action potential arriving at the presynaptic terminal causes \__________.
- voltage-gated sodium ion channels to open, and sodium ions to diffuse into the cell
- voltage-gated sodium ion channels to open, and sodium ions to diffuse out of the cell
- voltage-gated calcium ion channels to open, and calcium ions to diffuse into the cell
- acetylcholine to diffuse into the cell
- ligand-gated sodium channels to open, and sodium ions to diffuse out of the cell

voltage-gated calcium ion channels to open, and calcium ions to diffuse into the cell

Acetylcholine has which effect on the postsynaptic neuron?

- Ligand-gated calcium ion channels open and calcium diffuses inward.
- Ligand-gated sodium ion channels open and sodium diffuses inward.
- Terminal vessels migrate to the plasma membrane.
- Voltage-gated calcium ion channels open and calcium diffuses inward.
- Voltage-gated sodium ion channels open and sodium diffuses inward.

Ligand-gated sodium ion channels open and sodium diffuses inward.

Which of the following occurs when an action potential arrives at the presynaptic terminal?
- Synaptic vessels fuse with the plasma membrane and release acetylcholine.
- Acetylcholine is actively transported from the presynaptic neuron.
- Acetylcholine is actively transported to the postsynaptic neuron.
- Ligand-gated sodium channels open.
- Sodium ions diffuse into the cell.

Synaptic vessels fuse with the plasma membrane and release acetylcholine.

Depolarization occurs because \__________.
- more K+ diffuses into the cell than Na+ diffuses out of it
- more K+ diffuses out of the cell than Na+ diffuses into it
- more Na+ diffuses into the cell than K+ diffuses out of it
- more Na+ diffuses out of the cell than K+ diffuses into it
both Na+ and K+ diffuse into the cell

more Na+ diffuses into the cell than K+ diffuses out of it

Depolarization occurs because \__________.
- potassium ions continue to diffuse out of the cell after the inactivation gates of the voltage-gated sodium ion channels begin to close
- the extra efflux of potassium ions causes the membrane potential to become slightly more positive than the resting value
- the increased potassium ion permeability lasts slightly longer than the time required to bring the membrane potential back to its resting level
- sodium ions diffusing into the cell through ligand-gated channels is greater than potassium ions diffuse out of it
- the inactivation gates of the voltage-gated sodium ion channels begin to open and the diffusion of sodium ions decreases

sodium ions diffusing into the cell through ligand-gated channels is greater than potassium ions diffuse out of it

Repolarization occurs because \__________.
- potassium ions continue to diffuse out of the cell after the inactivation gates of the voltage-gated sodium ion channels begin to close
- the extra efflux of potassium ions causes the membrane potential to become slightly more positive than the resting value
- the increased potassium ion permeability lasts slightly longer than the time required to bring the membrane potential back to its resting level
- more sodium ions diffuse into the cell than potassium ions diffuse out of it
- the inactivation gates of the voltage-gated sodium ion channels begin to open and the diffusion of sodium ions decreases

potassium ions continue to diffuse out of the cell after the inactivation gates of the voltage-gated sodium ion channels begin to close

Hyperpolarization, or after potential occurs because \__________.
- potassium ions continue to diffuse out of the cell after the inactivation gates of the voltage-gated sodium ion channels begin to close
- the extra efflux of potassium ions causes the membrane potential to become slightly more positive than the resting value
- the increased potassium ion permeability lasts slightly longer than the time required to bring the membrane potential back to its resting level
- more sodium ions diffuse into the cell than potassium ions diffuse out of it
- the inactivation gates of the voltage-gated sodium ion channels begin to open and the diffusion of sodium ions decreases

the increased potassium ion permeability lasts slightly longer than the time required to bring the membrane potential back to its resting level

An action potential \__________.
- causes the neuron cell membrane to become unable to alter its charge
- causes the outside of the neuron cell membrane to become positively charged in reference to the inside
- causes the inside of the neuron cell membrane to become positively charged in reference to the outside
- causes the inside of the neuron cell membrane to become negatively charged in reference to the outside
- causes the inside of the neuron cell membrane to become neutrally charged in reference to the outside

causes the inside of the neuron cell membrane to become positively charged in reference to the outside

An action potential generates local currents that tend to \__________ the membrane immediately adjacent to the action potential.

depolarize

The absolute refractory period causes action potential propagation to \___________.

occur in one direction

1. When voltage-gated sodium channels are open, sodium flows \_____________ the neuron making the inside of the cell more \_______________.

