Item 4 Flashcards
Long-distance communication is a function of the _ system and the nervous system
endocrine
The _ nervous system (_NS) consists of the brain and spinal cord
central
_ information is received and processed by _ory organs and the viscera to determine the state of the external environment
sensory information; sensory organs
The internal environment is considered _ information of the CNS
VISCERAL
The _ integrates sensory and visceral information to make decisions on appropriate actions then sends instructions to certain organs instructing them to perform appropriate tasks
CNS
The _NS is also the site of:
learning
_
emotions
thoughts
language
other complex functions
memory
The _NS consists of neurons that provide communication between the _NS [different!] and organs throughout the body
PNS; CNS
The PNS can be subdivided into two divisions:
_erent
_erent
afferent; efferent
Neurons of the _erent division transmit sensory and visceral info from the organs to the CNS
afferent
Info transmitted to the CNS includes the _ senses, associated with the skin, muscles and joints
somatic senses
Info transmitted to the CNS includes the _ senses, associated with vision, hearing, equilibrium, smell, taste)
special senses
Info transmitted to the CNS includes visceral information associated with the internal environment such as:
fullness of the stomach
blood pressure
…
blood pH
Neurons of the _erent division transmit information from the CNS to organs in the periphery
efferent
Neurons of the efferent division transmit information from the CNS to organs in the periphery, called _ organs
effector
_ organs perform functions in response to commands from neurons
effector
Effector organs perform functions in response to commands from neurons; they’re usually muscles and _
glands
A neuron capable of transmitting messages to an effector organ or receiving info from a sensory organ is said to _ate that organ
innervate
The efferent division can be subdivided into two main branches:
the somatic/voluntary NS and
_/involuntary NS
autonomic/involuntary NS
The efferent division can be subdivided into two main branches:
the _/voluntary NS and
autonomic/involuntary NS
somatic/voluntary NS
The somatic NS consists of the _ _ns, which regulate skeletal muscle contractions
motor neurons
The _ _ _ consists of neurons that regulate the function of internal organs and other structures
autonomic NS
The Autonomic NS consists of neurons that regulate the function of internal organs and other structures, such as sweat glands and _ _, that are not under voluntary control
blood vessels
The autonomic nervous system can be divided into two branches:
the _etic NS
the _etic NS
parasympathetic NS and sympathetic NS
The _ NS comprises of an intricate network of neurons in the gastrointestinal tract that can function independently of the rest of the nervous system but communicates with the autonomic NS
ENTERIC nervous system
The NS contains two main classes of cells:
neurons
_ _
glial cells
The neuron is the _ _, the smallest unit of a tissue that can carry out the tissue’s reason for existing
functional unit
Neurons are _ cells, capable of producing large, rapid electrical signals
excitable
Neurons are excitable cells, capable of producing large, rapid electrical signals called _ _
action potentials
Glial cells, which account for _% of the cells in the NS, provide various types of support to the neurons, including structural and metabolic support
90%
Neural processes or _ extend from the cell body
neurites
Two types of neurites extend from the cell body:
dendrites
_
axons
The cell body or _ contains the cell nucleus, endoplasmic reticulum, Golgi apparatus, and most of the free ribosomes
soma
_ are located in the cell body, but also throughout the body
mitochondria
The cell body carriers out most of the functions that other cells perform, such as protein synthesis and cellular _
metabolism
T or F: mature neurons do not retain their nuclei, but they keep their ability to undergo cell division
FALSE! mature neurons retain their nuclei, but lose their ability to undergo cell division
T OR F: adults have all the neurons they will ever have
true
Can new neurons develop from undifferentiated cells in the adult human brain?
