Animal Phys-Outlaw-Test 1-Chapter 4

T/F A change in membrane potential is typically more dependent on changes in the membrane permeability to an ion rather than changes in that ion's concentration.

T

T/F A smaller time constant translates into a faster speed of conduction.

T

T/F Acetylcholine is the neurotransmitter released from vertebrate motor neurons.

T

T/F An excitatory neurotransmitter typically causes a depolarization in the postsynaptic cell

T

T/F Cells using voltage-gated Ca2+ channels for depolarization tend to have longer periods of depolarization, which causes a longer refractory period.

T

T/F Different subtypes of receptors can be connected to different second messenger cascades in the interior of the cell.

T

T/F In a unipolar neuron, the process leading to the cell body has attributes of both an axon and a dendrite

T

T/F The axon hillock joins the cell body (soma) to the axon.

T

T/F The kinetics of voltage-gated K+ channels cause them to open and close more slowly than voltage-gated Na+ channels.

T

T/F Using myelin to increase the speed of conduction is beneficial because it means many neurons can fit into a small space

T

What mechanism causes the voltage-gated Na+ channels to close during an action potential? A. The activation gate is voltage sensitive and closes close to the equilibrium potential for Na+. B. The activation gate is sensitive to K+ and closes when its intracellular concentrations drop. C. The inactivation gate has a time-dependent closure. D. The inactivation gate is voltage sensitive and closes close to the equilibrium potential for Na+.

D. after-hyperpolarization phase

Neurons are capable of detecting and transducing incoming signals such as A. light. B. pressure. C. environmental chemicals. D. all of the above

D. all of the above

Neurotransmitters are composed of a variety of different chemicals, including A. amino acids. B. neuropeptides. C. biogenic amines. D. all of the above

D. all of the above

When considering spatial summation of graded potentials, it is important to keep in mind A. how far the potential may have traveled. B. the initial amplitude of the potential. C. the polarity of the potential. D. all of the above

D. all of the above

A membrane's length constant will be greatest when A. Rm is low. B. Ri is low. C. Rm is high. D. both B and C

D. both B and C

Metabotropic receptors typically generate a response by A. becoming an open channel as soon as the ligand binds. B. activating gene transcription. C. opening an ion channel via signaling from a second messenger cascade. D. both B and C

D. both B and C

What role does Ca2+ play in synaptic transmission? A. Ca2+ is released into the synapse, transmitting a signal to the postsynaptic cell. B. Ca2+ causes the release of vesicles from the readily releasable pool. C. Ca2+ causes vesicles to move from the storage pool to docking proteins. D. both B and C

D. both B and C

If a cell is at rest (-70 mV. and ligand-gated Na+ channels open, there will be a net movement of Na+ into the cell until A. there are no more Na+ in the extracellular fluid. B. the Na+ channels close. C. the membrane potential reaches the equilibrium potential for Na+. D. either B or C

D. either B or C

Which of the following is a true difference between electrical and chemical synapses? A. Electrical synapses are found in the central nervous system. B. Electrical synapses are the most common type of synapse. C. Electrical synapses typically send information in one direction (presynaptic cell to postsynaptic cell.. D. Electrical synapses are much faster.

D. electrical synapses are much faster

Action potentials are able to travel over long distances without decaying because A. the axons are perfectly insulated, so no current is able to leak out. B. the action potential uses completely different ions than graded potentials. C. once the electrical signal has passed threshold, it is impossible for the signal to decay. D. one action potential generates the next one in an adjacent area of membrane.

D. one action potential generates the next one in an adjacent area of membrane

A voltage-gated K+ channel that is also a delayed rectifier will A. open very quickly in response to changes in membrane potential. B. make it very difficult to start an action potential. C. delay the start of an action potential. D. open slowly, increasing the length of the action potential.

D. open slowly, increasing the length of the action potential.

T/F A single type of neurotransmitter can bind only to either ionotropic or metabotropic receptors, but not both.

F

T/F Action potentials are all-or-none events that are identical in all neurons of an organism, but may differ between organisms.

F

T/F Action potentials in plants, such as tomatoes, occur only in response to a harmful stimulus, such as wound generation.

F

T/F An action potential uses changes in its amplitude to carry information about the strength of a signal.

