Neuro - Sensory systems Flashcards
what effects the rate of neurotransmitter release
stimulus strength
amplitude of generator potential
frequency of AP’s in afferent fibres
what are the 2 ways a signal can be transmitted
specialised sensory neurone
specialised epithelial receptor
what is a tonic receptor adapted for
continue to respond to respond for the duration of the stimulus
consistent rate of AP’s
slowly adapting
nociceptors
what are phasic receptors adapted for
burst of AP at onset and end of stimulus
some touch receptors
(feeling your watch only when you put in on and take it off)
what is a dermatome
region of skin innervated by the spinal nerve of a single nerve of a single dorsal root ganglion
where are somatic nerves segmented into
region of the periphery that they innervate
what is a receptive field
area of skin in which stimulation results in a change in rate of AP’s
what is the size of a receptive field dependant on
number of sensory receptor and size of branching of the sensory afferent
what does a higher density of sensory receptors equate to
smaller receptive fields
(your hands have a shit load of receptors so have small receptive fields)
what is two point discrimination
ability to distinguish 2 simultaneously applied stimulants as separate
spatial acuity
function of the dorsal column-medial lemniscal system
transmission pathway for touch to the body
1-3 order neurones transmit to somatosensory cortex
function of the trigeminothalamic system
transmission pathway for touch to the face
via the thalamus
feature of superficial receptors and name 2
high spatial acuity
meissner’s corpuscle
merkel’s disks
features of deep receptors and name 2
low spatial acuity
ruffini’s capsule
pacinian corpuscle
which receptors are phasic
meissner’s corpuscle
pacinian corpuscle
which receptors are tonic
ruffini’s capsule
merkel’s disk
function of the outer ear
amplifies sound pressure at 2-5kHz
localisation of sound source
function of the middle ear
important for amplifying the sound wave
why does the middle ear need to amplify sound
because the inner ear has an aqueous environment that dampens the sound waves
structure of the basilar membrane
snake that gets wider
narrow to wider to allow for distinction of different frequencies
how does the basilar membrane work
movements of vibrational energy causes the stereocilia in the cochlea to either undulate upwards or downwards
what do hair cells in the cochlea release
glutamate at the basolateral surface
function of the inner hair
afferent inputs
signals to CNS
function of outer hair
receives efferent signals from the CNS
modulates their activity
what is a ribbon
cytoskeletal specialisation
allows organisation of vesicles for faster neurotransmitter release
what are tip-links
link together stereocilia
co-ordinates their movement
distortion leads to open ion channels
what are stereocilia bathed in
endolymph - high in K+
what are base bathed in
bathed in perilymph - low in K+
how do outer hair cells respond to electrical signals
contract - depolarisation
expand - hyperpolarisation
what is a feature of auditory nerve cells
they are bipolar
where are auditory nerve cells located
spinal ganglion
where does information from both ear reach
both sides of the superior olive
where is the vestibular system located
inner ear
what is the vestibular system composed of
saccule
utricle
semi-circular cannals
what types of semi-circular cannals are there
superior
posterior
horizontal
what is the vestibular system attached to
the cochlea
they share fluids and ionic profile
what are the utricle and saccule classified as
otolith organs
where are vestibular hair cells located
utricle
saccule
ampullae of semi-circular cannals
what occurs at vestibular hair cells at rest
tonic release of neurotransmitters
β-waves
some ion channels still open
what is the macula
sensory epithelium
what overlays the stereocilia
otolithic membrane
what is the otoconia
crystal structure embedded in the otolithic membrane
makes it more dense
allows it to respond to gravity
what is the striola
hair cell positioning is mirrored, striola is in the middle
(short-long (striola) long-short)
what is the purpose of mirrored hair cell positioning
creates differential pattern of excitability
if head tilts one way - hairs will move from short to long on side and vice versa on the opposite side
causes difference in polarisation
what does the utricle and saccule detect
utricle - horizontal movements
saccule - vertical movements
what do semi-circular cannals detect and how
head rotation
endolymph flow displaces cupula
what is the vestribulo-ocular reflex
reflexively move your eyes in the opposite direction as your head
what is oscillopsia
caused by damage to the vestibular system
results in ‘bouncing vision’
