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The sensory nervous system
describes the sensory nervous system for Systems or Integrative neuroscience
92
Anatomy
Graduate
03/04/2013

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Term
Name a few characteristics of free nerve endings
Definition
minimal specialization; C & Adelta axons; transmit pain, temperature and touch; are slowly adapting; have a high threshold of activation
Term
Name a few characteristics of Meissner's corpuscles
Definition
Encapsulated between dermal papillae; project to ABeta axons; located in glaborous skin; pressure sensitive; rapidly adapt; low threshold of activation
Term
Name a few characteristics of Pacinian corpuscles
Definition
Encapsulated onion like covering; project to Abeta axons; found in subcutaneous tissue; detect deep pressure and vibration; rapidly adapting;low threshold of activation
Term
Name a few characteristics of Merkel's disks
Definition
Encapsulated and associated with peptide releasing cells; project to Abeta axons; located in all skin, hair follicles; touch sensitive; slowly adapting; low threshold of activation
Term
Name a few characteristics of Ruffini's corpuscles
Definition
Encapsulated and oriented along stretch lines; project to Abeta axons; found in all skin; detect stretching ; slowly adapting; low threshold of activation
Term
Name a few characteristics of Muscle spindles
Definition
Associated with Ia and II axons; found in muscles; detect muscle length; can be either rapid or slowly adapting; low threshold of activation
Term
Name a few characteristics of Golgi tendon organs
Definition
Detect muscle tension; project to Ib axons; located in tendons; slowly adapting; low threshold of activation
Term
Convergence
Definition
when two nerves receving a stimulus terminate on one first order neuron
Term
Divergence
Definition
when one primary sensory neuron terminates on two first order neurons
Term
Centrifugal feedback
Definition
when a nerve inhibits the nerve it was innervated by
Term
what is the cascade of action in the visual system?
Definition
Photons- Rhodopsin-Transducin-phosphodiesterase-cGMP-cationic inward ion channel- channel closes- ca2+ - synapses
Term
What is the cascade of action in olfaction
Definition
molecules- olfactory membrane receptors- G protein, adenaylate cyclase III- cAMP and ip3- cationic and anionic inward channels- open channel- ca2+ and protein kinases- impulses
Term
what is the cascade of action in Mechanoreception
Definition
displacemsnt- cationic inward ion channels open - myosin/actin motor - synapses
Term
Pain fibers project from primary sensory neurons to where
Definition
Ipsilatteral dorsal horn neurons
Term
Dorsal horn pain neurons project to where
Definition
Contralateral raphe nuclei and thalamus
Term
Raphe nuclei pain nerons project to where
Definition
Periaqueductal gray matter contrallaterally
Term
Periaqueductal gray matter pain neurons project to where?
Definition
the hypothalamus and somatosensory cortex
Term
where is the Periaqueductal gray located?
Definition
Next to the cerebral aqueduct in the midbrain
Term
where is the raphe nuclei located?
Definition
The ventromedial area of the mid medulla
Term
how do thermoreceptors and nociceptors differ in their threshold and adaptation to heat stimuli?
Definition
Thermoreceptors begin firing at a lower threshold and become saturated before nociceptors begin to fire. Nociceptors have a high threshold but have an even higher level of saturation.
Term
How do Adelta and C pain fibers differ
Definition
Adelta pain fibers are myelinated and provide the initial sharp response to pain. C fibers are unmyelinated and provide the slower burning sensations
Term
name some endogenous opioids
Definition
leucine-enkephalin
methionine- enkephalin
beta-endorphin
alpha- neoendorphin
dynorphins
Term
what is referred pain
Definition
referred pain is when visceral tissue pain is presented as pain on the surface of the body, sometimes not near the area of visceral tissue eg. left arm pain from heart attack
Term
how does the body cause pain in injured areas?
Definition
injury or tissue damage releases bradykinin and prostaglandins which sensitize and activate nociceptors. activation of nociceptors releases substance p. substance p acts on mast cells which releases histamine which excites nociceptors.
Term
what areas of the body are most sensitive to two point discrimination?
Definition
fingers, cheeks, nose lips, and toes. think of the sensory homunculus.
Term
what is hyperalgesia
Definition
hyperalgesia is the increased sensitivity to pain
Term
what are the optimal firing ranges in Celcius for cold receptors
Definition
20-40 degrees
Term
what are the optimal firing ranges for warm receptors
Definition
30-50 degrees
Term
what is the difference between the optic nerve and the optic tract
Definition
the optic nerve contains information from only one eye and is the path from eye to optic chiasm. the optic tract contains information from both eyes and goes from optic chiasm to striate cortex
Term
at what vibration frequencies would Pacinian corpuscle be activated
Definition
50-400 hz, but focused around 200
Term
Describe the four major mechanoreceptors by receptive field size and fast or slow adapting
Definition
Meissner corpuscle small field and fast
pacinian corpuscle large field and fast
Merkel cell small field and slow
Ruffini ending large field and slow
Term
what are the benefits of repeating substructures in the mamalian brain
Definition
sometimes they correspond to functional groups, such as in a1. other times we dont know yet.
