Chapter 2; Neurobiology Flashcards
How many neurons in the human brain?
85-100 billion
Neurobiology is the study of the ____ ____ and how the ____ works. Basic operating principals of the ____ ____, right down to ____ and ____ properties.
nervous system
brain
nervous system
electrical, chemical
The vertebrae neuron is ____ and measures approximately ____ ( _ x _ ^_ m) in diameter and up to more than a ____ in length.
microscopic
10 to 20 microns
1 x 10^-6, meter
Neurons are ____ packed.
densely
Glia: equal ____ to the neuron, and non-____ ____ cells.
volume
non-neuronal supporting
What is evolutionarily conserved in regard to the neuron?
unchanged; the neuron is basically the same across all vertebrate animals
Neurons are the ____ and ____ units of the nervous system.
structural
functional
A nerve is ____ and consists of a bundle of dozens to hundreds of ____ packed together in a ____ ____ ____.
macroscopic
neurons
connective tissue sheath
The neuron is a ____ cell used for ____ information between the ____ and your ____ from one region to another.
specialized
transmitting
brain
body
How is the neuron information transmitted (what form)?
electrochemical signals
Neuron sends information in what 2 ways?
Conduction of electrical impulses
Release of chemicals
What is the conduction of electrical impulses?
Action Potential
What is the release of chemicals?
Neurotransmitters
What are recognized and received by another neuron?
Neurotransmitters
How does the typical neuron send neurotransmitters? And what is it?
Across the synapse
Microscopic gap between cells
What does the postsynaptic neuron do with the chemical signal (neurotransmitter)? What does this trigger? And that activates a release of what?
Converts to an electric signal
An action potential
It’s own neurotransmitters
What are the 4 main components of a neuron?
Dendrites
Soma
Axon
Terminal Buttons
The dendrites receive and recognize ____ released from other cells and ____ the ____ signal into an ____ ____ signal.
neurotransmitters
convert
chemical
intracellular electrical
What signal travels down the dendrites? To what?
Electrical
Soma
What contains all of the machinery for manufacturing neurotransmitters?
Soma
What transmits the electrical signal from the dendrites?
Soma
What are the two main functions of an axon?
Transport neurotransmitters from soma to terminal boutons
Generate and conduct action potential down to the terminal buttons
Terminal buttons are responsible for ____ ____ for eventual release in response to arrival of an ____ ____ .
storing neurotransmitters
action potential
3 ways neurons are classified
shape
function
location
____ neurons compromise majority of nervous system.
multipolar
____ neurons have ____ processes which functions with a ____ end and a ____ end. Where are these found?
Bipolar Two Sending Receiving The retina of the eye
What process is the sending end called?
axonal process
What process is the receiving end called?
dendritic process
____ have a ____ process attached to the soma. Where is this found?
Unipolar
Single
Sensory System
What are the four components of neuron covered in?
Cell membrane
The cell membrane is a ____-____ membrane that ____ the entire ____.
double-layered
envelops
neuron
What is the cell membrane composed of?
Phospholipid Bilayer
The phospholipid bilayer consists of ____ phosphate molecules (“head”) sandwiching ____ fatty acids (____) in between (“____”).
polar
non-polar
lipid
tail
Phosphate heads are ____ or attracted to ____ which is also polar.
hydrophilic
Attracted to water
Polar
Describe phosphate head and tails in relation to water?
Head interacts with water in extracellular space in cytoplasm of cell.
Tail avoids water and is protected by phosphate head.
The ____ ____ is a specialized ____ (small “organ” of the cell) that regulates movement of ____ in and out of the ____ which allows ____ between the ____ space of a cell’s ____ and controlling the ____ changes of the neuron.
cell membrane organelle molecules neuron communication extracellular interior electrical
____ permeability:
____ , ____ , and/or ____ molecules do not go through the ____ by ____ (or ____ ).
semi large polar charged membrane diffusion osmosis
What is a lipid?
fatty acids and insoluble in water
Difference between polar and nonpolar?
Polar: electrons unequally shared by two atoms
Non-polar: electrons equally shared by two atoms
What kind of molecules readily diffuse through the membrane?
Small or lipid-derived molecules
What gives the cell membrane the ability to regulate cellular communication?
Membrane-Embedded Protein (MEP)
What three ways do the cell get the molecules through the membrane?
Transporter, Channel, and Receptors
How does the Transporter work (MEP)?
