Chapter 11: Functional Organization of Nervous Tissue
A depolarizing local potential will make the neuron ______ likely to generate a nerve impulse. more less
A
A molecule such as a neurotransmitter or a hormone that _____ is called a(n) ligand. binds to a receptor causes muscle contraction breaks down a neurotransmitter is released by a neuron
A
A specific molecule binds to a membrane receptor. This molecule is called a ______. ligand pump channel vesicle
A
An excitatory local potential will make the neuron ______ likely to generate a nerve impulse. more less
A
By definition, ______ occurs when multiple stimuli combine their effects on a cell to produce a response. summation inhibition potentiation
A
Electrically excitable cells use the difference of ______ across the cell membrane to carry out their functions. ions chemicals hormones proteins
A
Explain why the propagation of action potentials occurs in one direction. The absolute refractory period prevents the generation of an action potential in the reverse direction. Threshold prevents the generation of an action potential in the reverse direction. Myelin prevents the generation of an action potential in the reverse direction.
A
Gap junctions allow direct communication or ionic flow between adjacent cells for a(n) ______ synapse, while synapses that use neurotransmitters to signal from the presynaptic to postsynaptic cell are called _______ synapses. electrical, chemical direct, electrical chemical, electrical chemical, indirect
A
Inhibitory postsynaptic potentials involve ______ of the plasma membrane. hyperpolarization depolarization
A
Large, negatively charged proteins inside the cell _____ readily diffuse across the neuron membrane. cannot can
A
Potassium has a much higher concentration in the _____ fluid than in the _____ fluid. intracellular, extracellular extracellular, intracellular
A
Potassium ions and negatively charged proteins are more concentrated ______ the cell. inside outside
A
Presynaptic inhibition ______ the amount of neurotransmitter released from the presynaptic terminal. reduces increases
A
Summation that results from a single synapse firing rapidly in sequence is called ______ summation. temporal spatial
A
The electrical signals that are propagated along axons, regulating and coordinating body activities, are known as _____. action potentials neurotransmitters graded potentials
A
The function of acetylcholinesterase is to ______. break down the neurotransmitter acetylcholine bind to acetylcholine on the post-synaptic terminal catalyze the formation of acetylcholine
A
The neuron plasma membrane is 50-100 times more permeable to _____ than to sodium. potassium chloride calcium
A
The plasma membrane is more permeable to _____ and chloride and much less permeable to _____. potassium, sodium sodium, potassium
A
The role of the Na+-K+ pump in membrane potential regulation is that it ______. reestablishes correct ion distribution, compensating for ion leakage regulates the opening and closing of Na+ and K+ channels moves Na+ in and K+ out, along their concentration gradients
A
The second neuron at a synapse (where the neurotransmitter binds) would be the _____ neuron. postsynaptic secondary presynaptic aftersynaptic
A
The sodium-potassium pump is responsible for what portion of the resting membrane potential? Less than 15mV Over 60mV No portion of the resting membrane potential About half of the resting membrane potential
A
The sodium-potassium pump plays a _____ role in maintaining resting membrane potential. minor major
A
The type of action potential conduction in an unmyelinated axon is ______ conduction. continuous local saltatory depolarization
A
What moves in a local current? Positively charged ions Uncharged molecules
A
When the resting membrane potential becomes more _____ the condition is referred to as hyperpolarization. negative positive
A
_____ occurs when the inside of the plasma membrane becomes more negative, and ______ occurs when the inside of the plasma membrane becomes less negative. Hyperpolarization, depolarization Depolarization, repolarization Depolarization, hyperpolarization
A
______ is the electrolyte that has the greatest influence on resting membrane potential due to the greater permeability of the plasma membrane to this electrolyte. Potassium Sodium
A
Identify the characteristics that play a role in the electrical signals created by nervous tissue. Select all that apply. Semipermeable membranes help create a separation of ions. Electrical charges are separated across the cell membrane. Specific channels alter membrane permeability to ions. Voltage is generated by an intracellular mechanism that accumulates electrons.
