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184 Cards in this Set
- Front
- Back
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Afferent sensory system
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necessary for setting up movement
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Chemoreceptors
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pH, oxygen, organic molecules
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Mechanoreceptors
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vibration, acceleration, sound
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Photoreceptors
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light
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Thermoreceptors
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temperature
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nocireceptors
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tissue damage, pain
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Muller's Law
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Different types of receptors for different stimuli
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Primary Sensory R- Simple
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free nerve endings, unmyelinated (slow), saves space
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Primary Sensory R- Complex
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myelinated axon, enclosed nerve ending, layers of connective tissue
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Primary Sensory R- Special
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specialized R, synapes specialized neuron, myelinated axon
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Sensory transduction converts stimuli into graded potentials
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-receptor potential
-generator potential |
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4 stimulus properties
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stimulus modality (type), location, intensity and duration
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Labeled line coding
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direction association between receptor and sensation
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Receptive field
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specific area where sensory receptor is most sensitive to stimulation
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Convergence of inputs
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Onto single sensory neuron - enhances neuron's sensitivity but reduces spatial resolution
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Sensory receptive field
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varies in size and overlap frequency
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Lateral Inhibition (Stim Location)
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enhances contrast b/w the stimulus and its surroundings, facilitating its perception and localization
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Stimulus Intensity
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1) Population Coding
2)Freq. Coding |
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Population Coding
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number of receptors activated
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Frequency Coding
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frequency of APs
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Stimulus Duration
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1) Tonic Rs
2) Phasic Rs |
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Tonic Rs
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Fires for duration of stimulus, slow adaption
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Phasic Rs
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Rapidly adapt to stimulus and turn off, fire once more when stimulus turns off
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Primary Sensory Neurons
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Take info from receptors to secondary sensory neurons in CNS
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Secondary Sensory Neurons in CNS
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neurons that cross midline, cross over at different locations, synpase on tertiary sensory neurons in thalamus
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Tertiary Sensory Neurons
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project to cerebral cortex
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Olfactory sensory neurons
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project directly to cerebral cortex, not routed through thalamus
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Spinal Cord
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White and Gray Matter
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Gray Matter
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H shaped middle, neuron cell bodies
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White Matter
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nerve fibres and axons, covered with fatty myelin
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Spinal Nerves
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divided into two branches called roots
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Ventral Root
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carries info from the CNS to the muscles and organs/glands
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Dorsal Root
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Of each spinal nerve is specialized to carry incoming sensory information
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Dorsal Root Ganglia
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contains cell bodies of sensory neurons
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Ascending Tracts (white matter)
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take sensory info to brain, occupy dorsal and external lateral portions of the spinal cord (dorsal column and spinothalamic tract)
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Descending Tracts (white matter)
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carry commands to effector organs, occupy ventral and internal lateral portions of the cord (lateral & ventral corticospinal tracts)
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Fine touch, pressure neurons
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cross over at medulla
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coarse touch, tickle, itch
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cross over immediately upon reaching SC
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pain, temperature
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cross over immediately upon reaching SC
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Hemi-transect to spinal cord?
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Will lose fine touch on that side and coarse touch/pain on other side
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Dorsal Column
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large myelinated axons that carry
fine touch information, cross over at the medulla. |
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Spinothalamic Tracts
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small unmyelinated axons that
carry pain, temperature, and coarse touch, cross over at the level of the spine |
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Dermatones
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31 segments that the spinal cord is divided into, each receives input from receptors in a localized area
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Cerebral Cortex
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four lobes with distinct functions
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Parietal Lobe
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somatic senses, primary somatic sensory cortex
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Homunculus
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map of sensory receptive fields organized in somatosensory cortex
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taste
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gustatory cortex (insula) beneath frontal and parietal cortex
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Temporal Lobe
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hearing
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Smell
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olfactory cortex, medial temporal lobe
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Vision
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Occipital Lobe
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Cerebral Lateralization
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functional areas in the two hemispheres are not symmetrical
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Right Brain
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Spatial and musical skills
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Left Brain
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language and verbal skills
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Wernicke's Area
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audiovisual
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Broca'a Area
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Speech and writing
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Sound waves
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alternating waves of air pressure with periods of compression and rarefraction
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Pitch
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frequency of sound waves (Hertz)
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Loudness
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Sound intensity (db) - logarithmic scale
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Noise levels above 100db
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damage to ear
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Sound Transmission- Sound waves
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strike tympanic membrane (eardrum) and become vibrations
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Sound wave E
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tranferred to 3 bones of middle ear (malleus, incus and stapes), which vibrate
