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SP 4B-RG: Neural Communication
SP 4B-RG: Neural Communication Notecards
121
Physiology
Undergraduate 3
10/07/2012
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Term
__________ and __________ are excitable tissues.
 Definition
1) Nerve
2) Muscle
Term
What tissues are excitable?
 Definition
1) Nerve
2) Muscle
Term
Nerve and muscle tissues are able to:
-Undergo rapid changes in their membrane __________
-Changer their __________ __________ into __________ __________.
 Definition
1) Membrane potentials
2) Resting potentials
3) Electrical signals
Term
__________ __________ are critical to the function of the nervous system and all muscles.
 Definition
1) Electrical signals
Term
Electrical signals are critical to the function of what?
 Definition
1) The nervous system
2) All muscles
Term
Neurons communicate by means of an electrical signal called the __________ __________.
 Definition
1) Action potential
Term
How do neurons communicate?
 Definition
1) Through action potentials
Term
__________ __________ are based on movements of ions between the outside and inside of a cell.
 Definition
1) Action potentials
Term
What are action potentials based off of?
 Definition
1) The movements of ions between the outside and inside of the cell
Term
When an action potential occurs what is sent to neighboring neurons?
 Definition
1) Molecular message
Term
True or False: The nerve pathways in neurons are continuous "wires"
 Definition
1) FALSE: Neuron nerve pathways are NOT continuous "wires" but a series of separate cells
Term
Neuronal communication is based on mechanisms for producing __________ __________ and __________.
 Definition
1) Electrical potentials
2) Currents
Term
What is neuronal communication based on?
 Definition
1) Electrical potentials
2) Currents
Term
__________ __________ is the difference in concentration of charged particles between different parts of the cell.
 Definition
1) Electrical potential
Term
What is electrical potential?
 Definition
1) The difference in concentration of charged particles between the different parts of the cell
Term
__________ __________ is flow of charged particles from one point to another within the cell.
 Definition
1) Electrical current
Term
What is electrical current?
 Definition
1) The flow of charged particles from one point to another within the cell
Term
True or False: Living cells are polarized.
 Definition
1) TRUE
Term
The resting membrane potential is __________ with more negatively charged particles on the __________ of the membrane.
 Definition
1) -70mV
2) Inside
Term
What ions are concentrated outside of the cell? Within the cell?
 Definition
Inside:
1A) K+ - Low
1B) Na+ - High
1C) Cl- - High
Outside
2A) K+ - High
2B) Na+ - Low
2C) Cl- - Low
2D) A- - High
Term
Membrane potential is often abbreviated as __________.
 Definition
1) mV
Term
A negative sign often means an excess of __________ in the __________.
 Definition
1) Anions
2) ICF
Term
Historically, the giant axons of __________ which are __________ in diameter, were used to observe local changes in membrane potential.
 Definition
1) Squid
2) 1mm
Term
__________ __________ is voltage across the plasma membrane of most cells due to imbalance between positive and negative charge. The result is ions diffusing through selective membrane channels.
 Definition
1) Membrane potential
Term
What is membrane potential? What is the result of membrane potential?
 Definition
1) Membrane potential is voltage across the plasma membrane of most cells due to an imbalance between positive and negative charge.
2) The result is ions diffusing through selective membrane channels
Term
__________ __________ __________ is the membrane voltage at which electrical force of an ion is equal and opposite to the chemical force.
 Definition
1) Nernst equilibrium potential
Term
What is Nernst equilibrium potential?
 Definition
The membrane voltage at which electrical force on an ion is equal and opposite to the chemical force
Term
The __________ __________ __________ __________ __________ is the voltage at which the current carried by all permeable ions adds up to zero. Energy is required in the long term to maintain differential concentrations of ions in ICF and ECF
 Definition
1) Steady state resting membrane potential
Term
What is the steady state resting membrane potential?
 Definition
1) Voltage at which the current carried by all permeable ions adds up to zero
Term
An __________ __________ is a rapid fluctuation in membrane potential involved in long distance signaling within neurons and muscle cells
 Definition
1) Action potentials
Term
__________ is a decrease in potential; membrane less negative.
 Definition
1) Depolarization
Term
What is depolarization? What occurs to the membrane?
 Definition
1) Decrease in potential
2) Less negative
Term
__________ is the return to resting potential after depolarization.
 Definition
1) Repolarization
Term
What is repolarization?
 Definition
1) The return to resting potential after depolarization
Term
__________ is an increase in potential; membrane more negative.
 Definition
1) Hyperpolarization
Term
What is hyperpolarization? What occurs to the membrane?
 Definition
1) Increase in potential
2) More negative
Term
At rest the inside of a cell is __________.
 Definition
1) -70 mV (milivolts)
Term
What occurs with constant inputs to dendrites?
