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Jessica Feltner
Physiology Week 7
Question | Answer |
---|---|
In a myelinated neuron, the impulse can travel under the myelin between nodes of Ranvier | True |
A term commonly used as a synonym for action potential is | nerve impulse |
The tiny bulge at the end of a terminal branch of a presynaptic neuron’s axon is called a(n) | synaptic knob |
In depolarization the membrane potential moves toward zero, whereas in hyperpolarization the membrane potential moves away from zero | True |
In a myelinated fiber, the action potential jumps from one node of Ranvier to the next | True |
The mechanisms that produce and maintain the resting membrane potential do so by producing a | slight excess of positive ions on the outer surface of the plasma membrane |
When neurotransmitters from synaptic knobs stimulate a postsynaptic neuron in rapid succession, their effect can add up over a brief period to produce an action potential. This is called | temporal summation |
Neurons are the only living cells that maintain a difference in the concentration of ions across their membranes | False |
The difference in electrical charge between the inside and outside of a membrane is called the membrane potential | True |
When a neuron is resting, the inner surface of its plasma membrane is slightly positive compared with its outer surface | False |
A neurologist is using a voltmeter to measure potential. The membrane potential of a neuron was recorded at +30 mV. This is what type of membrane potential? | Action |
The magnitude of the action potential peaks when the sodium channels close | True |
The sodium-potassium pump actively pumps three potassium ions out of the neuron and two sodium ions into the neuron | False |
The active transport mechanism in the plasma membrane that transports sodium and potassium ions in opposite directions and at different rates is the | sodium-potassium pump |
A synapse can occur only between an axon and: | any of the above |
Movement of the membrane potential away from zero (below the usual RMP) is called | hyperpolarization |
Which chemicals allow neurons to communicate with one another? | neurotransmitters |
An ion channel that opens in response to a sensory stimulus is a(n) | stimulus-gated channel |
The action potential seems to “leap” from node to node along a myelinated fiber. This type of impulse regeneration is called __________ conduction | saltatory |
The difference between sodium and potassium in the generation of action potential is that: | sodium causes depolarization of the cell membrane, and potassium causes repolarization of the cell membrane |
A membrane that exhibits a membrane potential is said to be | polarized |
The brief period during which a local area of an axon's membrane resists re-stimulation is called the __________ period | refactory |
What mechanism quickly terminates the action of a neurotransmitter once it binds to its postsynaptic receptor? | all are correct |
The membrane potential maintained by a nonconducting neuron’s plasma membrane is called the _____ membrane potential. | resting |
There are two types of synapses—the electrical synapse and the __________ synapse | chemical |
Which membrane receptor acts to directly change ion permeability when stimulated? | Gated-channel receptor |
If the threshold potential is surpassed, the full peak of the action potential is always reached. | True |
Whether an impulse is continued through the neuron depends on the magnitude of the voltage in the axon hillock | True |
If the magnitude of the local depolarization surpasses a limit called the _____, voltage-gated Na+ channels are stimulated to open | threshold potential |
The speed of a nerve impulse depends on the neuron’s resting potential | False |
Which of the following is not used by the body as a neurotransmitter? | All are used as neurotransmitters |
Which of the following statements about amino acid neurotransmitters is incorrect? | They are all inhibitory neurotransmitters |
For a neurotransmitter to produce an inhibitory postsynaptic potential, which of the following channels must open? | Potassium and/or chloride channels |
Which of the following is not one of the main chemical classes of neurotransmitters? | Triglycerides |
The first event to occur when an adequate stimulus is applied to a neuron is: | some of the sodium channels at the point of stimulation open |
Compared with the outside of the neuron, the inside has a(n) ____ charge | negative |
When current leaps across an insulating myelin sheath from node to node, the type of impulse conduction is called: | saltatory conduction |
Stimulus-gated channels open in response to: | sensory stimuli |
The only ion(s) that can diffuse across a neuron’s membrane when the neuron is at rest is (are): | potassium |
Which of the following antidepressants acts by blocking the action of monoamine oxidase (MAO)? | Phenelzine |
Serotonin is an example of a(n): | amine neurotransmitter |
Which is true of a neuron with a resting potential? | The sodium pump has moved Na+ to the outside of the plasma membrane |
Acetylcholine is in the same class of neurotransmitters as: | none of the above |
The fastest nerve fibers in the body can conduct impulses up to approximately _____ meters per second. | 130 |
Severe depression can be caused by a deficit in certain brain synapses of: | amines |
A slight shift away from the resting membrane potentials in a specific region of the plasma membrane is called a _____ potential | local |
No impulse can be sent through a neuron: | during the absolute refractory period |
The neurotransmitter(s) that inhibit(s) the conduction of pain impulses is(are): | enkephalins |
Dopamine, epinephrine, and norepinephrine are classified as: | catecholamines |
Which of the following is true of spatial summation? | Neurotransmitters released simultaneously from several presynaptic knobs converge on one postsynaptic neuron |
Neurotransmitters are released in a synapse and bind to: | receptors on the postsynaptic neuron |
Which is true of an action potential? | The outside of the plasma membrane is negatively charged, and the inside is positively charged |
During a relative refractory period: | the action potential can be initiated with a strong stimulus |
Within the nervous system, coding for the strength of a stimulus is accomplished through: | the frequency of nerve impulses |
Excitatory neurotransmitters are most likely to: | initiate an action potential |
When an impulse reaches a synapse: | chemical transmitters are released |
The fastest nerve fibers in the body can conduct an impulse that is how much faster than the slowest fibers in the body? | Almost 300 times faster |
Which neuron could transmit a nerve impulse the fastest? | A large-diameter neuron with myelin |
A synapse consists of: | all of the above |
A synaptic knob would be located on a(n): | axon |