Term
beginning from outside the eye and including optic structures, explain how light information enters the optic nerve
Definition
light passes through the cornea, the anterior chamber, then the lens, then the vitreous humor, then passes through the retina and contacts photoreceptors. photoreceptors transmit information through bipolar cells to retinal ganglion cells and then to the optic nerve
Term
what are the wavelengths that our rods and cones are most suited for
Definition
short cone- 375-475
rod- 400-580
middle cone- 430-625
long cone- 460-650
Term
What does scotopic mean
Definition
the area between the absolute threshold and the cones thresholds
Term
mesopic
Definition
the area between the cones threshold and rod saturation area
Term
photopic
Definition
the area where only cones are active up till maximum cone saturation/damage
Term
what is the function of the ciliary muscle
Definition
pulls on zonule fibers to adjust the thickness of the lens
Term
what is myopia?
Definition
nearsideness or a lengthening of the eye
Term
what is hyperopia?
Definition
farsidedness or a shortening of the ey
Term
what is emmertropia?
Definition
normal eye vision
Term
why do old people become farsighted?
Definition
as the lens ages, it becomes less elastic. this increases the minimum focal distance that can be achieved.
Term
what happens to the eye shape without visual stimuli
Definition
it becomes myopic
Term
what are the layers of the retina?
Definition
nerve fiber layer
ganglion cell layer
inner plexiform layer
inner nuclear layer
outer plexiform layer
outer nuclear layer
photo receptor outer segments
pigment epithelium
Term
what cell types are found in the inner plexiform layer
Definition
amacrine cells, and the axons and dendrites of bipolar and ganglion cells
Term
what cell types are found in the inner nuclear layer
Definition
amacrine cell bodies, bipolar cells and horizontal cell bodies
Term
what cell types are found in the outer plexiform layer
Definition
dendrites and axons of the horizontal, bipolar, rod, and cone cells
Term
what cell types are found in the outer nuclear layer
Definition
rod and cone
Term
where are cone cells most heavily concentrated?
Definition
0* off center at the foeva
Term
where are rod cells most heavily concentrated?
Definition
20 degrees off center
Term
how wide is the foeva?
Definition
200um
Term
what role does retinal play in the visual system?
Definition
all trans retinal is a component of rhodopsin membrane proteins. All trans retinal is metabolized into 11-cis-retinal. light isomerizes this back to all trans retinal. the eye regenerates this back to 11-cis-retinal in the course of several minutes.
Term
what role does cGMP play in the visual system?
Definition
cGMP gated channels close in the presence of light, hyperpolarizing the cell
Term
how do cone cells respond to varying intensities of light?
Definition
the brighter the light flash, the longer and more intense the membrane depolarization.
Term
why is it necessary to have more than one type of cell sensitive to different wavelengths?
Definition
with only one cell type, while differentiation of various wavelengths might be possible due to changing of average firing rate as the wavelength moved away from the best frequency, frequencies equidistant from the BF in opposite directions would appear identical.
Term
which layers of the Lateral geniculate nucleus are considered the magnocellular layers
Definition
layers 1 and 2
Term
which layers of the lateral geniculate nucleus are considered the parvocellular layers?
Definition
layers 3-6
Term
what is the optic chiasm
Definition
the optic chiasm is the place where visual information deccusates
Term
besides visual cortex, what structures process visual information?
Definition
hypothalamus- for regulation of circadian rhythms
pretectum- for reflex control of pupil and lens
superior colliculus- for orienting movements of head and eyes
Lateral geniculate nucleus- for visual information processing
Term
are fibers representing the inferior visual field located superior or inferior to those representing the superior visual field?
Definition
superior.
Term
What visual deficit would result from a lesion at the right optic nerve?
Definition
Right monocular blindness
Term
What visual deficit would result from a lesion at the optic chiasm
Definition
loss of peripheral vision
Term
What visual deficit would result from a lesion at the right optic tract?
Definition
left hemispatial neglect
Term
What visual deficit would result from a lesion at the right superior optic fibers?
Definition
lower left quadrispatial neglect
Term
why was that cat so happy?
Definition
cause they had it hooked up to a feeding tube and it just had to look at lights all day.
