TEST 3 A&P Q233 other member

Which selection correctly describes the role of calcium in coupling? Calcium binds to actin, which triggers troponin to fall off and expose myosin-binding sites. Calcium binds to tropomyosin, which moves tropomyosin and exposes the myosin-binding sites on actin. Calcium binds to troponin, which moves tropomyosin and exposes the myosin-binding sites on actin. Calcium binds to actin, which triggers it to bind to myosin.

Calcium binds to troponin, which moves tropomyosin and exposes the myosin-binding sites on actin.

What is the role of calcium in synaptic activity? Calcium diffuses across the synaptic cleft and binds to receptors on the postsynaptic neuron. Calcium influx into the synaptic terminal causes vesicle fusion. Calcium degrades neurotransmitter in the synaptic cleft. Calcium influx into the axon causes an action potential to propagate into the synaptic terminal.

Calcium influx into the synaptic terminal causes vesicle fusion.

Which best describes the initial event in contraction? Myosin heads bind to the newly exposed myosin-binding sites on actin to form cross bridges. The myofilaments slide closer together. Tropomyosin binds to myosin heads and actin bridges with tropomyosin. Calcium binds actin to myosin to begin the cross bridge cycle.

Myosin heads bind to the newly exposed myosin-binding sites on actin to form cross bridges

What is the role of neurotransmitter at a chemical synapse? Neurotransmitter causes vesicles to fuse with the presynaptic membrane. Neurotransmitter binds to receptors on the postsynaptic cell membrane and allows ions to diffuse across the membrane. Neurotransmitter causes a graded potential in the postsynaptic cell. Neurotransmitter causes calcium to flood into the presynaptic cell.

Neurotransmitter binds to receptors on the postsynaptic cell membrane and allows ions to diffuse across the membrane.

Which of the following is true about the movement of ions across excitable living membranes? Ions always move actively across membranes through leakage channels. Ions always move passively across membranes. Sodium gates in the membrane can open in response to electrical potential changes. Ions always move from an area of higher concentration to an area of lower concentration

Sodium gates in the membrane can open in response to electrical potential changes.

A patient is admitted to the hospital with exacerbation of multiple sclerosis (MS). She asks the nurse "Why did this have to happen to me again? I was doing so well." Why are some forms of MS characterized by periods of remission and exacerbation? The axons are damaged, and repair of the axons results in impulse propagation resuming. The axons are not damaged; growing numbers of sodium channels appear spontaneously in the demyelinated fibers, allowing conduction to resume. The axons are damaged, and repair of the myelin sheath results in impulse propagation resuming. The axons are not damaged; growing numbers of potassium channels appear spontaneously in the demyelinated fibers, allowing conduction to resume. The myelin sheaths are damaged, and repair of the myelin sheaths results in impulse propagation resuming.

The axons are not damaged; growing numbers of sodium channels appear spontaneously in the demyelinated fibers, allowing conduction to resume.

Which of the following is NOT true of an electrical synapse? Transmission across these synapses is very rapid. Communication through these synapses may be unidirectional or bidirectional. They are specialized for release and reception of chemical neurotransmitters. They are less common than chemical synapses.

They are specialized for release and reception of chemical neurotransmitters.

Which of the following is not true of graded potentials? They can be called postsynaptic potentials. They are short-lived. They can form on receptor endings. They increase amplitude as they move away from the stimulus point.

They increase amplitude as they move away from the stimulus point.

What type of channel on the postsynaptic membrane binds neurotransmitter? a mechanically gated channel a leakage channel a voltage-gated channel a chemically gated channel

a chemically gated channel

A postsynaptic cell can be a neuron, a muscle cell, or a secretory cell. What is an example of a presynaptic cell? a muscle cell a Schwann cell a neuron a secretory cell

a neuron

What type of stimulus is required for an action potential to be generated? a suprathreshold stimulus hyperpolarization a threshold level depolarization multiple stimuli

a threshold level depolarization

The period after an initial stimulus when a neuron is not sensitive to another stimulus is the ________. depolarization repolarization absolute refractory period resting period

absolute refractory period

The mechanism by which the neurotransmitter is returned to a presynaptic neuron's axon terminal is specific for each neurotransmitter. Which of the following neurotransmitters is broken down by an enzyme before being returned? glutamate acetylcholine

acetylcholine

Which of the following is an excitatory neurotransmitter secreted by motor neurons innervating skeletal muscle? gamma aminobutyric acid norepinephrine cholinesterase acetylcholine

acetylcholine

Which of the following correctly describes a graded potential? amplitude of various sizes long distance signaling voltage stimulus to initiate voltage regulated repolarization

amplitude of various sizes

Which component has a role in the postsynaptic cell during synaptic activity? calcium channels Vesicles filled with neurotransmitter axon terminal chemically gated channels

chemically gated channels

Binding of a neurotransmitter to its receptors opens __________ channels on the __________ membrane. chemically gated; presynaptic voltage-gated; presynaptic voltage-gated; postsynaptic chemically gated; postsynaptic