into; positive
into; negative
out of; positive
out of; negative

into; positive

2. The following information best describes the \_____________ phase of an action potential.
A membrane potential reading of +10 mV
Inactivated voltage-gated sodium channels
Open voltage-gated potassium channels

repolarization
depolarization
resting
hyperpolarization

repolarization

1. Normally, sodium and potassium leakage channels differ because \___________________.

- sodium leakage channels are voltagegated, but potassium leakage channels are ligandgated
- sodium ions diffuse through leakage channels into the cell, but potassium ions diffuse through leakage channels out of the cell
- sodium leakage channels require ATP to transport ions, but potassium leakage channels do not
- sodium leakage channels always remain open, but potassium leakage channels must be specifically activated to open

sodium ions diffuse through leakage channels into the cell, but potassium ions diffuse through leakage channels out of the cell

2. A resting membrane potential of -70 mV indicates that the \________________.

- positive ions outnumber the negative ions within the cytosol
- charges lining the inside of the plasma membrane are negative compared to the charges lining the outside
- negative ions will always move into a cell
- negative ions are only present within the cytosol and are lacking in the extracellular fluid

charges lining the inside of the plasma membrane are negative compared to the charges lining the outside

1. At the synaptic terminal, voltage-gated \______________ channels open, thereby stimulating the synaptic vesicles to release their neurotransmitters by exocytosis.

calcium

2. Graded potentials result from the opening of \________________ channels.

ligand-gated

2. An inhibitory postsynaptic potential results from the opening of \____________________.
chloride and/or sodium channels
sodium and/or potassium channels
potassium and/or chloride channels

potassium and/or chloride channels

2. Indicate the summative effect that brings the initial segment closest to threshold.

- Two IPSPs in proximity to each other
- Two EPSPs in proximity to each other
- Two EPSPs located a large distance apart
- Two IPSPs located a large distance apart
- One IPSP and one EPSP in proximity to each other

Two EPSPs in proximity to each other

Nervous system is divided into what two systems and what do they encompass?

What are the two types of cells that are composed of tissue?

Central Nervous System (CNS): brain and spinal cord and Peripheral Nervous System (PNS)

Neurons that conduct impulses but generally cannot divide and neuroglia that support the neurons and cannot conduct impulses, but can divide

Neurons are \________, meaning most cannot divide, but can repair

amitotic

Cell body contains a nucleus, Nissi bodies, and other organelles; cluster in groups called \______ in the CNS and \_______ in the PNS

Dendrites receive impulses and conducts a graded response towards the \_____ \_____

Axon: conducts actions potentials \______ from the cell body

nuclei; ganglia

cell body

away

Axons
- Are connected to the cell body by the axon hillock where action potential are generated at the \________ segment of the axon
- Can form many branches called \_______ \_______________
- Coveted in myelin with open spots called \_________ \__ \__________

initial

axon collaterals

Nodes of Ranvier

What is axonal transport?

What does the fast component and slow components move?

An active process needed to move organelles and proteins from the cell body to axon terminals

Fast: membranous vesicles
Slow: microfilaments, microtubules, and proteins

Axonal Transport
Anterograde transport: from cell body to dendrites and axon; uses \_________ molecular motors; carriers neurotransmitters and ions

Retrograde transport: from dendrites and axon to the cell body; uses \________ molecular motors with its activator dynactin; carries lysosomes, autophagosomes, endosomes and other molecules; also carriers certain viruses and tetanus toxin

kinesin

dynein

Classification of Neurons and Nerves
- based on direction impulses are conducted

Sensory neurons: conduct impulses from sensory receptors to the CNS (\_________)

Motor neurons: conduct impulses from the CNS to target organs (muscles or glands; \__________)

Association/interneurons: located completely within the \___ and integrate functions of the nervous system

afferent

efferent

CNS

90% are interneurons

Motor Neurons
What are the two types of motor neurons?

What are each responsible for?

Somatic motor neurons and autonomic motor neurons

Somatic: responsible for reflexes and voluntary control of skeletal muscles

Autonomic: innervate involuntary targets such as smooth muscle, cardiac muscle, and glands
(sympathetic and parasympathetic)

Structural Classification of Neurons
Pseudounipolar: \______ short process that branches like a T to form 2 longer processes
Bipolar: \_____ processes, one on either end; found in retina of eye
Multipolar: several \______________ and one \____; most common; motor neurons

single
two
dendrites; axon

Nerves are bundles of axons located outside the \___; most are composed of both sensory and motor neurons and are called \_________ nerves

Some of the cranial nerves have sensory fibers only

A bundle of axons in the CNS is called a \_______.

CNS; mixed
tract

A bundle of cell bodies in the PNS is a \____________.
A bundle of cell bodies in the CNS is a \_____________.

ganglion
nucleus

\__________________ are cells that are non-conducting but support neurons
What are the two types that are found in the PNS?