 Definition
1) Inside of the membrane becomes more positive
Term
If resting potential rises above __________ an __________ __________ starts to travel from the __________ __________ down the axon.
 Definition
1) Threshold
2) Action potential
3) Cell body
Term
What occurs if the resting potential rises above the threshold?
 Definition
1) An action potential starts to travel from the cell body down the axon
Term
The action potential opens the __________ __________ to allow __________ in.
When this occurs, the inside of the cell rapidly becomes more __________ than outside.
This __________ travels down the axon as leading edge of the action potential.
 Definition
1) Cell membrane
2) Na+
3) Positive
4) Depolarization
Term
What does the action potential open the cell membrane to allow in? What occurs to the cell when this happens?
 Definition
1) Na+
2) Cell rapidly becomes more positive than outside
Term
After depolarization __________ moves out of the cell restoring the inside to a __________ voltage.
This is called __________.
The rapid depolarization and repolarization produce a pattern called a __________ __________.
 Definition
1) K+
2) Negative
3) Repolarization
4) Spike discharge
Term
What occurs after depolarization? What does this do to the inside of the cell? What is this process called?
 Definition
1) K+ leaves the cell
2) Restores the inside to a negative voltage
3) Repolarization
Term
What is the rapid pattern of repolarization and depolarization called?
 Definition
1) Spike discharge
Term
Repolarization leads to a voltage below the __________ __________ called __________.
Now the neuron cannot produce a new __________ __________.
This is known as the __________ __________.
 Definition
1) Resting potential
2) Hyperpolarization
3) Action potential
4) Refractory period
Term
What occurs after repolarization? What is the stage called?
 Definition
1) After repolarization, a voltage drop below the resting potential (hyperpolarization) results in a neuron unable to produce an action potential
2) Stage is known as the refractory period
Term
A __________ __________ is created through the unequal distribution of ions and organic molecules across a cell membrane.
 Definition
1) Membrane potential
Term
How is a membrane potential created?
 Definition
1) Through the unequal distribution of ions and organic molecules
Term
What are the major cations / anions of the ICF? Of the ECF?
 Definition
1) ICF:
Cations: K+
Anions: Organic substances
2) ECF
Cations: Na+
Anions: Cl-
Term
How are membrane potentials created?
 Definition
1) Different ions in ICF vs. ECF
2) Diffusion through selective ion channels
3) Strong attractive forces between anions and cations
Term
What are the concentrations of major ions in the ECF and ICF?
 Definition
1) ECF:
Na+ - High
K+ - Low
Cl- - High
Organic anions - Low
2) ICF
Na+ - Low
K+ - High
Cl- - Low
Organic anions - High
Term
The __________ expresses electrochemical differences between IC and EC.
 Definition
1) Vm
Term
The resting membrane potential is __________ to __________; here, there is a very slight excess of negative charge on the __________ and a very slight excess of positive charge on the __________.
 Definition
1) 60mV - 95mV
2) Inside
3) Outside
Term
Membrane potential:
The plasma membrane is only permeable to __________.
The chemical force on K+ causes it to __________ down its concentration gradient.
An efflux of positive charge and an excess of unbalanced negative charge on the __________ of the plasma membrane generates Vm: an __________ force that opposes __________ force.
Consequently, an __________ __________ is created; this occurs when the electrical force balances the chemical concentration force.
 Definition
1) K+
2) Diffuse
3) Inside
4) Electrical
5) Chemical
6) Equilibrium potential
Term
Unequal electrolytes distribution between ECF and ICF causes what to occur?
 Definition
1) Diffusion of ions down their concentration gradients
2) Selective permeability of the plasma membrane
3) Electrical attraction of cations and anions
Term
Explain why the resting potential is at -70mV.
 Definition
1) The plasma membrane is very permeable to K+ (much leaks out)
2) There are many cytoplasmic anions that cannot escape due to size or charge (help to create negative charge)
3) Membrane much less permeable to Na+ (some leaks in)
4) Na+/K+ pump pumps out three Na+ for every two K+ brought in
-Requires great amount of ATP
-Needs glucose and oxygen to be supplied to nerve tissue
Term
The __________ __________ is determined by the unequal distribution of positive and negative charges across the membrane.
 Definition
1) Membrane potential
Term
How is the membrane potential determined?
 Definition
1) By the unequal distribution of positive and negative charges across the membrane
Term
What occurs when positive and negative charges are equally balanced on each side of the membrane?
When opposite charges are separated across the membrane?
 Definition
1) No membrane potential exists
2) Membrane potential exists
Term
Where do the unbalanced charges responsible for the potential accumulate?
 Definition
1) In a thin layer along opposite surfaces of the membrane
Term
True or False: The vast majority of the fluid in the ECF and ICF is negatively charged.