It functions like a pump. It spans the thickness of the membrane and uses energy (ATP) to actively transport nondiffusible molecules into and out of the cell.
What is ATP and what is it the source of?
Adenosine triphosphate; the cell’s source of energy
How does a Channel work (MEP)?
They are specific for particular ions and can be opened and closed depending on conditions. This is selective permeability.
Which MEP does not transmit molecules across the membrane?
Receptors
How does a Receptor work (MEP)?
Like a lock on a door. A molecule, like a neurotransmitter, connects or binds to a receptor that is specific for that molecule.
With a Receptor (MEP), after the molecule is binded, what happens?
The receptor changes, sends a piece of that information into the cell, letting the cell know the message from the extracellular space has been “received.”
What are amino acids?
Building blocks of proteins
What are most neurotransmitters derived from?
amino acids
Where are neurotransmitters made?
In the vicinity of the nucleus of the cell
Where is the nucleus of the cell?
Found in the soma
What structure of the cell contains chromosomes?
The nucleus
What are chromosomes?
Densely packed strands of DNA
Many neurotransmitters consist of a single ____ ____ that has been modified slightly.
amino acid
Neurotransmitter serotonin is just a modification of the dietary amino acid ____
tryptophan
In making of a neurotransmitter, what is split apart and what is it transcribed into?
the double helix of the DNA
mRNA (messenger ribonucleic acid)
mRNA is a ____ ____ of ____ with ____ pairs that correspond to the ____ ____ molecule.
single strand
nucleotides
base
parent DNA
In making of the neurotransmitter, after the DNA is transcribed into mRNA, what is translated to assemble chains of what?
The mRNA is translated to assemble changes of amino acids
What determines which amino acids are to be taken from the cytoplasm and assembled into proteins?
The unique sequence of nucleotides
The ____ is another intracellular ____ that runs down the ____ reading three ____ sequences at a time that correspond to a specific ____ acid.
Ribosome organelle mRNA nucleotide amino
A ____ is a particular sequence of ____ that codes for the production of a specific ____ or ____ .
gene
nucleotides
protein
trait
Proteins are ____, like muscle or keratin, or ____, like enzymes.
Structural
Regulatory
____ proteins regulate ____ reactions, controlling a wide variety of processes such as ____ synthesis, ____ (ie. breakdown), and thousands of other ____ functions.
Regulatory chemical neurotransmitter degradation metabolic
Starting with the soma, walk me through the steps to a neurotransmitter?
Soma to cell body to nucleus To chromosomes (densely packed DNA) and DNA splits and transcribed to mRNA that is translated into Amino Acids
Where are the newly synthesized neurotransmitters processed?
The Golgi Apparatus
What is the Golgi Apparatus?
Encloses the neurotransmitters inside a synaptic vesicle
What is a synaptic vesicle?
A bag of membranes that contains the neurotransmitters
Neurotransmitters have to be ____ (ie. stored and protected) inside of ____ in order to protect them from ____ ____.
sequestered
vesicles
degradative enzymes
What are degradative enzymes, and what can this lead to?
break down and permanently alter chemical structure, which can lead them to be inoperative
Where are the neurotransmitters sent to after being stored into the vesicles?
They are sent to the terminal buttons.
Where are neurotransmitters stored?
Terminal buttons
When the Golgi is complete, organelles known as ____ function as a conveyer belt for ____ vesicles down the length of the ____ through a process called ____ ____ .
microtubules
transporting
axon
axoplasmic transport
The vesicles that store the ____ keep them stored until they release the ____ into the ____ .
neurotransmitters
neurotransmitters
synapse
The arrival of what causes the release of a packet of neurotransmitters?
Action potential
What two things travel down the axon towards the terminal? Which is faster?
Synaptic vesicles Action Potentials (faster)
Action Potentials represent movement of ____ charge and travel down the ____ in time measured in ____ .
electrical
axon
milliseconds
Axoplasmic transport takes ____ to ____ to occur and involves ____ movement of ____ .
hours
days
physical
molecules
Half of the volume of the brain consists of ____ - ____ cells known as ____ which are also known as ____ cells.
non-neuronal
glia
supporting
What are the four kinds of Glial Cells?
astrocytes (star-cell)
Microglia
Eligodendrocytes
Schwann
Which type of glial cells provides nutritional and physical support for neurons?