Neuroglia
Schwann and satellite cells

PNS Neuroglia
Schwann cell form \___________ \___________ around peripheral axons

Satellite cells support \_______ \_________ within the ganglia of the PNS

myelin sheaths
cell bodies

CNS Neuroglia
Four types are found in the CNS:
\______________________: form myelin sheaths around the axons of CNS neurons
Microglia: migrate around CNS tissue and \_________________ foreign and degenerated material
Astrocyte: regulate the \__________ \______________ of the neurons
Ependymal cells: line the ventricles central canal of the spinal cord and secrete \_____________________ \_________

Oligodendrocytes
phagocytize
external environment
cerebrospinal fluid

What was produced in the embryonic yolk sac and migrated to the developing neural tube?

Microglia

Microglia has a small cell body with many fine processes; maintain healthy neuronal \__________ function

Infection or trauma can lead to microglial activation in which they become \___________, mobile cells

synaptic
phagocytotic

Microglia
Activated microglia sense ATP released from \___________ cells and migrate toward them

Proliferate by cell division

Kills endogenous pathogens, removes damaged dendrites, \_______ and other debris in the CNS

May shape neural \_______ by pruning axons to eliminate inappropriate synaptic connections

damaged
myelin
circuits

Myelin sheath in the PNS
All axons in the PNS are surrounded by a sheath of Schwann cells called the \_______________ (cytoplasm and organelles of the Schwann cell), or sheath of Schwann

These cells wrap around the axon to form the myelin sheath (wraps of the cell membrane of the Schwann cell) in the \____

Gaps between Schwann cells, called \_________ \___ \__________, are left open

neurilemma
PNS
nodes of Ranvier

Myelin sheath in the PNS
Small axons (2 micrometers in diameter) are usually \_________________.

Even unmyelinated axons in the PNS have a \_____________ but lack the multiple wrappings of the Schwann cell plasma membrane

Myelinated axons conduct impulses more \________.

unmyelinated
neurilemma
rapidly

Myelin sheath in the CNS
Myelin sheath is produced by \____________________________.

One oligodendrocytes sends extensions to several axons and each wraps around a section of an axon

Produces the myelin sheath but not a \_______________ (no cytoplasm or organelles)

oligodendrocytes
neurilemma

Myelin sheath in the CNS
Myelin gives these tissues (axons) - \_______ matter
\_______ matter is cell bodies and dendrites which lack myelin sheaths

white
gray

Demyelinating diseases are those in which the \________ \_________ are specifically attacked

Guillain-Barre syndrome: the T cells of the immune system \_______ the myelin sheaths of the PNS. This produces rapid onset of symptoms that include muscle weakness

Multiple sclerosis (MS): produced by an \_________________ attack by T lymphocytes causing lymphocytes and monocyte-derived macrophages to enter the brain and target the myelin sheaths causing demyelination

myelin sheaths
attack
autoimmune

When an axon in the PNS is cut, the severed part degenerates, and a \_______________ tube is formed by Schwann cells
1) Growth factors are leased that stimulate growth of axon sprouts within the tube
2) New axon eventually connects to the \__________________ axon or the effector
3) Schwann cells in the PNS also produce proteins that \_________ axon regeneration, but are removed by phagocytosis

regeneration
undamaged
inhibit

Can CNS axons able to regenerate?
1) Death receptors form that promote \_____________ of oligodendrocytes
2) Inhibitory proteins in the \_________ sheath prevents regeneration
3) Glial scars from astrocytes form that may aid regeneration when \_________________ growth factors are present

No, they are not able to
apoptosis
myelin
neurotrophic

CNS Regeneration
Injury in the CNS stimulates growth of axon collaterals, but \__________ axons have a much more limited ability to regenerate than peripheral axons

Proteins called \_______, produced predominantly by oligodendrocytes, inhibit axon regeneration in the CNS

central
Nogo (not good)

\_________________ promote neuronal growth in the fetal brain which includes nerve growth factor (NGF), brain-derived neurotrophic factor (BDNF), glial-derived neurotrophic factor (GDNF), and neurotrophin-3, neurotrophin-4/5

In adults, neurotrophins aid in the maintenance of sympathetic \___________ and the regeneration of sensory neurons

Neurotrophins
ganglia

\____________ are the most abundant glial cell

Processes with end-feet associate with blood capillaries and axon terminals; actually cover the \___________ surface of the capillaries

Have end-feet called terminal \___________ adjacent to synapses between neurons

Influences interactions between neurons and between neurons and blood

Astrocytes
entire
boutons

Astrocyte Functions
Take up \__ from the extracellular environment to maintain ionic environment for neurons
Take up \__________ (major excitatory NT) released from CNS axon terminals and produce glutamine. Chemicals are recycled. Inhibitory neurons convert glutamine to GABA, the major inhibitory NT
End-feet around capillaries take up \_______ from blood and convert to lactic acid for use by neuron to make ATP

