Flashcards in Exteroception Deck (17):
Intensity is a product of ___________.
increase in frequency
Ruffini's ending cells are ____________.
free nerve endings (they're out in the "rough")
Describe the different territory sizes for Meissner's corpuscles, Pacinian corpuscles, Ruffini's endings, and Merkel's disks.
Meissner's and Merkel's are small (Miniature), and Pacinian's and Ruffini are big
Which kinds of exteroception receptors are fast-adapting and slow-adapting?
Fast: Meissner's and Pacinian
Slow: Ruffini and Merkel
The nucleus gracilis and nucleus cuneatus reside in the _________ aspect of the caudal medulla.
The medial lemniscus passes __________ in the caudal medulla before ascending to the brain.
anterior and then contralateral (that is, it comes toward the front of the body and then crosses the midline)
Describe the differences in the passage of the trigeminal (compared to the passage of normal vibration nerves).
The trigeminal nerve passes into the mid-pons and synapses in a nucleus analogous to the posteromarginal nucleus. From there it crosses immediately to the contralateral side of the pons (whereas in the lower areas the axons would ascend to the nucleus gracilis before crossing) and then joins the medial lemniscus.
The precentral gyrus is Brodmann area _______.
The gray matter immediately deep to the central sulcus is _______
3a – muscle receptors
Explain the difference between slow-adapting and fast-adapting neurons.
Fast-adapting sensory cells will stop firing action potentials if a stimulus is repeated in quick succession. Slow-adapting sensory cells will keep firing action potentials even if the stimulus is repeated many times in quick succession.
How large are the small sensory fields in the hand (that is, those innervated by Meissner's corpuscles and Merkel's discs)?
2-8 mm in diameter
Small sensory fields in the hand are also distinguished by what other feature?
Having sharply defined borders
True or false: the sensory neurons that mediate the stretch reflex response are A-beta.
False! A-beta neurons are mechanoreceptors of the skin – A-alpha neurons innervate the muscles and tendons and bifurcate in the spine to innervate muscles.
The lemniscal tract for sensory information from the head synapses on what thalamic nucleus?
The ventral-posterior-medial nucleus
Describe the phenomenon of cortical barrels.
There are distinct vertical columns of cells that correspond to a specific sense field. For instance, each whisker of a rodent has been found to have a special column of cells in the somatosensory cortex.
True or false: skin mechanoreceptors terminate in 3b within the somatosensory cortex.