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Vibrations of stapes' front plate against oval window converted
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to fluid waves within vestibular duct
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Fluid Waves
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push on membranes of cochlear duct, thereby activating sensory hair cell Rs
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Fluid Waves E
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transfer across cochlear duct and into tympanic duct and dissipated at round window
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Activated hair cells within cochlear duct
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create APs in sensory neurons of the cochlear nerve
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Inside of snail end of cochlea
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apex
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Cochlear duct contains
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endolymph (high K+)
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Vestibular and tympanic ducts contain
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perilymph, similar to plasma
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Tectoral membrane
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deformed by fluid waves, pushes on specialized hair cell receptors
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Coding Sound Loudness
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as sound increases, frequency of APs increase
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Coding Pitch
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coded spatially, by location of hair cell receptor along basilar membrane
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Cochlea's hair cell receptors
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tonotopically organized
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Low frequency processed
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at apex
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mid frequency processed
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at mid basilar membrane
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high frequency processed
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at base
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Spatial Coding of Pitch
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preserved in primary auditory cortex in the temporal lobe
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Signals travel from primary sensory neurons travel cochlear nerve and reach
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cochlear nucleus in brainstem
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After traveling through cochlear nucleus, signals relayed to
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thalamus in the brain
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After traveling through thalamus in the brain (sound) signals
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to primary auditory cortex in the temporal lobe
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Coding Sound Location
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time delay b/w two ears (interaural time difference) and intensity difference b/w two ears
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Sound delay and intensity converge on
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inferior colliculus
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Vestibular apparatus
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responds to both rotational and linear changes in body's position relative to space
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Semicircular Canals
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3, at right angles to at other, sense rotational acceleration
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Otolith Organs (utricle and saccule)
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2, sense linear acceleration
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Utricle and Saccule
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filled with endolymph
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Cristae
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sensory Rs for rotation acceleration, located at base of ear semicircular canal in enlarged chamber (ampulla)
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Crista
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contains gelatinous mass (cupula)
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When pushed by endolymph, cupula
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bends embedded cilia of each hair cell receptor
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Heard starts to turn
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endolymph cannot keep up (because of inertia)
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Drag of endolymph on cupula
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bends cupula and embedded hair cells in direction opposite of head
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Semicircular Canals
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do not respond when head is motionless or moving at constant speed
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Saccule
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senses verticals forces
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Utricle
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sense horizontal forces
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Sensory Rs in saccule and utricle
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macculae
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Maccula
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Consists of gelatinous mass in which small crystals of calcium carbonate and cilia of hair cell Rs are embedded
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Head moves up or down, forwards or backwards
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crystalline otoliths slide, pull gelatinous membrane which bends hair cells, membrane depolarizes, primary sensory neurons increase their firing rate
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Neural signals from vestibular apparatus
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travel along vestibuloccochlear nerve
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vestibuloccochlear nerve signals transmitted to
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vestibular nuclei in brain stem
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From the vestibular nuclei in brain stem, neural signals travel to
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cerebellum
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At cerebellum, neural signals from ear and combined with
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prioreceptive inputs
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In space
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semicircular canals still function, otolith organs can still perceive linear acceleration, but absence of force gravity on saccule
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Sea sick
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ears say movement, eyes stay still, body assumes virus, expels stomach contents
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Visible Light
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400-750nm
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Eye
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Fluid-filled sphere with 3 tissue layers
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Outerlayer tissue layer of eye
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schlera and cornea
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Middle tissue layer of eye
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iris, ciliary body and choroid
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inner tissue layer of eye
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retina
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Light travels through
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cornera, aqueous humour of the anterior chamber, pupil, lens, vitreous humor
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Iris
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contains musculature controlling pupil size, modulates amount of light that enters eyes
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Ciliary body
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encircles lens, controls shape of lens
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Ciliary body and cornea
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help focus image on retina
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Cataracts
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proteins in lens denatured, causing clouding
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Aqueous Humor
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clear, watery liquid produced by ciliary body in posterior chamber, it regulates the intraocular pressure
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Vitreous humor
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thick, gelatinous substance
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Choroid
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capillary bed, supplies oxygenation and metabolic sustenance to cells in the retina
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Parasympathetic control of pupil
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circular constrictor muscles decrease pupil size
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Sympathetic control of pupil
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radial (dilator) muscles increase pupil size
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Accomodation
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Changing of lens' refractive power
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lens changes shape through
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inelastic fibres (zonulas)
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ciliary muscles relax
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zonulas tight, lens thinner
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ciliary muscles contract
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zonulas loose, lens rounded