Term
If an electrode is pushed vertically through the layers of striate cortex, what activation would be expected at each layer?
Definition
layers 1-3,5,6 would show activation for whatever orientation they were specialized for. layer 4 would not show orientation specificity.
Term
if an election is placed horizontally through layers 1,2 or 3 in the striate cortex, what activation patterns would be expected?
Definition
as the electrode passes horizontally, the orientation specificity would change in a gradient.
Term
where does the information from both eyes first get processed together?
Definition
the striate cortex, as information is kept separate in the lateral geniculate nucleus.
Term
how is ocular dominance organized in the striate cortex?
Definition
neurons vary in their ocular dominance columns.
Term
what are some properties of x retinal ganglion cells?
Definition
medium size; many, most near foeva; medium conduction speed; project to lgn; linear spatial summation; movement sensitive, but not direction sensitive. color coded
Term
what are some properties of y retinal ganglion cells?
Definition
large cell size; few, most in periphery; fast conduction rate; project to superior colliculus and lgn; nonlinear spatial summation; very movement sensitive but not directionally sensitive; not color coded
Term
what are some properties of w retinal ganglion cells?
Definition
Vary in size; few in retina; vary in conduction rate; project to lgn and superior colliculus; mixed spatial summation. can be movement sensitive and directionally sensitive
Term
what is processed in the dorsal vision pathway?
Definition
spatial information
Term
what is processed in the ventral vision pathway?
Definition
object recognition
Term
describe the longest pathway visual information could take through the visual cortex
Definition
eye-
dorsal lgn
striate v1
v2
v3
v3a
v4
v5
to one of the streams
Term
what are some properties of simple striatal cortex cells as described by hubel and wiesel
Definition
respond to edges bars and slits all with preferred orientation of movement; dependent on location in receptive field
Term
what are some properties of complex striatal cortex cells as described by hubel and wiesel
Definition
respond to edges bars and slits all with prefered orientation of movement; independent of location within receptive field
Term
what are some properties of lower order hypercomplex striatal cortex cells as described by hubel and wiesel
Definition
respond to edges corners and angles of particular sizes; stimulus orientation and location dependant
Term
what are some properties of upper order hypercomplex striatal cortex cells as described by hubel and wiesel
Definition
respond to edges corners and angles of particular sizes; similar to lower order hypercomplex cells, but responded at two angles 90 degrees apart
Term
describe the anatomy of the human ear from the outside in.
Definition
the pinna is the external structure, the concha is the entrance to the external auditory meatus or ear canal. then sound hits the tympanic membrane which vibrates three bones called the malleus the incus and the stapes. these vibrate the basalar membrane inside the cochlea. other structures are also present. usually.
Term
how is the basilar membrane oriented?
Definition
high frequency sound is processed closest to the stapes, low frequency sound furthest.
Term
how do the tectorial membrane and the basilar membrane interact to activate hair cells?
Definition
the two have ofset pivot points, so the difference in position this creates bends hair cells and activates the associated neural pathways.
Term
how do hair cells activate from distortion?
Definition
the "hairs" of the cells have potassium channels that are tied to potassium channels on other hairs of the same cell. distortion opens all these channels resulting in depolarization, the opening of inward ca2+ channels and the resulting release of neurotransmitter vesicles
Term
do inner or outer hair cells send the majority of the information?
Definition
inner hair cells
Term
what do outer hair cells do?
Definition
outer hair cells can provide otoacoustical emissions via movement of the basilar membrane. it is believed this is done for frequency tuning via efferent neurons from the superior olivary complex
Term
what is the fastest primary like neuron found in the auditory nerve can fire?
Definition
3khz has been recorded
Term
what type of cells are present in the Dorsal cochlear nucleus and how do they fire??
Definition
pyramidal cells and they are pausers
Term
what type of neurons are present in the Anterior ventral cochlear nucleus and how do they fire?
Definition
spherical bushy cells- source like
Stellate cells- choppers
globular bushy cells- partially modified source like information
Term
what cells are found in the posterioventral cochlear nucleus and how do they fire?
Definition
octopus cells- on only
inhibitory multipolar cells- chopping
Term
describe the pathway of auditory information in the brain.
Definition
cochlear hair cells innervate the auditory nucleus which goes to the spiral gangion - dorsal cochlear nucleus- superior olive(ipsi and contrilateral) -inferior colliculus via the lateral lemniscus - medial geniculate nucleus of the thalams- A1
Term
where is spatial auditory information processed?
Definition
the medial superior olivary complex
Term
describe the neural pathway of the vestibular system
Definition
vestibular nucleus - ipsi and contrilateral thalamus - S1 layer 3a and to an area just behind s1
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