Astrocytes
Which type of glial cell are small, branches cells that wrap their tentacles around capillaries?
Astrocytes
When a neuron dies, which glial cell secretes extracellular material that replaces the lost neuron with scar tissue (sclerosis)?
Astrocytes
What glial cell helps the immune system rid the brain of foreign material and cellular debris by holding on to and presenting these substances to the macrophages of the immune system that engulf (phagocytose) the material in order to remove it?
Microglia
What glial cell has processes that wrap around axons and create the myelin sheath?
Oligodendrocytes
What is an insulative covering?
The myelin Sheath
Myelin is a ____ substance that insulates ____.
fatty
axons
What is the CNS?
Central nervous system
What is the PNS?
Peripheral nervous system
The PNS contains only ____ cells (a glial cell) which are the analogs of the CNS’s ____ .
Oligodendrocytes
What enables action potentials to be conducted down the axon very efficiently and rapidly?
The myelin sheath
Which type of vertebrate completely lacks myelin?
Invertebrates
What is a physical parameter that “resists” the flow of electrical signals?
Resistance
Resistance can ____ down signals and make them ____ across distance.
slow
dissipate
Vertebrates have ____ resistance? (low/high)
high
Do vertebrate neurons conduct action potentials at a faster rate compared with invertebrates or slower? Why?
Higher
Special properties of the myelin sheath
Technical term for cutting axons is what?
Denervation
In CNS, do denervated axons attach to their target?
No, they do not reattach.
The spinal cord and brain consist of a very ____ and complex array of ____ .
dense
neurons
Differences in post-denervation recovery are conferred by major differences in the ____ in CNS vs PNS
glia
What is the fundamental different between the two myelin sheath-prodcuing cells? Examples of oligodendrocyte and Schwann
how they wrap around the axon.
Oligoendrocyte has several branches that warps around handful of axons so when the neuron is denervated, the branches wither back and if there is an attempt to grow back there is no guide.
Schwann wraps its whole body around a single axon and remains in place after denervation, when it grows back there is a path of tunnels still in tack.
Which has better neuronal recovery: CNS or PNS?
PNS
What triggers a neurotransmitter’s release from the synaptic vesicles waiting in the terminal boutons?
An action potential
Neurons are ____ batteries (in contrast to nerves that are ____ )
microscopic
macroscopic
The neuron stores ____ energy
potential
What is potential energy?
Energy that is stored-up, to allow for its later release
Potential energy in a neuron comes in the form of what?
membrane potential
Membrane Potential is defined as a difference in ____ on the ____ ( ____ ) of a cell vs. the ____ of the cell ( ____ ____).
voltage inside cytoplasm outside extracellular fluid
What is it called when the membrane potential is at rest or not doing anything in particular, not firing an action potential?
Quiescent
The membrane potential registers at ____ ____ (mV0.
-70 millivolts
The reading of -70mV represents the ____ ____ .
Resting potential
The membrane potential is the difference in ____ whereas the resting potential represents the ____ .
voltage
-70mV
What is the goal between the soma to the terminal?
To fire an action potential
It is the deviation from 0mV that represents and gives rise to the potential ____ .
energy
The action potential comes in the form of a release of the stored ____ ____ or a resting cell and a tremendous positive deviation in ____ ____ away from the negative ____ ____ .
potential energy
membrane potential
resting potential
The action potential will represent a swing from ____ mV all the way up to about ____ mV.
-70
+40
Every living cell contains ____ and is bathed in ____ fluid.
cytoplasm
extracellular fluid
Cytoplasm and extracellular fluid contain a large number of ____ .
molecules
Particular important to membrane potential are the charged elemental particles knows as ____ .
ions
Positively charged ions are ____ and negatively charged ions are ____ .
cations
anions
Extracellular fluid is basically saline as it compromised of ____ ( ____+)( ____(type of ion)), and ____ ( ____ -)( ____ (type of ion)) ions.
sodium Na+ cation
Chloride cl- anion
There are Na+ and Cl- ____ the cell as well as other ions inside and outside of the cell (like ____ ( ____ +)), organic ____ ( ____ and ____ acids), and ____ ( ____ ++).
inside Potassium, K+ anions proteins and amino acids Calcium, Ca++
The differential distribution of specific ions on the ____ and ____ of the neuron will give rise to the ____ ____ , and actual movement of ions through the ____ ____ will generate the ____ ____ .
inside outside membrane potential cell membrane action potential
What is the push or pull on ions that compels them to move in a direction into or out of a cell?