yes
Undifferentiated cells or _ cells can develop in a few areas of the adult human brain
stem cells
_ branch from the cell body and receive input from other neurons at specialized junctions
dendrites
Dendrites branch from the cell body and receive input from other neurons at specialized junctions called _
synapses
T OR F: cell bodies themselves can receive input at synapses
true
cell bodies can receive input at synapses as well as dendrites that branch from the cell body
_ cells are star-shaped
stellate
The extent of _ is an indication of the number of synapses with the neuron, as the majority of synapses occur there
branching (i.e., dendrites)
The nerve fibre, or _, serves to send information (unlike a dendrite which receives information)
axon
T OR F: neurons can have several axons
false
generally they only have one, but axons can branch, sending signals to more than one destination
The branches of an axon are called _; the extent of branching varies among neurons and is indicative of the amount of communication with other cells
collaterals
The axon function in rapid…over relatively long distances in the form of electrical signals
rapid transmission of information
The axon function in the rapid transmission of information over relatively long distances in the form of electrical signals, i.e., _ _
action potentials
Action potentials are brief, large changes in membrane potential during which the _ of the cell becomes positively charged relative to the _
inside of the cell becomes positively charged relative to the outside
i.e., positive membrane potential due to action potentials
T OR F: the beginning of an axon are specialized structures called the axon terminal and the end is the axon hillock
false - axon hillock is the beginning, axon terminal is the end of an axon
T or F: the axon hillock is specialized in most neurons for the initiation of action potentials
true
the _ _ is specialized to release neurotransmitter on arrival of an action potential
axon terminal
The axon is specialized to release neurotransmitter on arrival of an action potential. The released neurotransmitter molecules carry a signal to a _ cell
postsynaptic cell
T OR F: a released neurotransmitter molecule carries a signal to a dendrite or the cell body of another neuron or to the cells of an effector organ
true
_c cells are in charge of releasing neurotransmitter from their neuron’s axon terminal
presynaptic cells
Axons range in length from 1 _ to 1 m
1 mm
In order for an axon terminal to carry out its function, it must have:
_ for synthesizing neurotransmitters
transporter molecules to move NTs
substrates across membranes
vesicles to store NTs until an action potential triggers exocytosis
enzymes for synthesizing NTs
Vesicles store NTs until an action potential triggers _
exocytosis
_ _n is too slow to complete the process of transport from cell body to axon terminal
simple diffusion
Simple diffusion is too slow to complete the process of transport from cell body to axon terminal, therefore special transport mechanisms exist for _ transport
axonal transport
Neurons move products from the cell body to axon terminal, a.k.a. _e transport
anterograde
Neurons move products from the axon terminal to the cell body using _e transport
retrograde
_ axonal transport and _ axonal transport are both used for anterograde and retrograde transport.
Fast axonal transport and slow axonal transport
T or F: only fast axonal transport involves proteins, including microtubules and a variety of neurofilaments
false - both fast and slow axonal transport involves proteins
Slow axonal transport (0.5 - _ mm/day) is generally associated with movement of small soluble molecules in the cytosol
0.5 - 44 mm/day (up to the length of a fingernail)
Fast axonal transport (100 - _ mm/day) is associated with movement of vesicles, including synaptic vesicles
400 mm/day (up to the length of a hand?)
