Nervous System

    Nervous System
    Corticospinal pathways cross over from one side of the brain to the other side. Where does this crossover occur?
    In the medulla oblongata at the “decussation of pyramids”.
    Author: rikazzz Comment
    Nervous System
    Which of the following statements about the blood-brain barrier (BBB) is correct?
    Hormones and ions cannot pass through the BBB. (It is astrocytes, not Schwann cells, which form part of the BBB; the brain floats on CSF; CSF is formed by the choroid plexus).
    Author: rikazzz Comment
    Nervous System
    Which nerve cells carry impulses from the brain to the muscles?
    Motor (or efferent) nerves carry impulses away from the CNS to the muscles.
    Author: rikazzz Comment
    Nervous System
    Which structure carries incoming impulses towards the nerve cell body?
    Dendrites receive stimuli for nerve cells and transmit them towards the cell body. An axon transmits a nerve impulse away from the neurone cell body.
    Author: rikazzz Comment
    Nervous System
    What is meant by the “absolute refractory period” of a nerve cell membrane? The time during which:
    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).
    Author: rikazzz Comment
    Nervous System
    What is a spinal reflex?
    Brain processing is not involved but a synapse is. The response is not learned.
    Author: rikazzz Comment
    Nervous System
    If the frequency of a sound wave is increased from 50 to 3000 Hz, its loudness also increases. This occurs because:
    The ear as a hearing mechanism is able to better able to respond (detect) frequencies near 3000 Hz, whereas frequencies near 50 Hz are almost inaudible.
    Author: rikazzz Comment
    Nervous System
    In the human eye, where does the greatest refraction occur?
    Most refraction occurs as light enters the cornea because the difference between the refractive index of air and that of the cornea is large.
    Author: rikazzz Comment
    Nervous System
    Choose the true statement:
    Spinal reflexes are not learned nor used to diagnose brain death. Spinal reflexes are not under voluntary control.
    Author: rikazzz Comment
    Nervous System
    The sections of the cerebrum have their own names. What are these named structures known as?
    The cerebral cortex is divided into lobes.
    Author: rikazzz Comment