F

T/F During the relative refractory period of an action potential, it is impossible to generate a new action potential.

F

T/F Giant axons can be seen without aid of magnification and are up to one centimeter in diameter.

F

T/F Large numbers of ions must pass through ion channels to have an effect on membrane potential.

F

T/F Metazoans are the only organisms capable of producing electrical signals.

F

T/F Sarin and many organophosphate pesticides function by increasing the amount of acetylcholine release.

F

A cell will most likely hyperpolarize when ____________ enters it. A. Cl- B. Na+ C. Ca^2+ D. both B and C

A. Cl-

What is the correct relationship between graded potentials and action potentials? A. Graded potentials are used to generate action potentials. B. Action potentials are used to generate graded potentials. C. Graded potentials and action potentials are two terms for the same phenomenon. D. All graded potentials increase the likelihood of an action potential.

A. Graded potentials are used to generate action potentials

The strongest postsynaptic signal would be achieved by which of the following combinations? A. Low concentrations of neurotransmitter and postsynaptic receptors. B. High concentrations of neurotransmitter and degrading enzymes. C. Low concentrations of postsynaptic receptors and high concentrations of degrading enzymes. D. High concentrations of neurotransmitter and low concentrations of degrading enzymes.

A. Low concentrations of neurotransmitter and postsynaptic receptors

Which of the following statements is true of nerves? A. They are composed of groups of neurons. B. Neurons are composed of groups of nerves. C. They act as pipes in the body, transporting fluid. D. Signals generated in nerves can travel only short distances.

A. They are composed of groups of neurons

Which of the following neurotransmitters is typically NOT classified as a biogenic amine? A. acetylcholine B. serotonin C. epinephrine D. dopamine

A. acetylcholine

Movement of Na+ through its channels is primarily responsible for the __________ of an action potential. A. depolarization phase B. repolarization phase C. hyperpolarization phase D. after-hyperpolarization phase

A. depolarization potential

Myelination increases the speed of conduction by decreasing the time constant and increasing the length constant. It achieves this by A. increasing membrane resistance and decreasing capacitance. B. increasing both membrane resistance and capacitance. C. decreasing membrane resistance and increasing capacitance. D. decreasing both membrane resistance and capacitance.

A. increasing membrane resistance and decreasing capacitance

__________ neurons have many dendrites, but only one axon. A. Multipolar B. Bipolar C. Unipolar D. Pseudo-unipolar

A. multipolar

Given the information below, the neuron with the characteristics listed in choice __________ would have the fastest conduction velocity. A. myelinated, 50 μm diameter B. myelinated, 10 μm diameter C. unmyelinated, 50 μm diameter D. unmyelinated, 10 μm diameter

A. myelinated, 50 μm diameter

During synaptic transmission, A. the frequency of the action potential is directly correlated with neurotransmitter release. B. the frequency of the action potential is inversely correlated with neurotransmitter release. C. the intracellular concentration of Ca2+ remains stable because of intracellular buffers. D. the concentration of Ca2+ is inversely related to the amount of neurotransmitter released.

A. the frequency of the action potential is directly correlated with neurotransmitter release

The action potential of Chara, an algae species, is generated by A. Cl- efflux via voltage-gated channels. B. Cl- efflux via channels opened by second messenger pathways. C. Ca2+ influx via channels opened by second messenger pathways. D. Ca2+ efflux via voltage-gated channels

B. Cl- efflux via channels opened by second messenger pathways.

Which of the following statements is correct concerning the variation of voltage-gated ion channels? A. Na+ channels have much greater diversity than K+ channels. B. Typically, a more complex nervous system also contains a greater diversity of channels. C. There is a great diversity of channels, but within a single organism, only one isoform of a channel can exist. D. There is a large diversity of channels, but they show no physiological significance.