Fast axonal transport of vesicles uses _ to extend the length of the axon and function as “tracks” for transport molecules
microtubules
Proteins that essentially “walk” down the microtubules, carrying a vesicle with them, run on tracks called _
kinesins
Fast axonal transport of vesicles requires _ for energy
ATP
Most ion channels are _ because different regions of a neuron generally have specialized functions
gated channels
The opening or closing of ion channels changes the … for a specific ion, resulting in a change in the electrical properties of the cell or the release of a NT
permeability of the plasma membrane
Nongated channels or _ channels are found in the plasma membrane
leak channels
Nongated channels or leak channels are found in the plasma membrane, and are responsible for the _ membrane potential
resting membrane potential
- channels open or close in response to the binding of a chemical to a specific receptor in the plasma membrane
ligand-gated
In neurons, ligand-gated channels are most densely located in the _ and cell body - areas that receive communication from presynaptic neurons in the form of NTs
dendrites
- channels open or close in response to changes in membrane potential
voltage-gated
_-gated potassium and -gated sodium channels are located throughout the neuron, but are more densely clustered in the axon and are present in greatest density in the axon hillock
Voltage-gated sodium and voltage-gated potassium channels
When voltage-gated _ channels are open, _ enters the cytosol of the axon terminals and triggers the release of NT
voltage-gated calcium channels; calcium
Neurons can be classified structurally according to the number of _ that project from the cell body
processes (i.e., axons and dendrites)
_ neurons are generally sensory neurons with two projects: an axon and a dendrite coming off the cell body
bipolar
the two senses that use bipolar neurons are _ and vision
smell / olfaction
Pseudo-unipolar neurons are named as such because the _ is modified to function much like an axon, and is a functional continuation of the axon
dendrite
Pseudo-unipolar neurons are named as such because the dendrite is modified to function much like an axon, and is a functional continuation of the axon. This modified dendritic process is called the _ axon, because it originals in the exterior with sensory receptors and functions as an axon in that it transmits action potentials
peripheral axon
_r neurons are the most common neurons
multipolar neurons
The cell body and dendrites of efferent neurons are located in the CNS, except for the _ic _ic neurons
autonomic postganglionic neurons
The axon leaves the CNS and becomes part of the _ NS as it travels to the effector organ it innervates
peripheral / PNS
Most _t neurons are pseudo-unipolar neurons, with the cell body located outside the CNS in a ganglion
afferent neurons
_neurons account for 99% of all neurons in the body
interneurons
Interneurons account for 99% of all neurons in the body, entirely in the _NS
central nervous system
Interneurons perform all the functions of the CNS, including:
processing sensory info from afferent neurons
creating and sending out commands to effector organs through efferent neurons
and carrying out…
complex functions of the brain such as thought, memory and emotions
Cell bodies of neurons are often grouped into _
nuclei
Axons travel together in bundles called _ways, _ts, or _ures
pathways, tracts, or commissures
In the PNS, cell bodies of neurons are clustered together in _, and the axons travel together in bundles/nerves
ganglia
Glial cells’ main functions include:
providing structural integrity to the NS
chemical and anatomical support that permits…
neurons to carry out their functions
There are four types of glial cells:
astrocytes
microglia
_
Schwann cells
oligodendrocytes
T OR F: of glial cells, only oligodendrocytes are located in the PNS
FALSE - only Schwann cells are found in the PNS
Neurolemmocytes are another name for _ cells
Schwann, found in the PNS
The primary function of oligodendrocytes (CNS) and Schwann cells (PNS) is to form…
myelin around the axons of neurons
Myelin provides insulation that enables neurons to … more efficiently and rapidly
transmit action potentials
Myelin consists of _ layers of the plasma membranes of either oligodendrocytes or Schwann cells
concentric
T OR F: Oligodendrocytes send out projections providing the myelin segment for one axon each, whereas Schwann cells form myelin provides for several axons each
false - oligodendrocytes provide for many axons, whereas Schwann cells provide myelin for one axon each
T or F: many oligodendrocytes or Schwann cells are needed to provide the myelin for a single axon
true
The lipid bilayer of a plasma membrane has _ permeability to ions, the several layers of membrane that make up a myelin sheath substantially _ leakage of ions across the cell membrane
low permeability = less leakage/chance of the suckers getting out; reduces leakage
_ of _ are the gaps within myelin
Nodes of Ranvier
The axonal membrane that contains voltage-gated sodium and potassium channels that function in the transmission of action potentials by allowing ion movement across the membrane are due to the gaps within the myelin, known as _ _ _
Nodes of Ranvier
All cells in the body have a negative resting membrane potential, ranging from -5 mV to -_mV
-100!