Force
What is the actual movement of ions during an action potential?
Flux
What is the difference between force and flux of ions?
Force is the compelling push or pull whereas the flux is the actual movement during action potential
Extracellular fluid (saline) means that what will be found outside of cells due to that higher concentration (measured in ____ )?
Na+ and Cl-
Na+ and Cl- ____ in a solution.
dissociate
____ + operates in nearly every way opposite of Na+
K
If Na+ is found in a higher concentration outside the cell, what is found in higher concentration inside the cell?
K+
What are the two forces that act on ions?
Concentration gradient (CG) and electrostatic pressure (EP)
In a concentration gradient, the ions will want to move from areas of a ____ concentration to a ____ concentration.
higher
lower
In a concentration gradient, ions strive towards a ____ state.
balanced
Concentration gradient or the ____ of ____ .
force of diffusion
The size of the ____ for a given ion can be measured ____
force
empirically
Forces are measured in ____ (in ____ values)
mV
absolute
CG Na = ____ mV
50 in
CG Cl = ____ mV
70 in
CG K = ____ mV
90 out
The cell membrane is polarized, hyperpolarized(more neagative), or depolarized(more positive)?
Polarized
The ____ ____ is determined by the uneven distribution of ____ ( ____ particles) between the inside and outside of the cell, and by the different ____ of the membrane to different types of ____
resting membrane ions charged permeability ions
Why can’t the ions pass directly through the hydrophobic lipid regions of the membrane?
Because they are charged
What do charged ions use to get across the membrane?
Specialized channel proteins that are hydrophilic tunnels
Some channels known as ____ channels are open in resting neurons. Others are closed in resting neurons and only open in ____ to a signal.
leak
response
The resting ____ ____ depends mainly on movement of ____ + through ____ ____ channels.
membrane potential
k+
potassium leak
What are the rules of attraction for ions?
Opposites attract and charges repel
Ions get pushed or pulled due to their ____ ____ (or forces due to charge)?
electrostatic pressure
What is the resting potential of the neuron?
-70mV
What is the mV of the inside of the cell?
-70 mV
Is the inside of the cell negative of positive?
negative
EP Na = ____ mV
70 in
EP Cl = ____ mV
70 out
EP K = ____ mV
70 in
What does net forces mean?
sum total forces
Calculate the net force by ____ the individual net forces per ion, or ____ if the two forces are in the opposite directions.
adding
subtracting
NF Na = ____ mV
120
NF Cl = ____ mV
0
NF K = ____ mV
20
The values and forces can vary across species. The net ____ and relative ____ are consistent across species. The numbers are not a specific representation.
direction
magnitude
Forces determine the actual movement of ions across the cell membrane is known as what?
Ion Flux
How does the flux occur?
In the same direction as the force.
A property of a membrane is ____ .
permeability
What is permeability?
The ease with which ions can pass through the membrane.
Charged particles like ions do not readily ____ through ____ ____ .
move
cell membrane
The movement of ions into and out of the cell is completely impeded by the very structure of the ____ ____ .
Lipid bilayer
What type of MEP (membrane embedded protein) confers some permeability under certain situations?
Ion Channels
Ion channels are ____ molecules that are ____ in and ____ the thickness of the ____ ____ .
protein
embedded
transverse
cell membrane
What serves as passageways for ions to travel through the cell membrane allowing for influx and efflux?
Ion Channels
What is an influx?
inward flux
What is an efflux?
outward flux
Are the ion channels simply just tunnels? Why?
No, they have specificity
Ion channels allow ____ for only ____ type of ____ .
flux
one
ion
The ____ of an ion channel can be modulated up or down by ion channel ____ .
permeability
gates
Channel gates are ____ structures within the channel that can close off a channel or open up to allow passage of ____ depending upon ____ .
protein
ions
conditions
What conditions are depending on a channel gate opening or closing?
