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54 Cards in this Set
- Front
- Back
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Two somatosensory pathways
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Pain and temperature
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Spinothalamic pathway crosses in the what and ascends to what
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1. Spinal segment of entry
2. Contralateral somatosensory cortex |
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Somatosensory pathways to the brain keep
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The different stimulus types seperate
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Somatotopy
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Body surface is mapped onto the somatosensory cortex
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In the developmental requirement for tough, individual receptor fires if the stimulation is in the
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Receptive field and supplies sufficient energy of the right kind
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Adaptation
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Response to a stimulus decreases with time in the continued presence of a stimulus. Can be slow or rapid
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Hair follicle receptors
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Free nerve endings wrapped around follicle
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To what stimlulus does the skin need to respond?
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1. Contact with foreign objects
2. Changes in temperature 3. Near damage and damage |
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Somatosensory recepeptors respond to
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Narrow range of mechanical energy in the receptors receptive field
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The need for pain
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1. short latency
2. long latency |
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Tissue injury causes
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Release of chemicals which sensitize or activate receptors
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Neurons release what as pain mediators
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Substance P, a neurotransmitter which stimulates mast cells and blood vessels. results in vasolidation=swelling of blood capillaries
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Adds to pain stimulus
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Histamine released from mast cells and bradykinin released from blood vessels
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Causes depolarization
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Histamine and bradykinin
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Capsaicin causes release of
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Substance P from nociceptors in mouth
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Gate theory
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Gentle pressure on a fresh injury may help reduce pain
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An example of capsaicin
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Shingles
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Sound Pressure Level
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Intensity
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Wavelength
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Distance between disturbances
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Waveform
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Shape of motion pattern
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Spectrum
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What frequencies are present
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For sound, velocity is about
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1100 ft/sec
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The audible spectrum frequency range
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16-20 hz to 20,000 hz
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In transformer action, pressure =
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Force/Area
ex: thumbtack |
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Fluid displacement result in
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A traveling wave along the basilar membrane
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Tonotopic organization
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The location of the maximum of the traveling wave is determined by the stimulus frequency in the inner ear
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The organ of corti sits on
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The basilar membrance
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Stereocilia
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Another name for inner hair cells
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Displacement of the basilar membrane towards the scala vestibuli results in
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Depolarization of the OHC-decreasing its length
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Displacement in the opposite direction towards the scala tympani produces
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Hyperpolarization, an increase in OHC length
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Audible intensity range, threshold of discomfort
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0 db to > 120 db
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Tectorial membrane sits on top of
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Organ of corti
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Scala vestibuli and scala tympani contain this fluid
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Perilymph (cerebral spinal fluid)
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Endolymph is very high in ? and low in ?
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K+, N+
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Transduction by hair cells
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Sound: basilar membrane upward, reticular lamina up and stereocilia bends outward
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Phase locking
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Consisten firing of cell at same sound wave phase for low frequency sounds
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Ascending auditory system follow both
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Contralateral and ipsalateral pathways
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Minimal pathway from cochlea to cortex
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Cochlear nucleus to superior olivary complex to inferior colliculus to medial geniculate to cortex
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Psychoacoustics
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Scientific study of human perception of sound
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Weber
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Founder of pschophysics
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Fechners law
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The magnitude of a sensation is related to the stimulus intensity
S = K log I |
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Absolute threshold
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Basic threshold-minimum amount of energy needed to become aware of stimulus
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Differential (discrimination) threshold
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The minimum difference needed to detect a change in the stimulus
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Doubling of sones
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10 db
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Scaling of sensations
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Assigning a judgement to the percieved magnitude of a stimulus
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Magnitude of perception
loudness, pitch |
1. sones
2. mels |
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The case of the missing fundamental or residue
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The basic effect is to obtain a pitch for a frequency that is not present in the sound
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Best threshold for hearing
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0 db
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Consonant sounds have very little sound power but
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A great influence on meaning
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Magnitude of sensation
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Related to stimulus intensity
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Middle ear is ventilated by
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The eustachian tube
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Middle ear transformer works like a thumbtack,
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Boosts pressure 27-30 db because of change in area of TM to stapes
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Transduction in inner ear is due to
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Hair cells and overlying membrane
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Sensory nerves of outer hair cells are
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Unmeylinated and small
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