1. Assume you could “look” into the musculature of an animal and watch neurosece
ID: 50018 • Letter: 1
Question
1. Assume you could “look” into the musculature of an animal and watch neurosecetion as an animal moved. What would you see?
a. dynamic neurosecretion b. dynamic patterns of neurosecretion
2. The word organ denotes a distinct set of tissues performing one or more specific functions. Therefore, this term can be used to refer to large visceral organs, e.g. the liver, or much smaller structures such as otolith organs. In regard to the otolith organs, what causes the cilia of their vestibular cells to bend?
a, shear force b. inertia of endolymph
3. Recall that the vestibulo-ocular reflex enables the eyes to remain fixed on target and that extrinsic eye muscles are innervated by brainstem -motor neurons. What role does the medial longitudinal fasciculus play in the vestibulo-ocular reflex?
a. central integration b. links the vestibular nuclei with brainstem motor nuclei
4. Descending projections from the vestibular nuclei enable postural adjustments of the head and body. Any stereotypical change in head position that promotes balance is mediated by the vestibulo-cervical reflex. This name stems from the fact that most of the -motor neurons that control the position of the head are located in the motor nuclei of the
a. brainstem b. cervical cord
5. Any stereotypical change in body position that promotes balance is mediated by the vestibulo-spinal reflex. Does this reflex implement the -loop?
a. yes b. no
Explanation / Answer
1. b. dynamic patterns of neurosecretion
We can observe the dymanic patterns of neurosecretion during contraction and relaxation of muscles (may be opposing or synergistic) controlling the posture against gravity.
2. a, shear force
“Vestibule” is the central part of the inner ear, and it lies between cochlea and semicircular canals. It contains utricle and saccule which are parts of membranous labyrinth. Maculae in the vestibule contains sensory receptors called, hair cells, which are essential to the mechanism of static equilibrium. The hair cells of maculae are embedded in the “otolithic membrane,” which contains small grains of calcium carbonate, called otoliths.
The maculae provide the information regarding the ups and downs of a path and to linear changes in speed, as it responds to the gravitational pull by means of otoliths. According to the gravitational pull (in this case, acceleration of the head), the otoliths cause the hair cells to depolarise or hyperpolarise, and then these hair cells send action potentials to the vestibular part of the eighth cranial nerve (vestibulocochlear nerve).
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