The chemical forces for moving Na and K ions across the plasma membrane and the differences in the permeability of the plasma membrane to these ions, establish the _ _ _
resting membrane potential
Sodium ions are at a higher concentration _ the cell and are balanced electrically by the presence of chloride ions outside the cell
outside the cell
_ ions are at a higher concentration inside the cell and are balanced electrically by the presence of organic anions, primarily proteins, inside the cell
potassium ions
As potassium ions move, they carry their positive charge _ the cell, which leaves the _ [opposite] of the cell negatively charged relative to the _ [first answer], creating a negative membrane potential
outside the cell
inside
outside
Currents are typically expressed in units of _ (10 ^ -6 amperes)
microamps
The greater the electrical potential, the greater the _ for ion movement
force
T OR F: the presence of a force necessitates ion movement
false - it can depend on resistance or conductance (its opposite)
The ICF and ECF have high resistance to current flow because their fluids are rich in ions. T or F?
false - the ICF and ECF have LOW resistance to current flow
(R) is a measurement of the hindance to charge movement
resistance
(g) is the ability of an ion to cross a plasma membrane depending on the permeability of the plasma membrane to that ion
conductance
_’s law suggests that the conductance of a particular ion increases as the membrane’s permeability to that ion increases:
l = E / R
Ohm’s law
Cells permeable to potassium only would see K+ move out of the cell because of a _ force
chemical force
Cells permeable to potassium only would see K+ move out of the cell because of a chemical force. As some leave the cell, the inside of the cell becomes _ charged relative to the outside, creating an electrical force that moves potassium ions into the cell, opposing the chemical force
negatively charged
Cells permeable to potassium only would see K+ move out of the cell. Eventually enough potassium leaves the cell that the electrical force becomes strong enough to oppose further movement of K+ ions out of the cell because of chemical force, resulting in…
no net movement of potassium ions
Cells permeable to K+ cells only have a potassium equilibrium potential of approximately -_mV in neurons
-94 mV
At potassium equilibrium potential, the electrical force exactly opposes chemical force, meaning…
no potassium moves
Ek refers to…
equilibrium potential for potassium
Ex refers to equilibrium potential of…
any ion (i.e., x = anything)
For a cell permeable only to Na+, the electrical force tends to take sodium… because of the repulsion between the positively charged sodium ions and the net positive charge inside the cell
out of the cell
The number of open _ channels far exceeds the number of open _ channels for ion gradients across the cell membrane
more open potassium channels to open sodium channels
T or F: sodium and potassium come to equilibrium because the movement of each opposed the other
false - sodium and potassium CANNOT come to equilibrium because the movement of each opposes the other
The resting membrane potential is actually much closer to the potassium equilibrium potential than the sodium one because…
the cell is more permeable to potassium, i.e., more potassium leaves the cell than sodium enters
NOTE: this differs from action potentials, with 3 Na+ released to 2 K+ entering the cell. Perhaps a way to balance out the permeability
If a neuron had equal permeability to sodium and potassium ions, would the resting membrane potential of that cell be more negative or less negative than -70 mV?
the membrane potential would be less negative (more depolarized), to balance the more reduced concentration of positive K+ ions
The sodium-potassium pump establishes the concentration gradients and maintains them. T or F?
true
Because the sodium-potassium pump is _ - it transports a net positive charge out of the cell - it contributes directly to the resting membrane potential, despite a minimal effect that accounts for only a few millivolts of charge separation
electrogenic
Because energy is required to sustain the resting state of a neuron, the cell is not at equilibrium; rather, it is in a _ _
steady state
The membrane potential depends on the _ _ of the membrane to the different ions that exist on either side
relative permeabilities of the membrane to different ions
As the membrane’s permeability to a particular ion increases, the membrane potential moves _ to that ion’s equilibrium potential
closer
Can the Nernst equation be used to calculate the membrane potential of an ion?