chemically gated; postsynaptic

Which of the following is NOT one of the chemical classes into which neurotransmitters fall? peptides gases and lipids amino acids chlorides

chlorides

What is the role of acetylcholinesterase? act as a transmitting agent amplify or enhance the effect of ACh destroy ACh a brief period after its release by the axon endings stimulate the production of acetylcholine

destroy ACh a brief period after its release by the axon endings

Binding of the neurotransmitter to its receptor causes the membrane to __________. either depolarize or hyperpolarize hyperpolarize depolarize

either depolarize or hyperpolarize

Which membrane potential occurs because of the influx of Na+ through chemically gated channels in the receptive region of a neuron? action potential inhibitory action potential excitatory postsynaptic potential inhibitory postsynaptic potential

excitatory postsynaptic potential

Neurotransmitter is released from presynaptic neurons through what mechanism? exocytosis phagocytosis pinocytosis endocytosis

exocytosis

What does the central nervous system use to determine the strength of a stimulus? origin of the stimulus type of stimulus receptor size of action potentials frequency of action potentials

frequency of action potentials

When a sensory neuron is excited by some form of energy, the resulting graded potential is called a(n) ________. postsynaptic potential excitatory potential generator potential action potential

generator potential

An inhibitory postsynaptic potential (IPSP) is associated with ________. lowering the threshold for an action potential to occur opening of voltage-regulated channels a change in sodium ion permeability hyperpolarization

hyperpolarization

When neurotransmitter molecules bind to receptors in the plasma membrane of the receiving neuron, ion channels in the plasma membrane of the receiving neuron open. the receiving neuron becomes more negative inside. vesicles in the synaptic terminal fuse to the plasma membrane of the sending neuron. ion channels in the plasma membrane of the sending neuron open. the receiving neuron becomes more positive inside.

ion channels in the plasma membrane of the receiving neuron open.

In what way does the interior surface of a cell membrane of a resting (nonconducting) neuron differ from the external environment? The interior is ________. positively charged and contains more sodium negatively charged and contains less sodium negatively charged and contains more sodium positively charged and contains less sodium

negatively charged and contains less sodium

The substance released at axon terminals to propagate a nervous impulse is called a(n) ________. cholinesterase ion neurotransmitter biogenic amine

neurotransmitter

A molecule that carries information across a synaptic cleft is a synaptic cleft. sending neuron. neurotransmitter. receiving neuron. synapse.

neurotransmitter.

Immediately after an action potential has peaked, which cellular gates open? calcium chloride potassium sodium

potassium

Which of the following is NOT a type of circuit? pre-discharge circuits reverberating circuits diverging circuits converging circuits

pre-discharge circuits

In a synapse, neurotransmitters are stored in vesicles located in the __________. postsynaptic neuron synaptic cleft presynaptic neuron

presynaptic neuron

The __________ is due to the difference in K+ and Na+ concentrations on either side of the plasma membrane, and the difference in permeability of the membrane to these ions. active potential intermittent membrane potential dendrite potential resting membrane potential

resting membrane potential

In addition to diffusion, what are two other mechanisms that terminate neurotransmitter activity? reuptake and degradation exocytosis and degradation excitation and degradation reuptake and inhibition

reuptake and degradation

Which of the following circuit types is involved in the control of rhythmic activities such as the sleep-wake cycle, breathing, and certain motor activities (such as arm swinging when walking)? diverging circuits parallel after-discharge circuits reverberating circuits converging circuits

reverberating circuits

Which pattern of neural processing works in a predictable, all-or-nothing manner, where reflexes are rapid and automatic responses to stimuli in which a particular stimulus always causes the same response? oscillative processing reflexive processing serial processing parallel processing

serial processing

Which of the following describes the excitatory postsynaptic potential? moves membrane potential away from threshold opens K+ or Cl- channels short distance hyperpolarization short distance depolarization

short distance depolarization

An impulse from one nerve cell is communicated to another nerve cell via the ________. receptor cell body effector synapse

synapse

The small space between the sending neuron and the receiving neuron is the synaptic cleft. synaptic terminal. calcium channel. neurotransmitter. vesicle.

synaptic cleft.

If a motor neuron in the body were stimulated by an electrode placed about midpoint along the length of the axon ________. the impulse would move to the axon terminal only muscle contraction would occur the impulse would spread bidirectionally the impulse would move to the axon terminal only, and the muscle contraction would occur

the impulse would spread bidirectionally

A second nerve impulse cannot be generated until ________. the Na ions have been pumped back into the cell all sodium gates are closed proteins have been resynthesized the membrane potential has been reestablished

the membrane potential has been reestablished

Saltatory conduction is made possible by ________. diphasic impulses large nerve fibers erratic transmission of nerve impulses the myelin sheath

the myelin sheath

If a signal from a sending neuron makes the receiving neuron more negative inside, the receiving neuron immediately generates an action potential. the sending neuron becomes more positive inside. the sending neuron becomes more negative inside. the receiving neuron is more likely to generate an action potential. the receiving neuron is less likely to generate an action potential

the receiving neuron is less likely to generate an action potential.

