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Frederick James
Physiology Week 7
| Question | Answer |
|---|---|
| In a myelinated fiber, the action potential jumps from one node of Ranvier to the next. | True |
| Neurons are the only living cells that maintain a difference in the concentration of ions across their membranes. | False |
| 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. |
| The action potential seems to “leap” from node to node along a myelinated fiber. This type of impulse regeneration is called __________ conduction. | saltatory |
| If the threshold potential is surpassed, the full peak of the action potential is always reached. | True |
| 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 |
| A membrane that exhibits a membrane potential is said to be | polarized |
| The magnitude of the action potential peaks when the sodium channels close. | True |
| The speed of a nerve impulse depends on the neuron’s resting potential. | False |
| If the magnitude of the local depolarization surpasses a limit called the _____, voltage-gated Na+ channels are stimulated to open. | threshold potential |
| What mechanism quickly terminates the action of a neurotransmitter once it binds to its postsynaptic receptor? | Neurotransmitter molecules are transported into nearby glial cells. Neurotransmitter molecules are transported back into synaptic knobs. Neurotransmitter molecules are metabolized into inactive compounds. Are all correct. |
| When a neuron is resting, the inner surface of its plasma membrane is slightly positive compared with its outer surface. | False |
| The tiny bulge at the end of a terminal branch of a presynaptic neuron’s axon is called a(n) | synaptic knob |
| 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: | another axon. a cell body a dendrite any of above is correct any of above is correct |
| A term commonly used as a synonym for action potential is | nerve impulse |
| There are two types of synapses—the electrical synapse and the __________ synapse. | chemical |
| The membrane potential maintained by a nonconducting neuron’s plasma membrane is called the _____ membrane potential. | resting |
| The sodium-potassium pump actively pumps three potassium ions out of the neuron and two sodium ions into the neuron. | False |
| The brief period during which a local area of an axon's membrane resists re-stimulation is called the __________ period. | refractory |
| In depolarization the membrane potential moves toward zero, whereas in hyperpolarization the membrane potential moves away from zero. | 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. |
| Whether an impulse is continued through the neuron depends on the magnitude of the voltage in the axon hillock. | True |
| An ion channel that opens in response to a sensory stimulus is a(n) | stimulus-gated channel |
| Movement of the membrane potential away from zero (below the usual RMP) is called | hyperpolarization. |
| 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. |
| Which chemicals allow neurons to communicate with one another? | neurotransmitter |
| Which membrane receptor acts to directly change ion permeability when stimulated? | Gated-channel receptor |
| In a myelinated neuron, the impulse can travel under the myelin between nodes of Ranvier. | True |
| The difference in electrical charge between the inside and outside of a membrane is called the membrane potential. | True |
| Which is true of a neuron with a resting potential? | The sodium pump has moved Na+ to the outside of the plasma membrane. |
| No impulse can be sent through a neuron: | during the absolute refractory period. |
| When an impulse reaches a synapse: | chemical transmitters are released. |
| Neurotransmitters are released in a synapse and bind to: | receptors on the postsynaptic neuron. |
| Which neuron could transmit a nerve impulse the fastest? | A large-diameter neuron with myelin |
| Which of the following is not one of the main chemical classes of neurotransmitters? | Triglycerides |
| Acetylcholine is in the same class of neurotransmitters as: | serotonin. histamine. dopamine. none of the above is correct. none of the above is correct. |
| Severe depression can be caused by a deficit in certain brain synapses of: | amines |
| The only ion(s) that can diffuse across a neuron’s membrane when the neuron is at rest is (are): | potassium |
| 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 |
| Excitatory neurotransmitters are most likely to: | initiate an action potential |
| There are two types of synapses—the electrical synapse and the __________ synapse. | chemical |
| Compared with the outside of the neuron, the inside has a(n) ____ charge. | negative |
| 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. |
| Which of the following is not used by the body as a neurotransmitter? | Nitric oxide Acetylcholine Carbon monoxide All of the above are used by the body as neurotransmitters. All of the above are used by the body as neurotransmitters. |
| Dopamine, epinephrine, and norepinephrine are classified as: | catecholamines. |
| A synapse consists of: | a synaptic knob. a synaptic cleft. the plasma membrane of a postsynaptic neuron. all of the above. all of the above. |
| Within the nervous system, coding for the strength of a stimulus is accomplished through: | the frequency of nerve impulses. |
| A slight shift away from the resting membrane potentials in a specific region of the plasma membrane is called a _____ potential. | local |
| Stimulus-gated channels open in response to: | sensory stimuli. |
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jamesfj
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