 Definition
1) FALSE: The vast majority of the fluid in the ECF and ICF is ELECTRICALLY NEUTRAL
Term
The greater the separation of charges across the membrane, the __________ the potential.
 Definition
1) Larger
Term
What occurs as the separation of charges across the membrane becomes larger and larger?
 Definition
1) The membrane potential becomes greater and greater
Term
__________ is ,ore concentrated outside of the cell (__________) and __________ is more concentrated inside of the cell (__________).
 Definition
1) Na+
2) ECF
3) K+
4) (ICF)
Term
Which cation / anion is more concentrated outside of the cell? Within the cell?
 Definition
1) Outside: Na+
2) Inside: K+
Term
The __________ __________ __________ results from the separation of charges across the cell membrane
 Definition
1) Resting membrane potential
Term
How does the resting membrane potential develop?
 Definition
1) From the separation of charges across the cell membrane
Term
What is the equation for membrane potential? What does each variable represent?
 Definition
1) Membrane potential:
Vm = Vin - Vout, where:
Vm - Membrane potential
Vin - Potential on the inside of the cell
Vout - Potential on the outside of the cell
Term
If we place some hypothetical salt AK on one side, what will occur?
 Definition
1) K+ will diffuse while A- will not
Term
The magnitude of the flux of an ion across a cell membrane is the product of its __________ __________ __________ and the __________ of the membrane to the ion.
 Definition
1) Electrochemical driving force
2) Conductance
Term
__________ __________ __________ is the sum of the electrical driving force and the chemical driving force due to the concentration gradient.
 Definition
1) Electrochemical driving force
Term
What is electrochemical driving force?
 Definition
1) The sum of the electrical driving force and the chemical driving force due to the concentration gradient
Term
At Ek, __________ chemical force on __________ is balanced by opposite electrical force.
 Definition
1) -90mV
2) K+
Term
What does the Nernst equation calculate?
 Definition
1) The equilibrium potential (E or V) for an ion
Term
The __________ __________ is the transmembrane potential at which no net ion movement occurs.
 Definition
1) Equilibrium potential
Term
What occurs when forces are acting on K+ at Ek?
 Definition
1) K+ efflux to establish equilibrium is very small
2) When Vm = Ek, net flux of K+ = 0
3) Equilibrium reached with small K+ concentration
Term
At ENa __________, chemical force on __________ is exactly balanced by opposite electrical force.
 Definition
1) +60mV
2) Na+
Term
A cell has relatively few resting __________ channels so at rest the conductance to __________ is quite low. Thus, despite the large chemical and electrical forces driving __________ into the cell, the influx is quite small.
In contrast, since there are many resting __________ channels, the membrane conductance of __________ is relatively large. As a result, the small net outward force acting on K+ at the __________ __________ __________ is enough to produce a __________ effux equal to the __________ influx.
 Definition
1) Na+
2) Na+
3) Na+
4) K+
5) K+
6) Resting membrane potential
7) K+
8) Na+
Term
What occurs when the membrane is impermeable to Na+?
 Definition
1) RMP = Ek
Term
For neurons RMP is __________.
 Definition
1) -70mV
Term
K+ is __________ times more permeable than Na+
 Definition
1) 25
Term
There is a steady state RMP when __________ efflux is balanced by an __________ influx.
 Definition
1) K+
2) Na+
Term
How does a steady state RMP occur?
 Definition
1) When a K+ efflux is equivalent to the Na+ influx
Term
A steady state occurs when Vm is closed to __________ than __________.
 Definition
1) Ek
2) ENa
Term
At -70mV, the net force on K+ is __________ but the permeability is __________.
Conversely, net force on Na+ is __________ but permeability is __________.
 Definition
1) Small
2) High
3) High
4) Low
Term
At -70mV, inward flux of __________ is offset by outward flux of __________.
 Definition
1) Na+
2) K+
Term
The __________ the concentration gradient, the __________ the equilibrium potential is for an ion.
 Definition
1) Greater
2) Larger
Term
If Vm = Eion, there is no __________ __________ and no __________ __________.
Cations:
If ICF is greater, Eion is __________
If ECF is greater, Eion is __________
Anions:
If ICF is greater, Eion is __________
If ECF is greaterm Eion is __________
 Definition
1) Net force
2) Net flux
3) Negative
4) Positive
5) Positive
6) Negative
Term
Vm is the result of __________ __________ through selective __________ __________ in the membrane.
If only one ion is permeable, Vm reaches the __________ __________ __________ for that ion: Eion
If more than one ion is permeable, Vm is closer to __________ for the most permeable ion.
 Definition
1) Ion diffusion
2) Ion channels
3) Nernst equilibrium potential
4) Eion
Term
What are a few examples of neuromodulators?