no, just the EQUILIBRIUM potential for a specific ion - we use the GHK equation instead
The GHK equation, or --_ equation, the membrane potential can be approximated for situations in which only sodium and potassium are permeant
Goldman-Hodgkin-Katz equation
“o” and “i” respectively refer to the _ outside and inside the cell for the GHK equation
concentration outside and inside the cell, respectively
“P Na” and “P K” are the _’s _ to sodium and potassium, respectively, in the GHK equation
membrane’s permeability for sodium and potassium
By dividing the GHK equation’s numerator and denominator both by “P K”, we can calculate the membrane potential in _
millivolts
If the permeability to either sodium or potassium is equal to zero (i.e., equilibrium potential for the ion that is not zero), then the GHK equation becomes…
the Nernst equation for the other ion
If the membrane is permeable to only one ion, then the membrane potential is…
equal to the equilibrium potential of that ion
The net electrochemical force on an ion tends to move that ion across the membrane in the direction that…
will move the membrane potential toward that ion’s equilibrium potential
If sodium is 130 mV away from equilibrium (at a resting membrane potential of -70) whereas potassium is only 24 mV away from equilibrium, the electrochemical force moving sodium into the cell is _ than the electrochemical force moving potassium out of the cell
greater
- the further away from an ion’s equilibrium potential, the greater the electrochemical force working against it
I Na = g Na (Vm - E Na) is…
the sodium current
I Na = g Na (Vm - E Na) shows…
I = current of a specific ion
g equals the _ of that ion (directly related to permeability)
E equals equilibrium potential of that ion and
Vm equals membrane potential
g equals the conductance of that ion (opposite of resistance to flow)
The channels responsible for the resting membrane potential are _ channels
leak
T OR F: neurons have gated ions and leak channels
true
If sodium ion channels open, then sodium movement _ the cell increases, driving the membrane potential toward the sodium equilibrium potential
INTO the cell
Many toxins exert their poisonous effects by interfering with the actions of _ _
ion channels
Hyperpolarization moves the mV to _ than -70 mV
LOWER - becomes -80, -90, etc., i.e., more polarized
_ moves the mV to higher than -70 mV, i.e., -60, 0, etc.
depolarization, i.e., less polarized
Repolarization moves the mV…
back to its resting potential, i.e., to below zero and eventually to -70 mV
Tetrodotoxin, a neurotoxin from blowfish, attacks nervous system function by blocking - _ channels necessary for producing an action potential
voltage-gated sodium channels
_ potentials are small electrical signals that act over short ranges because they diminish in size with distance
graded potentials
T or F: action potentials are large signals capable of traveling long distances without decreasing in size
true
Stimuli that produce graded potentials are:
chemical stimuli and
_ stimuli
sensory stimuli, such as a touch or light
Chemical stimuli that produces graded potentials for neurotransmitters includes the …on a dendrite or the cell body of a neuron
BINDING TO RECEPTORS on a dendrite or the cell body of a neuron
Sensory receptors at the peripheral ending of an _ neuron provide stimuli that produces graded potentials
afferent
The _ of the change in membrane potential varies with according to the strength of the stimulus
magnitude
The spread of voltage by passive charge movement is called _ conduction
electrotonic conduction
As the graded potential spreads from the site of the stimulation, the current is spread over a larger area, and some current leaks across the plasma membrane. As a result, the size of the membrane potential change _ as it moves from the site of initial stimulation
decreases
T or F: graded potentials are only depolarizations
false - they can be de- or hyper-polarizations
Graded potentials determine whether a cell…
will generate an action potential
If one type of neurotransmitter binding to its receptors caused sodium channels to open, then sodium ions would move _ the cell and the resulting graded potential would be a depolarization
INTO THE CELL
If another type of neurotransmitter binding to its receptors caused potassium channels to open, then potassium ions would move _ of the cell, and the resulting graded potential would be a hyperpolarization
OUT OF THE CELL
A _ is a critical value of membrane potential that must be exceeded if an action potential is to be generated
threshold
Graded potentials that are depolarizations are described as _tory, whereas graded potentials that are hyperpolarizations are considered _tory
