Nervous System
What would happen if a neuron lost its myelin sheath?
Na+ would leak out of the axon leaving too few ions to stimulate the Na channels at the next node to open.
The neuron would die.
More Na+ channels would be exposed allowing freer entry so conduction speed would increase.
More K+ channels would be exposed allowing freer exit so the cell would hyperpolarise.
Na+ would leak out of the axon leaving too few ions to stimulate the Na channels at the next node to open.
The myelin sheath prevents sodium ions from leaking back into the intracellular fluid; hence, they can travel with minimum diminution to the next node to trigger the opening of abundant voltage-gated sodium channels.
Na+ would leak out of the axon leaving too few ions to stimulate the Na channels at the next node to open. The myelin sheath prevents sodium ions from leaking back into the intracellular fluid; hence, they can travel with minimum diminution to the next node to trigger the opening of abundant voltage-gated sodium channels.
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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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