 Definition
1) Catecholamine
2) Dopamine
3) Norepinephrine
4) Epinephrine
5) Indolamine
6) Serotonin
Term
The __________ __________ is a complex network of neurons that form the rapid control system of the body.
 Definition
1) Nervous system
Term
__________ __________ of the nervous system include consciousness, intelligence, and emotion.
 Definition
1) Emergent properties
Term
The efferent neurons include __________ __________ __________ which control skeletal muscles, and __________ __________ which control smooth and cardiac muscles, glands, and some adipose tissue.
 Definition
1) Somatic motor neurons
2) Autonomic neurons
Term
Material is transported between the cell body and axon terminal by __________ __________.
 Definition
1) Axonal transport
Term
__________ __________ __________ that can develop into new neurons and glia are found in the ependymal layer as well as in other parts of the nervous system.
 Definition
1) Neural stem cells
Term
The __________ __________ describes the membrane potential of a cell that is permeable to only one ion.
 Definition
1) Nernst equation
Term
Membrane potential is influenced by the __________ __________ of ions across the membrane and by the __________ of the membrane to those ions.
 Definition
1) Membrane potential
Term
The permeability of a cell to ions changes when ion channels in the membrane __________ and __________.
 Definition
1) Open
2) Close
Term
Gated ion channels in neurons open or close in response to __________ or __________ signals or in response to __________ of the cell membrane; they also close to inactivation.
 Definition
1) Chemical
2) Mechanical
3) Depolarization
Term
The wave of depolarization that moves through a cell is known as __________ __________ __________.
 Definition
1) Local current flow
Term
Action potentials begin in the __________ __________ if a single graded potential or the sum of multiple graded potentials exceeds the __________ voltage.
 Definition
1) Trigger zone
2) Threshold
Term
__________ graded potentials make a neuron more likely to fire an action potential; __________ graded potentials make a neuron less likely to fir an action potential.
 Definition
1) Depolarizing
2) Hyperpolarizing
Term
The voltage-gated Na+ channels of the axon have a fast __________ __________ and a slower __________ __________.
 Definition
1) Activation gate
2) Inactivation gate
Term
During the __________ __________ __________, a higher-than-normal graded potential is required to trigger an action potential.
 Definition
1) Relative refractory period
Term
The myelin sheath around an axon speeds up conduction by increasing __________ __________ and decreasing current __________.
__________-diameter axons conduct action potentials faster than __________-diameter axons do.
 Definition
1) Membrane resistance
2) Leakage
3) Larger
4) Smaller
Term
The apparent jumping of action potential from node to node is called __________ __________.
 Definition
1) Saltatory conduction
Term
Changes in blood K+ concentration affect __________ membrane potential and the conduction of __________ __________.
 Definition
1) Resting
2) Action potentials
Term
In __________ __________ an electrical signal passes directly from the cytoplasm of one cell to another through gap junctions.
 Definition
1) Electrical synapses
Term
__________ __________ use neurotransmitters to carry information from one cell to the next, with the neurotransmitter diffusing across the __________ __________ to bind with receptors on target cells.
 Definition
1) Chemical synapses
2) Synaptic cleft
Term
Neurotransmitter receptors are either __________-__________ __________ __________ (ionotropic receptors) or __________ __________-__________ __________ (metabotropic receptors).
 Definition
1) Ligand-gated ion channels
2) Metabotropic receptors
Term
What are three ways in which neurotransmitter action is rapidly terminated?
 Definition
1) Reuptake into cells
2) Diffusion away from the synapse
3) Enzymatic breakdown
Term
When a presynaptic neuron synapses on a larger number of postsynaptic neurons, the pattern is known as __________.
 Definition
1) Divergence
Term
When several presynaptic neurons provide input to a smaller number of postsynaptic neurons, the pattern is known as __________.
 Definition
1) Convergence
Term
Synaptic transmission can be modified in response to activity at the synapse, a process known as __________ __________.
 Definition
1) Synaptic plasticity
Term
G protein-coupled receptors either create __________ __________ __________ or modify cell metabolism.
Ion channels create __________ __________ __________.
 Definition
1) Slow synaptic potentials
2) Fast synaptic potentials
Term
The summation of simultaneous graded potentials from different neurons is known as __________ __________.
 Definition
1) Spatial summation
Term
The summation of graded potentials that closely follow each other sequentially is called the __________ __________.
 Definition
1) Temporal summation
Term
__________ __________ of an axon terminal allows selective modulation of collaterals and their targets.
 Definition
1) Presynaptic modulation
Term
__________ __________ occurs when a modulatory neuron synapses on a postsynaptic cell body or dendrites.
 Definition
1) Postsynaptic modulation
Term
__________-__________ __________ and __________-__________ __________ are mechanisms by which neurons change the strength of their synaptic connections.
 Definition
1) Long-term potentiation
2) Long-term depression
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