A B C
Identify the characteristics that play a role in the electrical signals created by nervous tissue. Select all that apply. Specific channels alter membrane permeability to ions. Semipermeable membranes help create a separation of ions. Electrical charges are separated across the cell membrane. Voltage is generated by an intracellular mechanism that accumulates electrons.
A B C
Identify the statements that are true regarding the nature of the large proteins found within neurons. Select all that apply. They are synthesized inside the cell. They are negatively charged. They do not readily diffuse through the membrane. They act as receptors to neurotransmitters.
A B C
Graded potentials may be caused by ______. Select all that apply. mechanical stimulation chemical signals binding to receptors changes in voltage across the plasma membrane spontaneous changes (not caused by a specific stimulus) an increase in the activity of the sodium - potassium pump temperature changes
A B C D F
As a result of nervous tissue possessing electrical properties along the membrane, which characteristics are present? Select all that apply. The ability to generate graded potentials The ability to have a refractory period in which the cell is insensitive to stimulation The ability to create a relatively stable resting membrane voltage The ability to propagate multiple signals of varying strength and magnitude along the axon The ability to generate action potentials
A B C E
Gated ion channels respond to which of the following stimuli? Select all that apply. Voltage changes Mechanical stimulus Temperature changes They are always open. Ligands binding to receptors
A B C E
Identify the ions that have a higher concentration in the extracellular fluid compared to the intracellular fluid. Select all that apply. Na+ Cl- K+ Ca++
A B D
Ligand-gated ion channels allow which of the following to pass through the plasma membrane? Select all that apply. Na+ K+ HCO3- proteins Ca++ Cl-
A B E F
Identify the characteristics of action potentials. Select all that apply. They are all-or-none. The strength of the stimulus determines the magnitude of the action potential. The strength of the stimulus determines the frequency of the action potentials. Multiple stimuli can create larger action potentials, and fewer stimuli can create smaller action potentials. They are propagated in a non-decremental fashion.
A C E
Describe characteristics of receptors at the synapses. Select all that apply. Only specific molecules are able to bind to the receptors They only open in response to voltage changes across the membrane All receptors are gated ion channels They are ligand activated receptors
A D
A depolarizing local potential will make the neuron ______ likely to generate a nerve impulse. less more
B
A partial depolarization of a postsynaptic neuron or muscle cell in response to a neurotransmitter is a(n) ______ postsynaptic potential. negative excitatory positive inhibitory
B
Action potentials are conducted more rapidly along ______ axons. myelinated unmyelinated
B
Action potentials are conducted more rapidly along an axon with a _____ diameter. smaller larger
B
Action potentials are conducted more rapidly when the myelin sheath is _____. thinner thicker
B
An IPSP causes an ______ on its target membrane excitatory postsynaptic potential inhibitory postsynaptic potential
B
An axon with a thicker myelin sheath will conduct action potentials ______ than an axon with a thin myelin sheath. slower faster
B
An unmyelinated axon will conduct action potentials more ______ than a myelinated axon. quickly slowly
B
As neurotransmitter molecules diffuse away from the synaptic cleft, the amount of time the remaining molecules remain bound to the receptors ______. remains the same decreases increases
B
At a synapse, the neuron that releases a neurotransmitter referred to as ______. adrenergic presynaptic postsynaptic ganglionic
B
At a synapse, the neuron that responds to the neurotransmitter is the ______ neuron. presynaptic postsynaptic
B
Decremental means that the strength of the signal _____ as it gets farther from the source. stays the same decreases increases
B
Entry of ______ ions into the synaptic knob triggers exocytosis of neurotransmitters. sodium calcium potassium chloride
B
Explain why Na+ ions diffuse into the neuron when the Na+ channels open. Because K+ moves out of the cell, the positive charges repel Na+, forcing Na+ ions to enter the cell. Na+ is more concentrated outside the cell than inside; hence, the concentration gradient causes diffusion into the cell. The Na+ channel acts like a pump to actively move Na+ into the cell when the channels open. The Na+/K+ pump moves the Na+ into the cell when the Na+ channels open. Confidence Level
B
Identify the statement that best describes the characteristics of a voltage-gated ion channel. When a voltage change occurs on the plasma membrane, these channels are able to have ligands bind to them to cause them to open. They open and close in response to a specific voltage change across the plasma membrane. ATP causes these channels to open and force ions in and out of the cell, which creates a voltage on the plasma membrane. The binding of a ligand to these channels causes a voltage change to occur on the cell's plasma membrane.
