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54 Cards in this Set

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