depolarizations are excitatory (they go up - less polar) whereas hyperpolarizations are inhibitory (they go down - more polar)
Inhibitory graded potentials take the membrane potential … the threshold to elicit an action potential
away from the threshold
Excitatory graded potentials take the membrane potential … the threshold to elicit an action potential
closer to the threshold
T or F: a single graded potential is generally not of sufficient strength to elicit an action potential
true
T or F: temporal summation is the overlap in time of action potentials that can sum, both temporally and spatially
false - it is the overlap in time of GRADED potentials
_ summation is defined as the effects of stimuli from different sources occurring close together in time summation
spatial summation
In spatial summation, a hyperpolarizing graded potential and a depolarization graded potential tend to…
cancel each other out
A _ of charge is said to exist across the membrane, enabling potential energy to exist
separation
Cations are attracted by the _ charge inside the cell and have an inward-directed electrical driving force
negative charge inside the cell
If potassium moved into the cell, it would bring its positive charge with it, thereby making the membrane _ negative and taking potassium further from equilibrium
less negative (Ek = -94 mV)
The _ driving force for an uncharged solute to move into a cell is determined by the …equation
van’t Hoff equation
‘triangle’ G = RT ln [S]i / [S]o is the …equation
van’t Hoff equation
[S]o in the van’t Hoff equation is the _ of solute S outside the cell, and [S]I is the _ of solute S inside the cell
concentration
‘triangle G’ = RT ln [l]i / [l]o + zFE is the van’t Hoff equation for determining the _ driving force for an ion (l) to move INTO the cell
electrochemical driving force for an ion
‘triangle G’ = RT ln [l]i / [l]o + zFE is the van’t Hoff equation for determining the electrochemical driving force for an ion (l) to move into the cell
G = …
R = universal gas constant (0.082 litrre-atm/mole-K)
T = absolute temperature (K)
z = valence of the ion
E is the membrane potential
F is Faraday’s constant for electrical forces (9.65 x 10^4 joules/volt-mole)
G = free energy
The Nernst equation gives the value of the equilibrium potential in millivolts and assumes that the temperature is at or near …
body temperature, i.e., 37 degrees Celsius
The sign (direction) of the equilibrium potential depends solely on the direction of the…
concentration gradient
this is noticeable in the Nernst equation, with a valence of +1 meaning it is a larger concentration gradient and requires a larger membrane potential to balance it (most commonly, K+ gradient larger than Na+)
A valence of +1 in the Nernst equation means that it is a _ concentration gradient and requires a _ membrane potential to balance it
larger concentration gradient, and requires a larger membrane potential to balance it
e.g., (most commonly, K+ gradient larger than Na+)
If concentration gradients are equal, then the equilibrium potential is…
zero
ie., Co / Ci = 1, making the equilibrium potential (log of 1) zero
When ions are transported passively, they move _ their electrochemical gradient
down
Are both actions of ion movement for the sodium-potassium pump active?
yes, they both move up their electrochemical gradient
Each neuron can access upwards of _ synapses
10
The PNS is not protected by skull or the vertebrae. T or F?
T
Brain damage is more often the result of _NS damage since it is less protected than the CNS
pNS DAMAGE, rather than CNS damage
The synaptic cleft is about _ um long
200
Myelinated structures look _, therefore are called _ matter
white; white
Grey matter is particular to collection of nerve cell _
bodies
The cell body works as a _tor
capacitor (a great insulator)
A piece of biological tissue is a good conductor of electricity. T or F?
false - imagine Homer’s image fading, whereas copper wires are great conductors, maximizing conduction
Myelination is considered increasing _ _
increasing membrane resistance
Oligodendrocytes look like _
octopi, myelinating multiple CNS axons
There are roughly _ to _ layers of myelin, maximizing conduction velocity and reducing signal loss
50 to 100 layers per neuron
The exposure of the Node of Ranvier is where the …
action potential is generating along the axon
The speed of axon generation is from _ to _ m/s
2 vs 80 m/s
Damage of the myelin sheath is specific to patients with _ _, leading to slowing down or even blockage between one’s brain and their body. (brain and spinal cord)
multiple sclerosis
Symptoms of MS are:
visual disturbances
muscle weakness
trouble with coordination, balance
_
thinking and memory problems
sensations with prickling, numbness, pins and needles
How is MS treated?