B. Typically, a more complex nervous system also contains a greater diversity of channels.

Which of the following graded potentials will be most likely to generate an action potential? A. a subthreshold potential B. a suprathreshold potential C. a hyperpolarizing potential D. an inhibitory potential

B. a suprathreshold potential

The synapse formed by __________ in the peripheral nervous system are similar in morphology to the __________ in the central nervous system. A. terminal boutons; axon varicosities B. axon varicosities; en passant synapses C. en passant synapses; spine synapse D. spine synapse; terminal boutons

B. axon varicosities; en passant synapses

Which of the following conditions could allow a cell to become depolarized? A. [X+]i > [X+]o B. change in permeability to [X+] C. membrane potential = equilibrium potential D. all of the above

B. change in permeability to [X+]

A motor neuron is an example of a type of A. afferent neuron. B. efferent neuron. C. interneuron. D. sensory neuron.

B. efferent neuron

The relative concentrations of Na+ and K+ remain constant during a single action potential, despite movement of these ions across the membrane, because A. they cross back immediately through recovery channels. B. they are pumped back across using the Na+/K+ ATPase pump. C. they are forced back across the membrane as the action potential moves away. D. the refractory periods do not end until all ions have been returned to their original areas.

B. they are pumped back across using the Na+/K+ ATPase pump

Which of the following statements is true of graded potentials? A. They travel over long distances. B. They have different amplitudes. C. They are typically found in axons. D. They travel without decrement.

B. they have different amplitudes

Which of the following properties of action potentials is unique to animals? A. They are a type of electrical signal. B. They travel at very rapid speeds. C. They may travel via intracellular connections. D. They allow the organism's cells to communicate with each other.

B. they travel at very rapid speeds

What is the benefit of using action potentials for conductance of electrical signals, rather than simply using electrotonic spread? A. Action potentials have a greater speed. B. Action potentials can vary in amplitude to convey more information. C. Action potentials can travel over longer distances. D. both A and C

C. Action potentials can travel over longer distances

When looking at a small patch of axonal membrane, the __________ and __________ are arranged in parallel with each other, allowing current to flow through both of them if possible. A. Rm; Ri B. Ri; Cm C. Rm; Cm D. Cm; Re

C. Rm; Cm

Which of the following statements is true about voltage-gated K+ channels? A. They are triggered to open at voltages near the Na+ equilibrium potential. B. They are triggered to open at voltages near the resting membrane potential. C. They are triggered to open at voltages near the threshold potential. D. They are triggered to open at voltages below the resting membrane potential.

C. They are triggered to open at voltages near the threshold potential

Axodendritic synapses are composed of __________ for the presynaptic cell and __________ for the postsynaptic cell. A. axons; axons B. dendrites; axons C. axons; dendrites D. axons; cell somas

C. axons; dendrites

The Goldman equation can be used to determine the resting membrane potential. It accounts for all the following factors EXCEPT A. concentration of an ion outside the cell. B. concentration of an ion inside the cell. C. concentration of all ion channels in the membrane. D. permeability of the membrane for the ions.

C. concentration of all ion channels in the membrane

Post-tetanic potentiation at a synapse is generated by a A. high frequency of stimulation. B. long period of time between stimuli. C. high frequency of stimulation followed by a short break. D. low frequency of stimulation followed by a short break.

C. high frequency of stimulation followed by a short break

A capacitor can store more change when it has a A. large surface area and thick insulating layer. B. small surface area and thin insulating layer. C. large surface area and thin insulating layer. D. small surface area and thick insulating layer.

C. large surface area and thin insulating layer

All the choices below are examples of glial cells, but which one is NOT associated with the central nervous system? A. microglia B. astrocytes C. schwann cells D. oligodendrocytes

C. schwann cells

__________ is a type of synaptic plasticity that results in a decrease of neurotransmitter release after repeated action potentials. A. Synaptic facilitation B. Post-tetanic potentiation C. Synaptic depression D. Presynaptic depression

C. synaptic depression

During the absolute refractory period, what is the state of the gates of the sodium channel? A. Both activation and inactivation gates are closed. B. Both activation and inactivation gates are open. C. The activation gate is open and the inactivation gate is closed. D. The activation gate is closed and the inactivation gate is open.