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Myopia
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image focused in front of retina
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hyperopia
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image focused behind retina
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Hyperopia
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convex lens
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myopia
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concave lens
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Near point of accomodation
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closest distance at which your lens can focus on objects
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Fovea
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central region of retina where visual acuity is best
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Retina
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light strikes photoRs only after passing though sensory neurons except at fovea
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Colours
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seen by ratios of amount cones stimulated
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Peripheral Rods
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Large spacing (lower density), converge on large ganglion cell, increase sensitivity but decrease accuracy (pinpoint)
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Foveal cones
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high density, one of one ratio with ganglion cells
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Rods
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achromatic night vision, light levels are low
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Cones
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high acuity colour, day, light levels higher
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Light hits photoRs,conformational change causes
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hyperpolaization
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Vm of photoRs in dark
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-40mV
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Hyperpolarization of photoRs
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cause hyperpolarizationand depolarization in bipolar and ganglion cells
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Graded potentials
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modulate discharge rate of ganglion cells
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ON bipolar & ganglion cells
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detect increase in luminance
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OFF bipolar & ganglion cells
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detect decrease in luminance
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The receptive fields of ganglion cells
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centre-surround organization
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Stimulation of field around receptive fields of ganglion cells
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elicit opposite responses
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Centre-surround organization
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In rows, good at detecting lines
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Visual system
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detects local differences in intensity, not absolute amounts of light
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Monocular vision
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one eye vision
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Binocular vision
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overlap of vision from both eyes
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Nerve fiber from nasal half of each retina cross over at
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optic chiasm
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Optic tracts
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allow right and left visual fields to separately reach the left and right hemispheres
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Optic tracts
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project to thalamus
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thalamus
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projects to primary visual cortex in the occipital lobe
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entire visual field
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precisely mapped onto primary visual cortex, visuotopic organization
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Ventral Stream
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Vision for perception
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Dorsal Stream
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Vision for action
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Natural Stimuli
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multi-faceted, usually activate multiple R types
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Free nerve endings (somatosensory Rs)
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around hair roots and under skin surface
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Merkel Receptors
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skin pressure
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merkel receptors
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enlarged nerve endings in superficial skin layers
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Meisner's Corpuscle
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Flutter/stroking
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Meisner's Corpuscle
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encapsulated in connective tissue in superficial skin layers
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Ruffini corpuscle
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skin stretch
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Ruffini corpuscle
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enlarged nerve endings in deep skin layers
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Pacinian corpuscle
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vibration
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Pacinian corpuscle
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encapsulated in connective tissue in deep skin layers
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Touch-pressure Receptors
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not uniformly or identically distributed
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Aβ fibers
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large, myelinated, fast fibers (30 – 70 m/s)
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Aβ fibers
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fine touch; pressure; proprioception
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Aδ fibers
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small, myelinated, slow fibers (12 – 30 m/s)
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Aδ fibers
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cold; fast & sharp pain; coarse touch
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C fibers
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small, unmyelinated, very slow fibers (0.5 – 2 m/s)
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C fibers
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temperature; slow & dull pain; coarse touch
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Thermoreceptors
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free nerve endings with small receptive fields (~1mm) scattered across the body
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Thermoreceptors
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sensitive to (fast) changes in temperature, not absolute temperature
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Thermoreceptors
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adapt only between 20-40 degrees
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Stimuli outside of thermoreceptor range activate
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nocireceptors
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Pain
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consequence of tissue damage
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Nocireceptors
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free nerve endings sensitive to a variety of molecules released with tissue damage
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Fast and sharp pain
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transmitted via Aδ fibers from the
activation of thermal nociceptors (>45° or <5° C) or mechanical nociceptors (intense pressure). |
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Slow & dull pain
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transmitted via C fibers from the
activation of polymodal nociceptors (high-intensity mechanical, thermal or chemical stimuli) |
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Fast & sharp pain
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good stimulus localization
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Slow & dull pain
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poor stimulus localization
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Somatic pain
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well localized, constant pain that
is described as sharp, aching, throbbing, or gnawing. |
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Visceral pain
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poorly localized and often felt in
somatic areas distant from the painful stimulus. |
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Referred pain
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due to the
convergence of nociceptive fibers onto a single ascending tract. |
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Gating Theory of Pain Modulation
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perception of pain is subject to modulation.
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gating theory of pain modulation,
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inhibition of the
ascending pain pathway can be enhanced by the activation of non-nociceptive somatic Aβ fibers |