Membrane voltage or if a neurotransmitter is being received
When channel gates are ____ , ____ is high, and ion ____ proceeds.
open
permeability
flux
When channel gates are ____ , ____ is low, and ion ____ is impeded or stopped.
closed
permeability
flux
Ion channels and gates serve to give the cell ____ ____ .
selective permeability
Selective permeability is selectivity for particular ____ under ____ conditions, depending on the status of the ____ .
ions
specific
gates
Cl- has a net force of 0 which means there is ____ ____ flux, which means it is in a state of ____
no net
equilibrium
Cl- ions are ____ and ____ at the same rate, which means they are in ____ .
influxing
effluxing
balance
At rest, Cl- ____ is high, which means the gates are relatively ____ .
permeability
open
Instead of not moving, Cl- readily moves ____ and ____ of the cell but at ____ rates, hence equilibrium.
in and out
equivalent
Na+ is sitting ____ the cell, with this large inward ____ at rest, you have to have low ____ to thwart Na+ from constantly rushing into the cell.
outside
force
permeability
The ____ to Na+ at rest is very ____ and resists the large ____ .
permeability
low
force
K+ is trying to ____ the cell with comparatively much less ____ .
escape
force
Having ____ permeability for K+
high.
Does Cl- contribute to the resting potential?
Not really.
Na+ is attempting to ____ its way into the cell but is resisted by ____ ____ .
push
low
permeability
K+; a small outward ____ pushing against low resistance or ____ permeability.
force
high
Small amount of flux is a ____ .
leak
At resting potential, Na+ leaks ____ and K+ leaks ____ .
in
out
The unequal distribution of ions would dissipate if the leak was unchecked which result in a drift of -70mV to 0 and the loss of ?
resting potential, losing the potential energy
What is the cell’s way of compensating for the leakage -what process?
Active Transport.
Active transport pumps the leaked ions in the ____ direction of the leak, just enough to compensate for the leakage.
opposite
In active transport, a ____ uses ATP to actively ____ molecules into and out of the cell.
transporter
pump
What is the particular transporter called in active transport (compensating for the leaking)?
Na-K transporter
The ions are pumped in a ____ ratio, as ____ leaks in slight more than ____ leaks out.
3:2
Na+
K+
The Na-K transporter has to continue running to maintain the ____ ____ in an ionic balance called which differs from ____ in that the steady state require the input of ____.
resting potential
steady-state
equilibrium
energy
If a cell is deprived of ____ , then not enough ATP (Adenosine triphosphate; the cell’s source of energy) can be manufactured to provide ____ for the Na-K transporter.
oxygen
energy
If the Na-K transporter is shut down, the ____ ____ would degrade toward ____ mV, and there would not be enough ____ ____ to fire an ____ ____ and therefore transmit “ ____ “. This means, the neuron ____ ____ .
resting potential 0 potential energy action potential information shuts down
It takes a continuous expenditure of ____ to maintain the ____ ____ of the ____ ____ necessary to subsequently do some work (ie. generate an ____ ____ ).
energy
potential energy
resting potential
action potential
An ____ ____, once triggered, does not rely upon the input of more energy - it relies completely upon the ____ previously ____ .
action potential
energy
stored
In a neuron, it takes work to maintain ____ .
rest
The Equilibrium Potential (EqPot) is measured empirically in a laboratory. It is defined as the ____ ____ at which a particular ion reaches its own unique ____. EqPot is when the ____ and ____ for a given ion would be ____ , but in ____ directions.
membrane potential equilibrium CG EP equivalent opposite
The EqPot is therefore the ____ ____ at which the ____ ____ equals zero.
membrane potential
net force
EqPot Na+ = ____ mV
55
EqPot Cl-= ____ mV
-70
EqPot K+= ____ mV
-75
What forces change during ion flux and how?
Electrostatic Pressure, in reverse
Understanding EqPot. Na+ were to ____ into the cell, then the inside of the cell becomes more ____ creating a diminution of the size of the ____ ____ . At a high enough membrane potential, the EP will ____ and become ____ , eventually becoming equal in size but ____ direction to the concentration gradient. In other words, the membrane potential has to go as high as +55mV in order for Na+ to reach its ____ .
influx positive electrostatic pressure reverse larger opposite equilibrium
____ ____ represents a dramatic increase in ____ that reverses ____ of the cell.
action potential
voltage
polarity
The change in the ____ ____ in the ____ direction is called depolarization.
membrane potential
positive
The membrane potential will chance from ____ ,pass ____ ,move into the ____ range, approaching ____ mV, and then return to ____ , all in the matter of less than ____ ms. This burst is known as a ____, the “ ____ of ____ “ used by the ____ ____ to ____ .
rest zero positive \+40 rest 3 spike unit of information nervous system communicate
The sending of the ____ down the axon to the ____ causes ____ to be released.
spike
terminals
neurotransmitters
Action Potential consists of simply a ____ of ____ ____ - energy that was previously ____ during ____ ____ (remember the ____ - ____ transporter?).
release potential energy stored resting potential Na-K
Na+ sits ____ the cell with a large ____ ____ that is kept at bay by ____ permeability.
outside
inward force
low
Na+ wants to move into the cell but the gates are mostly ____ at ____ preventing Na+ from getting through the ____ .
closed at rest
channels
Na+ wants to bring the cell to ____ .