Select the correct statement regarding synapses. Neurotransmitter receptors are located on the axons terminals of cells. The release of neurotransmitter molecules gives cells the property of being electrically coupled. Cells with gap junctions use chemical synapases. The synaptic cleft prevents an impulse from being transmitted directly from one neuron to another.

the synaptic cleft prevents an impulse from being transmitted directly from one neuron to another.

When calcium ions enter the synaptic terminal, they cause an action potential in the sending neuron. the inside of the receiving neuron becomes more negative. they cause vesicles containing neurotransmitter molecules to fuse to the plasma membrane of the sending neuron. neurotransmitter molecules are quickly removed from the synaptic cleft. the inside of the receiving neuron becomes more positive.

they cause vesicles containing neurotransmitter molecules to fuse to the plasma membrane of the sending neuron.

A stimulus traveling toward a synapse appears to open calcium ion channels at the presynaptic end, which in turn promotes fusion of synaptic vesicles to the axonal membrane. True False

true

Axon diameter and degree of myelination determine nerve impulse conduction velocity. True False

true

In myelinated axons the voltage-regulated sodium channels are concentrated at the nodes of Ranvier. True False

true

Some neurotransmitters can be either excitatory or inhibitory depending upon the receptor. True False

true

The action potential is caused by permeability changes in the plasma membrane. True False

true

An action potential releases neurotransmitter from a neuron by opening which of the following channels? voltage-gated Ca2+ channels chemically gated Ca2+ channels voltage-gated Na+ channels voltage-gated K+ channels

voltage-gated Ca2+ channels

Which ion channel opens in response to a change in membrane potential and participates in the generation and conduction of action potentials? leakage channel mechanically gated channel ligand-gated channel voltage-gated channel

voltage-gated channel

Events that occur during synaptic activity are listed here, but they are arranged in an incorrect order. Choose the correct order of these events below. (a) Voltage-gated calcium channels open (b) Neurotransmitter binds to receptors (c) Action potential arrives at axon terminal (d) Neurotransmitter is removed from the synaptic cleft (e) Neurotransmitter released into synaptic cleft (f) Graded potential generated in postsynaptic cell (c) Action potential arrives at axon terminal (a) Voltage-gated calcium channels open (e) Neurotransmitter released into synaptic cleft (b) Neurotransmitter binds to receptors (f) Graded potential generated in postsynaptic cell (d) Neurotransmitter is removed from the synaptic cleft (c) Action potential arrives at axon terminal (a) Voltage-gated calcium channels open (e) Neurotransmitter released into the synaptic cleft (d) Neurotransmitter is removed from the synaptic cleft (b) Neurotransmitter binds to receptors (f) Graded potential generated in postsynaptic cell (a) Voltage-gated calcium channels open (e) Neurotransmitter released into the synaptic cleft (c) Action potential arrives at axon terminal (b) Neurotransmitter binds to receptors (f) Graded potential generated in postsynaptic cell (d) Neurotransmitter is removed from the synaptic cleft (d) Neurotransmitter is removed from the synaptic cleft (b) Neurotransmitter binds to receptors (f) Graded potential generated in postsynaptic cell (c) Action potential arrives at axon terminal (a) Voltage-gated calcium channels open (e) Neurotransmitter released into the synaptic cleft

(c) Action potential arrives at axon terminal (a) Voltage-gated calcium channels open (e) Neurotransmitter released into synaptic cleft (b) Neurotransmitter binds to receptors (f) Graded potential generated in postsynaptic cell (d) Neurotransmitter is removed from the synaptic cleft

Correct Graded potentials originating in the dendrites and cell body are integrated (summated) at the axon hillock (C). Membrane potentials above threshold at the hillock will open voltage gated Na+ channels found in the "trigger zone," producing an action potential that proceeds down the axon.

...

Which of the following is false or incorrect? An inhibitory postsynaptic potential occurs if the inhibitory effect is greater than the excitatory, causing hyperpolarization of the membrane. An excitatory postsynaptic potential occurs if the excitatory effect is greater than the inhibitory effect but less than threshold. A nerve impulse occurs if the excitatory and inhibitory effects are equal.

A nerve impulse occurs if the excitatory and inhibitory effects are equal.

Which of the following statements best summarizes excitation-contraction coupling? A series of events in which an electrical stimulus is conveyed to a muscle fiber to enact contraction. A series of events in which actin binds myosin to enact contraction. A series of events in which calcium gradients are used to convey a signal to the muscle fiber to enact contraction. A series of events in which an action potential triggers the release of chemical messengers.

A series of events in which an electrical stimulus is conveyed to a muscle fiber to enact contraction.

Which of the following will occur when an excitatory postsynaptic potential (EPSP) is being generated on the dendritic membrane? A single type of channel will open, permitting simultaneous flow of sodium and potassium. Sodium gates will open first, then close as potassium gates open. Specific sodium gates will open. Specific potassium gates will open.

A single type of channel will open, permitting simultaneous flow of sodium and potassium.