Nervous System
What is meant by an absolute refractory period?
At least 5 ms must elapse from the time of the first action potential before a second can be initiated.
An action potential cannot be initiated during this period regardless of the strength of the stimulus.
An action potential can be initiated if the strength of the stimulus is higher than normal (>70 mV).
An action potential can be initiated if the strength of the stimulus is lower than normal (<70 mV).
An action potential cannot be initiated during this period regardless of the strength of the stimulus.
During the ~0.5 ms period of the action potential in which sodium ions are rushing into a nerve cell, the nerve cannot respond to any stimulus no matter how strong the stimulus is. Because of the impossibility of response, this period is called “absolutely” refractive (refractory = resisting ordinary methods).
An action potential cannot be initiated during this period regardless of the strength of the stimulus. During the ~0.5 ms period of the action potential in which sodium ions are rushing into a nerve cell, the nerve cannot respond to any stimulus no matter how strong the stimulus is. Because of the impossibility of response, this period is called “absolutely” refractive (refractory = resisting ordinary methods).
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In the spinal cord, the ascending tracts contain:A. White matter and transmit sensory information
B. White matter and transmit motor commands
C. Grey matter and transmit sensory information
D. Grey matter and transmit motor commands
Which sequence of ion movements describes the action potential?
A. Na+ move out of cell then K+ move in
B. K+ move in to cell then Na+ move out
C. K+ move out of cell then Na+ move in
D. Na+ move into cell then K+ move out
Which of the following substances is prevented from entering the brain by the blood-brain barrier?
A. Glucose
B. Nicotine
C. Pharmaceuticals
D. Alcohol
There are three ossicles in the middle ear. What are their names?
A. Malleus, stapedius, otolith
B. Cochlea, stapes, incus
C. Stapedius, ampulla, cochlea
D. Malleus, stapes, incus
The inner ear (or internal ear) may be described as a series of tubes. What are the tubes filled with?
A. Air
B. Perilymph
C. Endolymph
D. Perilymph and endolymph
What characterises a spinal reflex?
A. It involves rapid processing by the brain and a predictable response.
B. It is a predictable, unlearned and involuntary motor response.
C. It is a rapid, predictable, learned and involuntary motor response.
D. It involves stimulation of a motor neurone by a sensory neurone that originates within the CNS.
A multipolar neuron has more than one of what?
A. Dendrite attached to the cell body
B. Axon attached to the cell body
C. Synaptic terminal attached to the axon
D. Cell body
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