Jane Elyse Henkel PSB200 Exam 3 Fall 2011 L 11 Audition What are amplitude and loudness frequency and pitch Amplitude intensity of a sound wave height Loudness perception of intensity loudness does not increase with intensity Frequency number of compressions or waves per second Hz Pitch perception of frequency higher freq higher pitch humans 15 20 000 Hz Know the functions of the parts of the ear Know what part of the ear they are in outer middle inner are consist of Outer ear sound wave enters o Pinna auricle visible part of ear flesh cartilage funnels sound waves from outer to middle ear sound localization altering reflections of sound waves helps locate source direction of sound lobe where you get your ear pierced o External auditory canal canal to middle inner ear Middle ear sound wave is amplified o Tympanic membrane eardrum receives sound wave via auditory canal vibrates at same freq as sound waves that hit it attached to 3 tiny ear bones o Ossicles transform waves into stronger waves malleus hammer incus anvil stapes stirrup amplification of sound like levers by compressing force stronger waves go to the oval window Inner ear sound wave is transduced to electrical signals o Oval window membrane transmits waves through the viscous fluid of the inner ear receives vibrations from tiny ossicles of middle ear stirrup causes oval window to vibrate sets in motion all fluid in cochlea o Cochlea transduction snail shaped 3 long fluid filled canals b t basilar tectorial membranes in cochlea scala vestibule SV scala media SM scala tympani ST o Hair cells auditory receptors when displaced by vibrations in the fluid of the cochlea they excite the cells of the auditory nerve o Between basilar membrane tectorial membrane How does a hair cell work What ion enters the hair cell from the endolymph What leads to neurotransmitter release Potassium K enters the hair cell from the endolymph because of a concentration gradient Neurotransmitters are released because influx of K ions leads to depolarization of the receptor potential this then leads to the opening of VG Ca2 channels where neurotransmitters are released from the basal end of the cell NT s cross synaptic cleft gap bind trigger AP depolarizes stimulates auditory nerve brainstem auditory cortex What is the sequence of events from the sound wave entering the external auditory canal to the hair cell being stimulated 1 Pinna 2 Auditory canal 3 Tympanic membrane 4 Vibrates connects to 3 bones stirrup 5 Bones transmit vibrations to oval window membrane 6 Transform into stronger vibrations 7 Force moves viscous fluid 8 Auditory receptors hair cells between membranes are displaced by vibrations thereby opening ion channels in the membrane 9 Auditory nerve is excited by hair cells 1 Sound waves 2 Tympanic membrane 3 Ossicles 4 Oval window vibrates 5 Vibration into fluid cochlea 6 Hair cells displaced 7 Hair cells depolarized AP auditory nerve sent to brainstem What is the pathway that auditory information takes in the brain What aspect of processing does each of those regions do Auditory information in the brain auditory nerve cochlear nucleus pons localization midbrain inferior colliculus orienting and integration with visual thalamus sensory integration filter relay auditory cortex temporal lobe The cochlear nucleus pons ipsilateral ear only same side of the head All later stages have input originating from both ears Understand the term tonotopic and how it is relevant to the cochlea and the cortex Tonotopic cells in an area respond to tones of a particular frequency neurons are arranged in a gradient apex of basilar membrane responds to low frequency tones base of basilar membrane cells respond to high frequency tones Understand the terms place theory frequency matching Place theory each area along the basilar membrane has hair cells sensitive to only 1 specific frequency of sound wave best for high frequency sounds Frequency matching the basilar membrane vibrates in synchrony with sound and causes auditory nerve axons to produce APs at the same frequency How do we localize sounds Low freq phase difference high freq loudness difference Determining direction and distance of sound Depends on comparing responses of BOTH ears 3 cues 1 Sound shadow high freq 2 Time of arrival 3 Phase difference low freq What are 2 types of hearing loss What causes these conditions Conductive deafness middle ear prevented from transmitting sound waves properly to the cochlea o Causes disease infections tumorous bone growth o Treatment hearing aids amplify stimulus Nerve deafness damage to the cochlea hair cells or auditory nerve o Causes genetic birth issues viral infection autoimmune disease environmental repeated exposure to loud noises or drug intake o Treatment surgery L 12 Somatosensation What are 2 functions of skin Protection and sensory receptions Where are the receptors for somatosensation located Dermis below the epidermis How do the receptors differ from each other Simple bare neuron ending an elaborated neuron ending a bare ending surrounded by non neural Location in the dermis Understand the Pacinian corpuscle touch receptor how it works It detects sudden displacement or high frequency vibrations on skin o Onion like outer structure resists gradual or constant pressure o Inner structure neuron membrane a sudden or vibrating stimulus bends the membrane increased flow of Na ions triggers AP action potential Differentiate when general touch vs pain temperature information decussates Pain immediately decussates crosses o In the spinal cord information from one side of the body travels on ipsilateral same side for touch and contralateral opposite side for pain Touch decussates at the medulla o From medulla to cerebral cortex both touch and pain are represented on the contralateral side What is the pathway that somatosensory info takes to the brain Here you should be able to differentiate between general touch and pain temperature Information from touch receptors IN the head enters the CNS via the cranial nerves Trigeminal nerve Information from touch receptors BELOW the head enters through 31 spinal nerves to the brain cervical nerves 8 pairs thoracic nerves 12 lumbar 5 sacral 5 and coccygeal nerves 1 information entering the spinal cord travels in a well defined path touch and pain are distinct sensory touch information travels from cranial nerves or spinal nerves to the spinal cord thalamus somatosensory cortex in parietal lobe What neurotransmitters
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