EqPot 55mV
Na+ represents the ____ ____ that will be released to form the ____ ____ .
potential energy
action potential
What is the region of the cell between the soma and the axon that is really the beginning of the Axon?
Axon Hillock
Axon Hillock represents the location on the cell where an ____ ____ is first generated.
Action Potential
What is the first region of a cell that has the kinds of channels that allow Na+ to come rushing in the cell to create an Action Potential?
Axon Hillock
What is the particular condition that allows the gates that are mostly blocking these channels at rest to suddenly begin to open?
When the membrane potential reaches -60mV
When the membrane potential reaches the ____ of - ____ mV, the gates ____ up and allow ____ to influx.
voltage
-60
open
Na+
- ____ mV represents a ____ voltage necessary for triggering an ____ ____ . This membrane potential is called the ____ ____ ____ or action potential ____ .
60 voltage action potential threshold of excitation threshold
What decides whether or not to fire an action potential?
The axon hillock
What is the decision point of the cell?
The axon Hillock
What causes the gates to open?
The voltage
When the ____ ____ exceeds the threshold, the ____ structure of the gate ____ changes, causing the Na+ ____ to increase; this allows Na+ to ____ .
membrane potential chemical proteins permeability influx
What Na+ channels trigger change to their permeability by changes in membrane voltage that bring the membrane potential above the threshold?
Voltage-gated
Having a ____ gives the action potential a unique feature.
threshold
Action potential is triggered in a “ ____ or ____ “ manner. There is no turning back.
all or none
An action potential comes from the ____ of Na+ via ____ - ____ Na+ channels who gates ____ when the membrane potential reaches the ____ of ____ .
influx
voltage-gated
open
threshold of excitation
Where do voltage changes happen before the hillock?
in the soma and dendrites
Where does a cell typically receive information from other cells?
The reception of neurotransmitters
What is the essence of neuronal communication? To release ____ from its ____ to the next neuron.
neurotransmitters
terminal
In order to trigger an action potential in a post-synaptic neuron, the binding of the neurotransmitter must be ____ into an ____ ____ that gets transmitted to the hillock.
transformed
electronic signal
Neurons transform received ____ information (binding the ____ in dendrites) into ____ information (in the form of ____ ____ in the axon) and then back again to ____ information - in the form of release ____ from the terminal.
chemical neurotransmitters electrical action potentials chemical neurotransmitters
What is the type of neurotransmitter that actives cells (ie. leads the receiving cell closer to firing an action potential)?
An excitatory neurotransmitter.
Excitation refers to moving the ____ ____ closer to the ____ of ____ and thereby ____ the likelihood of the next neuron firing an ____ ____ .
membrane potential
threshold of excitation
increasing
action potential
An excitatory neurotransmitter ____ to a ____ and triggers the ____ to have an effect on ____ + ____ , namely to cause Na+ ____ to ____ up (a small number of them) allowing Na+ to ____ causing a small ____ in the dendrites. That receptor is called ____ (causing a change in ions) which means it is ____ with an ____ channel and thus able to have an effect on the ____ ‘s gates.
binds receptor receptor Na+ channels gates open influx depolarization dendrites ionotropic coupled ion channel
The resulting depolarization that occurs in the dendrites and soma is called a ____ ____ .
post-synaptic potential (PSP)
The post-synaptic potentials are triggered by a ____ binding to an ____ receptor, which, in turn, modifies ____ ____ gates; this configuration is referred to as ____ - ____ .
neurotransmitter
ionotropic
ion channels
ligand-gated
A ____ is a generic word for any chemical that binds to a receptor.
ligand
If the gates that are opened are ____ channels (allowing ____ to ____ at ____ ____ ) then an ____ ____ ( ____ ) is triggered, meaning that the membrane potential is elevated closer to the ____ of ____ (and therefore more likely to fire an ____ ____ .