B
Identify the type of synapse that includes a presynaptic cell, synaptic cleft, and postsynaptic cell. Neurotransmitter Chemical Direct Electrical
B
Identify why the membrane becomes hyperpolarized following the repolarization phase of an action potential. Voltage-gated Na+ channels remain open for a short period of time after reaching RMP; allowing Na+ to diffuse into the cell. Voltage-gated K+ channels remain open for a short period of time after reaching RMP; allowing K+ to diffuse out of the cell. Voltage-gated K+ channels remain open for short period of time after reaching RMP; allowing K+ to diffuse into the cell. Voltage-gated Na+ channels remain open for a short period of time after reaching RMP; allowing Na+ to diffuse out of the cell.
B
Identify why the membrane becomes hyperpolarized following the repolarization phase of an action potential. Voltage-gated Na+ channels remain open for a short period of time after reaching RMP; allowing Na+ to diffuse out of the cell. Voltage-gated K+ channels remain open for a short period of time after reaching RMP; allowing K+ to diffuse out of the cell. Voltage-gated Na+ channels remain open for a short period of time after reaching RMP; allowing Na+ to diffuse into the cell. Voltage-gated K+ channels remain open for short period of time after reaching RMP; allowing K+ to diffuse into the cell.
B
If the area just inside the membrane of a cell is more negative than the outside, the resting membrane potential will have a ______ value. positive negative
B
Once stimulated, a single action potential ______. travels long distance along the entire plasma membrane travels only a short distance before stimulating another action potential stops once it passes the axonal hillock
B
Synapses in which neurotransmitters are released are called ______ synapses. electrical chemical
B
The entry of calcium into the synaptic knob triggers ______. production of neurotransmitter exocytosis of neurotransmitter opening of sodium gates the development of a local potential
B
The nervous system transfers information from one part of the body to another by using _____. nervous potentials action potentials local potentials
B
The plasma membrane is more permeable to _____ and chloride and much less permeable to _____. sodium, potassium potassium, sodium
B
The purpose of the absolute refractory period is to _____. decrease the speed of the propagation of action potentials prevent action potentials from being generated in reverse direction increase the speed of the propagation of action potentials prevent action potentials from being generated in the forward direction
B
The term "potential difference" refers to the ______. possible difference of ion flow through channels in the plasma membrane difference in electrical charge across the plasma membrane movement of ions across the plasma membrane of a neuron arrangement of Na+ ions outside the cell and the K+ ions inside the cell
B
Toward the end of the repolarization phase, the ______ gates of the sodium channel close and the ______ gates of the sodium channels open. inactivation, activation activation, inactivation
B
What is the name of the gaps found between segments of myelin along an axon? Initial segments Nodes of Ranvier Synapses Internodes
B
What is the nature of the signal that propagates along neurons that ultimately regulates and coordinates the functions of the body? It is hormonal. It is electrical. It is chemical.
B
When Na+ channels open, what happens to the Na+ ions? Na+ diffuses out of the cell. Na+ diffuses into the cell. Nothing happens because Na+ only moves when both the Na+ channels open and the Na+/K+ pump is active. There is an equal movement of Na+ into the cell and out of the cell.
B
When opposite charges are arranged on opposing sides of a membrane, the membrane is said to be ______. charged polarized facilitated capacitated
B
Within a chemical synapse, the receptors _____. are always degraded by enzymes in order disable them bind to very specific ligands are only responsive to changes in voltage bind to a variety of different ligands
B
Differentiate graded potentials and action potentials. Select all that apply. Summation of graded potentials can not occur but summation of action potentials are possible. Graded potentials are conducted in a decremental fashion and action potentials are conducted with a constant magnitude. The magnitude of graded potentials is variable and action potentials are all-or-none.