K+
glutamate
glucose

Astrocyte Functions
Can store \___________ and produce lactate for neurons to use
Needed for the formation of synapses in the CNS
Regulate \__________________ in the hippocampus and subventricular zone of the adult brain
Create glial-derived neutrophobic factor (GDNF) for survival of spinal cord neurons and dopamine-releasing neurons

glycogen
neurogenesis

Astrocyte Functions
Form the \________-\________ barrier
Neurons communicate with astrocytes, shown in the \__________ to aid in coordinating motor activity
Release transmitter molecules (gliotransmitters) that can stimulate or inhibit neurons by responding to Ca2+ includes glutamate, ATP, adenosine, D-serine

blood-brain
cerebellum

Astrocytes and Neural Activity
Although astrocytes do not produce \________ \__________, they are excited by changes in \________________ Ca2+ concentration
When some neurons are active, they release ATP, which increases the Ca2+ of adjacent astrocytes; creates a Ca2+ \______
A rise in Ca2+ can also cause the astrocytes release \_________________ E2 from the end-feet on a blood capillary, increasing blood flow

action potentials; intracellular
wave
prostaglandin

Blood-brain barrier
Capillaries in the brain do not have pores between adjacent cells but are joined by \_______ junctions
Substances can only be moved by very \________ processes of diffusion through endothelial cells, ion channels, transport proteins (GLUT1 for glucose), and active transport

tight
selective

Blood-brain barrier
Movement is \___________________, not paracellular
Astrocytes influence the production of ion channels, carrier proteins, and enzymes that can destroy toxic substances by secreting \______-\_______ neutrotrophic factor
\_____________ - cells that surround the endothelium of CNS capillaries that produce transporters that provided two-way communication between endothelial cells and astrocytes

transcellular
glial-derived
Pericytes (who astrocytes talk to)

Blood-brain barrier
Creates problems with treatment of brain cancers, diseases, and infections because many drugs can not \___________ the blood-brain barrier

penetrate

Neurons and \_______ cells can change their membrane potentials

Called excitability or irritability

Caused by changes in the \__________ to certain ions

Ions will follow their electrochemical gradient which is a combination of concentration gradient and attraction to opposite charges

Flow of ions are called ion \_________ which occur in limited areas where ion channels are located

muscle
permeability
currents

When the membrane potential inside the cell increases (becomes more positive), this is called \________________ which usually occurs when positive ions enter the cell (usually Na+)

A return to resting potential is called \_____________________.

depolarization
repolarization

When the membrane potential inside the cell decreases (becomes more negative), this is called \_______________________ which occurs when positive ions leave the cell (usually K+) or negative ions (Cl-) enter the cell

Depolarization of the cell is \________________.

Hyperpolarization is \__________________.

hyperpolarization

excitatory

inhibitory

What are the two types of channels of K+?

Na+ has only \________-\_______ channels that are closed at rest through fast flickering occurs; the membrane is less permeable to Na+ at rest

1. Not gated (always open); sometimes called K+ leakage channels
2. Voltage-gated K+ channels; open when a particular membrane potential is reached; closed at resting potentia

voltage-gated

Na+ channels open if the membrane potential depolarizes to \________mV which is called the \_____________.
Sodium rushes in and these channels are deactivated at \_________mV
It is called a \__________ feedback loop which causes a rapid reversal of the membrane potential

-55
threshold
+30
positive

At +30mV, Na+ channels close, and K+ channels open
Results in \________________ of membrane potential which is called a \__________ feedback loop

repolarization
negative

After-hyperpolarization
Repolarization actually \____________ resting potential and gets down to -85mV
It does not reach \______________ equilibrium potential because voltage-fated K+ channels are inactivated as the membrane potential fails

overshoots
potassium

All-or-None Law
Once threshold has been reached, an \__________ \______________ will happen
The size of the stimulus will not affect the size of the action potential; it will always reach \________mV
The size of the stimulus will not affect action potential duration

action potential
+30

A stronger stimulus will make action potentials occur more frequently (frequency modulated)
A stronger stimulus may also activate more neurons in a nerve which is called \_____________.

recruitment (frequency-related)

Action potentials can only increase in frequency to a certain point. There is a \___________ period after an action potential when the neuron cannot become excited again

The absolute refractory period occurs during the action potential. Na+ channels are \_________ (not just closed)

The relative refractory period is when K+ channels are still open. Only a very \________ stimulus can overcome this. Each action potential remains a separate, all-or-none event

refractory
inactive
strong

\____________ properties is the ability of neurons to conduct charges through their cytoplasm

Poor due to high \____________ resistance to the spread of charges and leaking of charges through the membrane

Neurons could not depend on cable properties to move an impulse down the \______ of an axon.

Cable
internal
length