Na+ Na+ influx resting potential excitatory PSP (EPSP) threshold of excitation action potential
EPSP (excitatory post-synaptic potentials) are subthreshold ____ (individually, they don’t typically push the ____ ____ above the - ____ mV threshold).
depolarizations
membrane potential
-60 mV
When ____ raise the membrane potential a small deviation and do not exceed the threshold of ____ , the membrane potential returns to ____ as time passes.
depolarizations
excitation
rest
The membrane potential exceeds the ____ and triggers and ____ ____ because of the adding of all of the ____ together.
threshold
action potential
EPSP
When the ____ is reached at the axon hillock, then an ____ ____ will be triggered.
voltage
action potential
The process of adding EPSPs together is called ____ .
summation
EPSPs summate through a combination of ____ ____ (close in time) and ____ ____ (from multiple inputs being received at different parts of the cell).
temporal summation
spatial summation
EPSPs are triggered in the ____ and must travel down them and across the ____ of the ____ . When they travel through the ____ they spread ____ (in all directions) and eventually reaching the ____ .
dendrites cytoplasm soma cytoplasm omnidirectionally hillock
As EPSPs spread or ____ across the cell, they lose ____. This ____ is lost due to ____ . With EPSP conduction, resistance of the ____ causes the ____ change of the SPSP to diminish back towards the resting potential. This type of conduction is called ____ ____ , meaning the ____ change ____ over ____ as the EPSP spreads.
conduct energy energy resistance cytoplasm voltage decremental conduction voltage decreases distance
EPSPs are always ____ ; as long as the sum of the EPSPs exceeds the ____ of ____ , then you will get an ____ ____ .
summating
threshold of excitation
action potential
EPSPs can consists of ____ of various sizes ( ____ ), which is referred to as a ____ response. What would make a PSP large would be a release of large amounts of ____ onto that cell. A small PSP would mean that small amounts of ____ were released.
depolarization amplitude graded neurotransmitters neurotransmitters
IPSPs are ____ ____ ____ ____ .
inhibitory post-synaptic potentials
IPSPs are triggered by an ____ ____ .
inhibitory neurotransmitter
IPSPs work to bring the membrane potential further away from the ____ of ____ (more ____ ) and therefore reduce the cell’s changes of firing an ____ ____ .
threshold of excitation
negative
action potential
Na+ wants to ____ until 55+ mV.
influx
What are anxiolytic?
anxiety-reducing drugs
Anxiolytic drugs promote the ____ of ____ and tone down activity in parts of the brain subserving anxiety reactions.
influx
Cl-
The nuerotransmitter ____ ____ ____ ____ ( ____ ) is an ubiquitous (ie. ____ ) neurotransmitter in the brain that regulates overall activity of ____ ____ . ____ accomplishes this by modulating ____ - conductance.
gamma amino butyric acid GABA brain circuitry GABA Cl-
____ + ____ for IPSPs.
K+ efflux
____ + ____ lowers the membrane potential, giving rise to ____ .
K+ efflux
IPSPs
Neurons may receive a mixture of ____ and ____ . When they summate at the hillock, both positive and negative potential changes will get algebraically added and subtracted together. Whatever the ____ ____ happens to add up to at the ____ is the key. it will determine whether or not the ____ - ____ ____ + channels open up and trigger the ____ ____ .
EPSPs and IPSPs membrane potential hillock voltage-gated Na+ action potential
The membrane potential ____ from rest to a very high positive level, and then it dives back down to rest ( ____ ).
depolarizes
repolarization
K+ wants to bring the MP to ____ mV.
-75mV
Na+ wants to bring the MP to ____ mV.
55mV
Once the threshold is reached, the ____ starts off slowly and then very quickly depolarizes rather dramatically ( ____ ____ ).
depolarization
exponential acceleration
The ____ - ____ ____ + channels begin to open up and allows for some Na+ ____ .
voltage-gated
Na+
influx
The Na+ channels ____ open up at the same time as it happens ____ time. Na+ ____ , the membrane potential ____ , causing more ____ to open, leading to more Na+ ____ , and so on.
don't over influxes depolarizes channels influx
Slowing down of depolarization is partly because the Na+ ____ are starting to close and therefore slowing down the ____ of Na+. And then the ____ +channel opens and accelerating rapidly which allows for the ____ + ____ .