B C
Inhibitory postsynaptic potentials are due to the opening of ______ channels. Select all that apply. calcium potassium chloride sodium
B C
Identify the ions that have a higher concentration in the extracellular fluid compared to the intracellular fluid. Select all that apply. K+ Ca++ Cl- Na+
B C D
Identify the characteristics of graded potentials. Select all that apply . Irreversible Decremental All-or-none Graded Reversible
B D E
A nerve cell can only respond to an unusually strong stimulus during the ______ refractory period. rough absolute relative approximate
C
A period of time after a nerve cell has responded to a stimulus in which it cannot be re-excited by a threshold stimulus is called a(n) ______ period. inhibitory excitatory refractory latent
C
A protein channel that opens or closes in response to a stimulus would be classified as a ______ channel. stimulus gated leak
C
Because of its repulsion to the negatively charged proteins within the neurons, Cl- diffuses ______. equally in both directions across the membrane into the cell because of its attraction to K+ out of the cell and accumulates in the extracellular fluid within the cell via the endoplasmic reticulum
C
Binding of chemical signals to receptors, changes in membrane voltage, mechanical stimulation, temperature changes and spontaneous membrane changes can all cause ______ potentials. trigger resting membrane graded
C
Explain why Na+ has little effect on establishing the resting membrane potential? Cl- moves in at the same rate as Na+; therefore, the effect is offset. There are far more K+ channels in the membrane; therefore, Na+ has very little influence. At rest, the membrane is relatively impermeable to Na+ because there are few Na+ leak channels. Na+ is such a weak ion that it takes an enormous number to significantly affect membrane potential.
C
Identify the events that occurs toward the end of the repolarization phase The Na+ activation gates open and the inactivation gates close. Both the Na+ activation and inactivation gates open. The Na+ activation gates close and the inactivation gates open.
C
If a nerve signal grows weaker with distance from its origin, the nerve signal is described as being ______. self-propagating proportional decremental
C
Inhibitory postsynaptic potentials are due to the opening of ______ channels. sodium or chloride sodium or potassium chloride or potassium
C
Ion channels that are always open are called ______. voltage-gated channels ligand-gated channels leak channels
C
The ______ is proportional to the tendency of K+ to diffuse out of the cell and not to the actual rate of flow for K+. action potential graded potential resting membrane potential resting membrane concentration
C
The electrical signals that are propagated along axons, regulating and coordinating body activities, are known as _____. graded potentials neurotransmitters action potentials
C
The entry of calcium into the synaptic knob triggers ______. opening of sodium gates production of neurotransmitter exocytosis of neurotransmitter the development of a local potential
C
The slow closing of voltage-gated potassium channels is the cause of ______. depolarization repolarization hyperpolarization
C
The small, membrane-bound organelles that are found in the presynaptic terminals and which contain neurotransmitters are called _____. synaptic segments neurocontainers synaptic vesicles Nissl bodies
C
The sodium-potassium pump moves the ions in which direction? Both sodium and potassium into the cell Both sodium and potassium out of the cell Sodium out of the cell and potassium into the cell Sodium into the cell and potassium out of the cell
C
What effect will a neurotransmitter have on the postsynaptic membrane? It will always produce a depolarization. It will always produce a hyperpolarization. It may produce a depolarization or a hyperpolarization.
C
What is responsible for concentrating K+ inside and Na+ outside of neurons? Leak ion channels Ligand-gated ion channels Na+-K+ pumps Voltage-gated ion channels
C
When a neuron is at rest, ______ channels are open. voltage-gated ligand-gated leak
C
Which statement below best describes why Na+ is highly concentrated outside of neurons and K+ is concentrated within neurons? The neuron synthesizes the ions in these locations which is why they are concentrated there. K+is attracted to the interior of the cell by large negatively charged proteins and Na+ is repelled outward by the positive charges of K+. Na+ and K+ are actively pumped across the membrane in opposite directions by Na+/K+ pumps utilizing ATP. Na+ moves out of the cell through voltage-gated ion channels and K+ is drawn into the cell through ligand-gated ion channels.