C. the activation gate is open and the inactivation gate is closed

The electrical signal produced by neurons, called an __________ __________, is capable of traveling over long distances.

action potential

__________ receptors bind both epinephrine and norepinephrine.

adrenergic

Axons are found in the __________ region of a neuron. A. signal reception B. signal integration C. signal conduction D. signal transmission

c. signal conduction

The membrane of an axon acts as a resistor and a __________ because it resists the flow of current and can store an electrical charge.

capacitor

Which of the following types of cells could be termed an excitable cell? A. endocrine cells B. muscle cells C. fertilized eggs D. all of the above

d. all of the above

When a cell __________, the charge difference between the intracellular and extracellular fluids decreases.

depolarizes

Synapses where pre- and postsynaptic cells are directly connected so that current can pass from one cell to another are called __________ _________

electrical synapses

Neurotransmitters are synthesized in the cell body, then transported in vesicles to the axon terminals using __________ __________ ___________.

fast axonal transport

Hodgkin and Huxley, who first showed electrical current was generated by selective permeability of the membrane to ions, used the __________ as a model system.

giant squid axon

When ligand-gated receptors open channels in dendrites, the resulting electrical signal is called a __________ __________.

graded potential

The distance a membrane potential can travel before reaching 37% of its original value is termed the __________ _________.

length constant

Muscarinic ACh receptors are an example of a __________ receptor, which eventually lead to the opening of an ion channel.

metabotropic

A __________ __________transmits signals from the central nervous system to skeletal muscles.

motor neuron

Oligodendrocytes and Schwann cells wrap themselves around neuronal processes, forming __________, a substance that increases conduction rates and decreases current leak.

myelin

Most neurons show __________, such that one end of the neuron receives a signal and the other sends a signal. The cnidarians are an exception to this principle.

polarity

Neurotransmitter is packaged in vesicles that are released in response to an action potential. This leads to a "steplike" increase in the amount of neurotransmitter being released (one step for each vesicle., termed __________ ________.

quantal release

__________, or afferent neurons, are capable of sending information about the environment (internal and external. to the central nervous system.

sensory

The channels that generate an action potential are triggered to open by a change in membrane potential because they are __________ channels.

voltage-gated

T/F A cell membrane can be depolarizing and repolarizing at the same time.

T

Increasing axon diameter decreases membrane and intracellular resistance, so it seems the two might cancel each other out in terms of their effect on the conduction speed. Yet, conduction speed is increased by increasing diameter size. Why? A. Membrane resistance doesn't really affect conduction speed that much. B. Intracellular resistance doesn't really affect conduction speed that much. C. Membrane resistance decreases linearly while intracellular resistance decreases by the square of the radius. D. Intracellular resistance decreases linearly while membrane resistance decreases by the square of the radius.

B. intracellular resistance doesn't really affect coduction speed that much

Which of the following combinations of voltage-gated channel densities would most easily allow an action potential to be generated? A. high density of K+, low density of Na+ B. low density of K+, high density of Na+ C. high density of K+ and Na+ D. low density of K+ and Na+

B. low density of K+, high density of Na+

In a neuromuscular junction, the muscle is the A. presynaptic cell. B. postsynaptic cell. C. synaptic cell. D. synapse.

B. postsynaptic cell

Neurons can produce and release different neurotransmitters. It is hypothesized that the type of neurotransmitter released is determined by A. the amplitude of the action potential. B. the frequency of the action potential. C. the neurotransmitter that is available. D. random chance.

B. the frequency of the action potential

Squid benefit from having axons of multiple sizes that innervate their muscle fibers in the mantle because A. squid need larger diameter axons to innervate larger groups of fibers. B. the larger diameter axons innervate fibers that are farther away because the signals are conducted more rapidly through them. C. smaller fibers are not energetically efficient. D. larger fibers generate larger action potentials, which allows for more neurotransmitter release.

B. the larger diameter axons innervate fibers that are farther away because the signals are conducted more rapidly through them

Conduction of action potentials along an axon is termed saltatory conduction because the action potential A. is dependent on the ions Na+ and K+, portions of salts. B. appears to leap or jump from node to node. C. is named after Johan Saltare, who first discovered it. D. moves very rapidly down the axon.

b. appears to leap or jump from node to node

The area of the axon covered with myelin and found between the nodes of Ranvier is known as an __________.

internode

Vesicles found in the axon terminals that contain neurotransmitter are called __________ _________.

synaptic vesicles

When a graded potential arrives at the axon hillock before an earlier graded potential has died out, the two potentials can be added in a process known as __________ __________.

temporal summation