channels influx K+ K+ efflux
The membrane potential dips below the rest is called ____ .
hyperpolarization
Action Potentials are generated in the ____ ____ and travel to the ____ to trigger the release of ____ .
axon hillock
terminal
neurotransmitters
Starting with the ____ of the Na+ and ____ of K+ at the hillock, an ____ ____ will be released at that place in the cell. To conduct an ____ ____ down the axon, there is going to be a trigger of new ____ ____ sequentially along the length of the axon - not the same ____ ____ . This ____ aspect of it dictates that once it is triggered at the ____ ,it will conduct down the axon and create ____ ____ in the terminal.
influx efflux action potential action potential action potential action potential regenerative hillock action potentials
Resting Potential requires the continuous ____ of ____ ( ____ - ____ transporter requires ATP), whereas the action potential requires no additional ____ as it relies upon the ____ stored up during resting potential.
input of energy
Na-K
energy
energy
Action potentials spread a wave of ____ triggering the influx of na+ and the efflux of k+ creating a new action potential. Think of it like a ____ or a pulse.
depolarization
spike
There is no ____ ____ in invertebrate nuerons.
myelin sheath
The ____ ____ allows neurons to be very small in ____ by speeding up ____ of the action potentials.
myelin sheath
diameter
conduction
The myelin sheath has gaps in it separated by fixed segmental lengths of ____ . These gaps, known as ____ ____ ____ , represent places on the axon not covered by ____ and therefore have membranes exposed to the extracellular space; the ____ allow for influx/efflux of ____ as the ____ does not allow for ion flux.
myelin nodes of ranvier sheath nodes ions sheath
When an action potential is generated, local membrane ____ occurs.
depolarizations
PSPs conduct ____ .
omnidirectionally
Action potentials always travel in ____ ____ and ____ the terminal. Phenomenon is called ____ conduction.
one direction
terminal
orthodromic
____ period is when the voltage-gated channels need a little time to reset themselves.
refractory
An action potential releases the neurotransmitters from the terminal through ____ .
Exocytosis
When the action potential reaches the terminal, a new set of ____ - ____ ion channels opens, this time allowing the influx of ____ +. ____ + is needed to promote the actions of an enzyme as an ____ ____ . Once promoted, this enzyme starts the process of ____ .
voltage-gated Cl+ Cl+ enzymatic cofactor exocytosis
Exocytosis:
The synaptic vesicles ____ to the presynaptic membrane. The vesicles make physical contact with the presynaptic membrane and ____ together. Then the cell membrane-synaptic vesicle fusion point forms the ____ ____ and then pulls apart, emptying the contents of the ____ into the ____ ____ . Now the vesicle has become part of the ____ ____
migrate fuse omega complex vesicle synaptic cleft presynaptic membrane
Vesicles and cell membranes are constructed of the same ____ ____ .
lipid bilayer
When the membrane pinches off internally and forms a new vesicle to avoid enlarging, recycling the vesicular membrane, what is that process called?
pinocytosis
Does a vesicle have a fixed quantity of neurotransmitters?
Yes
What law states that the higher rates of action potentials arriving at the terminal translate into more Ca++ influx, which in turn leads to more exocytosis of synaptic vesicles?
Rate
____ function to help the cell releasing the neurotransmitter monitor and regulate the amount of neurotransmitter being released.
autoreceptors
What is the strength of binding called?
binding affinity
What is the process when a neurotransmitter is deactivated by pumping them back into the pre-synaptic cell via a transporter? It actually removes the NT from the synapse and regulates the amount that binds to receptors. Also recycles NTs which reduces the amounts that need to be manufactured.
Reuptake
____ ____ change the chemical structures of neurotransmitters so they no longer are recognized as ligands by the receptors and can be broken down to their constituent compounds ( ____ ____ ____ ).
enzymatic degradation
single amino acids
Do some neurotransmitters diffuse in the extracellular away from the synapse?
Yes
Name four fates of neurotransmitters
Diffuse in extracellular space
Enzymatic Degradation
Reuptake
Binding to post of pre synaptic (pre being autoreceptors)
____ ____ ion channels open in response to voltage (i.e. when the cell gets depolarized) where as ____ ____ channels open in response to a ligand (some chemical signal) binding to them. … The ligand gated channels open up and allow the influx of sodium, which depolarizes the cell.
Voltage-gated
ligan gated