C
_____ potentials are conducted in a decremental fashion, while ____ potentials are conducted with a constant magnitude. Membrane, graded Graded, membrane Action, graded Graded, action
C
A nerve cell can only respond to an unusually strong stimulus during the ______ refractory period. approximate rough absolute relative
D
Explain why Na+ ions diffuse into the neuron when the Na+ channels open. The Na+/K+ pump moves the Na+ into the cell when the Na+ channels open. The Na+ channel acts like a pump to actively move Na+ into the cell when the channels open. Because K+ moves out of the cell, the positive charges repel Na+, forcing Na+ ions to enter the cell. Na+ is more concentrated outside the cell than inside; hence, the concentration gradient causes diffusion into the cell.
D
In the region of the plasma membrane immediately adjacent to the area where the last action potential occurred, the entry of positive ions stimulates a new action potential. This kind of conduction is known as ______ conduction. graded potential local continuous
D
Ligand-gated ion channels bind ______ that have diffused across a synaptic cleft. water molecules ions ions neurotransmitters
D
The first neuron at a synapse (the end of an axon that releases neurotransmitter) would be the ______ neuron. primary synaptic postsynaptic antesynaptic presynaptic
D
The ion ______ is more concentrated in the extracellular fluid. phosphate potassium carbon sodium
D
The neuron plasma membrane is approximately _____ times more permeable to potassium ions than to sodium ions. 5-10 500-1000 5000-10,000 50-100
D
Which common ion associated with neuron function diffuses out of the cell due to its repulsion to the large intracellular proteins? K+ Na+ Ca++ Cl-
D
Which term best describes the concentration gradients for sodium and potassium on an excitable cell? Flat Shallow Non-existent Steep
D
True or false: As neurotransmitters diffuse away from the synaptic cleft, the amount of time that neurotransmitters remain bound to their receptors increases.
F
True or false: During the absolute refractory period a neuron will be re-stimulated if it reaches threshold.
F
True or false: In excitable tissues, the only channel types are ligand- and voltage-gated channels.
F
True or false: Na+ has the greatest influence on resting membrane potential due to its high permeability in the membrane.
F
True or false: Once achieved, a single action potential can travel the distance of the entire axon of the neuron.
F
True or False: Inhibitory postsynaptic potentials (IPSPs) involve hyperpolarization of the plasma membrane.
T
True or false: A neurotransmitter can have excitatory effects on one cell and inhibitory effects on another cell.
T
True or false: The potential difference is caused by a difference in concentration of charged particles on either side of the cell membrane.
T
True or false: The resting membrane potential is due to the tendency of K+ to diffuse out of the cell rather than the actual flow of K+.
T
True or false: There is a significant difference in concentration between the intracellular concentration of sodium and the extracellular concentration of sodium.
T
After a nerve cell responds to a stimulus, the period of time when the cell cannot respond again, regardless of the strength of stimulus, is called the _____ refractory period.
absolute
Electrical signals that are propagated along axons in a non-decremental fashion are called _____ potentials.
action
The period of hyperpolarization following an action potential is called _____
afterpotential
A postsynaptic cell may receive both inhibitory and _____ postsynaptic potentials.
excitatory
Hyperpolarization of a postsynaptic neuron in response to a neurotransmitter is called an _____ postsynaptic potential.
inhibitory
Neurotransmitter receptors at the postsynaptic membrane act as _____-regulated ion gates.
ligand
The intracellular fluid has essentially the same number of positive and negative charges and is therefore electrically _____
neutral or balanced
The gaps found between Schwann cells forming the myelin are referred to as the _____ of _____ .
node Ranvier
The plasma membrane has opposite charges arranged across the membrane and is thus said to be _____
polarized
The ion that is in a higher concentration in the intracellular fluid compared to the extracellular fluid is _____
potassium
When considering permeability to sodium and potassium, neuronal plasma membranes have a higher permeability to ______.
potassium
During an action potential of a neuron, the type of ion that enters the cell and causes depolarization is the _____ ion
sodium
The type of summation that involves a single synapse firing rapidly in sequence is called _____ summary
temporal
In order for an action potential to occur, a minimum membrane potential called the _____ must be reached.
threshold
An ion channel that opens when a specific electrical current is present on the cell membrane would be categorized as _____
voltage-gate
