Chapter 7 Flashcards
amplitude
intensity of a sound wave
loudness
related to amplitude; a sensation
frequency
number of compressions/second measured in Hz, most adults hear from 15-20,000 Hz
Pitch
related aspect of perception
pinna
outer ear structure of flesh and cartilage attached to the side of the head; alters reflections of sound waves to help us locate the source of a sound
tympanic membrane
ear drum, in the middle ear, vibrates with same frequency as the sound wave that strikes it; connected to three tiny bones (hammer, anvil and stirrup or malleus, incus and staples) that transmit vibrations to the oval window
oval window
membrane of the inner ear
hair cells
auditory receptors; lie between the basilar membrane of the cochlea on one side and the tectorial membrane on the other
cochlea
snail shaped structure of the inner ear that contains 3 long fluid filled tunnels: the scala vestibuli, scala media, and scala tympani
place theory
the basilar membrane resembles strings of a piano in that each area along the membrane is tuned to a specific frequency; each frequency activates hair cells at only one place along basilar membrane and nervous system distinguishes among frequencies based on which neurons respond; downfall: basilar membrane too tightly packed for this
frequency theory
basilar membrane vibrates in synchrony with a sound causing auditory nerve axons to produce action potentials at the same frequency (i.e. 50 Hz = 50 action potentials); downfall: refractory period is typically 1/1,000 second, so maximum firing rate of a neuron is about 100 Hz
current theory
modification of place and frequency; for low (under 100 Hz) - frequency theory; soft sounds activate fewer neurons than loud; volley theory up to 4000 Hz; place theory 4000+
volley theory
the auditory nerve as a whole produced volleys of impulses for sounds up to about 4000/sec
Primary auditory cortex (A1)
superior temporal cortex
conductive/middle ear deafness
deafness as a result of diseases, infections or tumourous bone growth that can prevent the middle ear from transmitting sound waves properly to the cochlea; can be temporary, can be corrected; normal cochlea and auditory nerve, and own voice is audible
nerve deafness/inner ear deafness
results from damage to the cochlea, the hair cells, or auditory nerve; can occur in any degree and may be confined to any part of the cochlea in which case someone hears certain frequencies and not others; can be inherited or developed (i.e. exposure to rubella, syph, toxins in womb, inadequate oxygen during birth, deficient thyroid, diseases incl. MS and meningitis, childhood reactions to certain drugs, loud noise exposure
tinnitus
frequent or constant ringing in the ears due to nerve damage
semicircular canals
in vestibular organ oriented in perpendicular planes, filled with jelly like substance and lined with hair cells, acceleration of the head pushes on hair cells - action potentials travel through part of CN 8 to brainstem and cerebellum
somatosensory system
sensation of body and its movements
Pacinian corpuscle
detects sudden displacements or high frequency vibrations on the skin - in normal conditions it insulates neuron against gradual or constant pressure
capsaicin
what makes peppers taste hot
dermatome
area of the body innervated by a spinal area - each overlaps 1/3 to 1/2 of the next dermodome
opioid mechanisms
systems that respond to opiate drugs and similar chemicals
peripheral aqueductal gray area
area of the midbrain where most binding sites for opiates are
endorphins
transmitters that attach to the same sites as morphine; endogenous morphines
gate theory
spinal cord neurons that receive messages from pain receptors also receive input from touch receptors and from axons descending from the brain, these other inputs close the “gates” for the pain messages at least in part by releasing endorphins
placebo
a drug or other procedure with no pharmacological effects, have little effect on most medical conditions but often relieve pain
labeled-line principle
each receptor would respond to a limited range of stimuli and the meaning would depend entirely on which neurons are active
across-fibre pattern principle
each receptor responds to a wider range of stimuli, and a given response by a given axon means little except in comparison to what other axons are doing
taste buds
taste results from stimulation of these taste receptors on the tongue; sloughed off and replaced, last 10-14 days; 50 + receptor cells in each; most along edge of tongue
pappilae
taste receptors are located in taste buds in papillae on the surface of the tongue; one papilla - 10 + taste buds
adaptation
temporary fatigue of receptors to a stimuli that is presented in excess
cross-adaptation
reduced response to one taste after exposure to another
nucleus of the tractus solitarius (NTS)
taste nerves project to the NTS, a structure in the medulla, where it branches out to pons, lateral hypothalamus, amygdala, ventral-posterior thalamus, and areas of the cerebral cortex
supertasters
people with the highest sensitivit to all tastes and mouth sensations (25+ papillae in 1/4 inch hole)
Olfaction
sense of smell
olfactory cells
neurons responsible for smell that line the olfactory epithelium in the rear of the nasal air passages; receptors located in celia (threadlike dendrites) that extend fom soma into mucous surface of the nasal passage
vomeronasal organ (VNO)
set of receptors located near but separate from the olfactory receptors, specialized to respond only to pheromones; each VNO receptor responds to only one pheromone in 1/100 billion concentration; VNO vestigial in humans
pheromones
chemicals released by an animal that affect the behaviour of other members of the same species
synesthesia
experience some people have in which stimulation of one sense evokes a perception of that sense and another one also, possibly genetic, possibly due to axons from one cortical area invading another