by reducing leakage occurrence by blocking calcium channels
_ are the ligand for ligand-gated channels, largely found by the dendrites
neurotransmitters
Voltage-gated channels act like _ in a computer
transistors
The Nernst equation can only be used if…
only 1 ion is permeable across the membrane
When a neuron is at rest, it is most permeable to _
potassium
Sodium is permeable 35 times _ than potassium along the membrane
less than potassium, therefore resting membrane potential is closer to potassium equilibrium potential than the sodium one
For Na+, the electrical force is into the cell, the chemical force is also into the cell. The netforce is +60mV: Na+ flows into the cell but the membrane has…which prevents it from doing it as much as it wants
low permeability to Na+
Why is the electrical force and chemical force for Na+ at resting membrane potential both into the cell?
the chemical force is strong to go into the cell, and the electrical force (-70 mv) compels Na+ to also go in the cell
Transmission of electrical signal exists through the _ membrane
biological
_d stimuli are graded potentials not strong enough to inspire an action potential
subthreshold
_ stimuli in a graded potential generates an action potential
threshold stimuli
Threshold is mapped with y-axis as membrane potential (mV) vs. x-axis as _
time (msec)
Temporal summation can be visualized as…
telegraph (one stimulus repeated)
Spatial summation can be visualized as….
multiple people talking at once
Do temporal and spatial summation happen together in nature?
yes, for the most part. it is rare that only one of them exists at a time
_ _s record the value of a membrane potential
intracellular electrodes
What happens during depolarization in an action potential?
a. sodium rushes out and the membrane potential becomes negative
b. sodium rushes in and the membrane potential becomes positive
c. potassium rushes in and the membrane potential becomes positive
d. potassium rushes in and the membrane potential becomes negative
b. sodium rushes in and the membrane potential becomes positive
During repolarization in an action potential, what happens to the membrane permeability of sodium (Na+) and potassium (K+)?
a. permeability of K+ and Na+ increases
b. permeability of K+ and Na+ decreases
c. Permeability of K+ increases and permeability of Na+ decreases
d. Permeability of K+ decreases and permeability of Na+ increases
c. Permeability of K+ increases and permeability of Na+ decreases
An action potential travels all the way down an axon. Where does a graded potential travel?
a. all the way down an axon as well
b. dendrites, cell body, and sensory receptors
c. synapse, hillocks, and terminals
d. nowhere; graded potentials do not travel
b. dendrites, cell body, and sensory receptors
An action potential either fires or not (all-or-none), and it maintains its strength as it travels. How does a graded potential compare?
a. It is all-or-none, and it maintains its strength as it travels.
b. It is weak, depending on the stimulus strength, but maintains its strength as it travels.
c. It is all-or-none, but it weakens as it travels.
d. It is weak, depending on the stimulus strength, and dissipates away from the stimulus.
d. It is weak, depending on the stimulus strength, and dissipates away from the stimulus.
Action potentials use voltage-gated channels. Which type of channels are involved in producing a change in the membrane voltage in graded potentials?
a. voltage-gated only
b. ligand-gated and mechanically gated
c. mechanically gated only
d. ligand-gated only
b. ligand-gated and mechanically gated
What is the difference between excitatory postsynaptic potentials (EPSPs) and inhibitory postsynaptic potentials (IPSPs)?
a. IPSPs depolarize the cell and EPSPs hyperpolarize the cell.
b. EPSPs are all-or-none and IPSPs are graded
c. EPSPs depolarize the cell and IPSPs hyperpolarize the cell
d. EPSPs are fast and IPSPs are slow.
c. EPSPs depolarize the cell and IPSPs hyperpolarize the cell
What is a difference between temporal and spatial summation?
a. In temporal summation, ionotropic responses are critica
b. In spatial summation, the postsynaptic potentials happen at the same time.
c. In spatial summation, metabotropic responses are critical.
d. In temporal summation, the postsynaptic potentials happen at the same time.
b. In spatial summation, the postsynaptic potentials happen at the same time.
