Sensory Transduction Flashcards
how do we hear - brief overview
sound > vibration of air > vibrate the eardrum, the malleus, the incus, the stapes > vibration spreads to cochlea > vibration of air is converted to movement/vibration of fluids in the cochlea > vibration in the cochlea is captured by hair cells > transduction > perceived in the auditory cortex
what is transduction
physical vibration is transduced to neural energy
what makes up the middle ear
malleus
incus
stapes
what does the stapes connect to
the oval window of the cochlea
what does the inner ear contain
cochlea - part of auditory system
labyrinth - part of vestibular system
what are the 3 fluid filled cavities of the cochlea
scala vestibuli
scala media
scala tympani
what separates the cavities of the cochlea
Reissner’s membrane separates s.v. from s.m
Basilar membrane separates s.m. from s.t
what plays a role in the cochlea in transduction
organ of Corti hair cells, basilar membrane to tectorial membrane
where do the s.t. and s.v meet
helicotrema
what does the s.t. and s.v. connect with respectively
s. t. = oval window
s. v. = round window
what fluid is present in the cavities
endolymph - scala media
perilymph - scala vestibuli and typmani (continous with the two cavities)
what do the hair cells do in the ear
auditory receptors with sterocilia
synapse on bipolar neurons with cell body in the spiral ganglion
where are the hair cells located
between basilar membrane and reticular lamina
how do the hair cells contribute to transduction
- tectorial membrane vibrates
- hair cells’ cilia bend
- depending on how they bend, the hair cells release neurotransmitter
- the neurotransmitters released in the hair cell are captured in nerve fibers.
- neural energy sent to the brain
what is odd about hair cell cell channels
K+ current is inwards due to endolymph
what is the function of the vestibular system
Provides information concerning gravity, rotation and acceleration
allows for:
- gaze & postural stability
- sense of orientation
- detection of linear & angular acceleration
how does the vestibular system work
Head angular acceleration (semicircular canals)
- Head rotation.
Head linear acceleration (saccule and utricle)
- Translational motion.
- Gravity (and by extension head tilt).
what does the movement of cells towards and away the crystals cause
towards = depolarisation
away = hyperpolarisation
what is the structure of the semicircular canals
3 fluid-filled canals, right angles to each other
1 for each major plane
what fluid is in the semicircular canals
endolymph
what are the otolith organs
saccule and utricle
what are the 3 major vestibular reflexes
Vestibulo-ocular reflex
Vestibulo-colic reflex
Vestibular-spinal reflex
what does the vestibulo-ocular reflex do
keep the eyes still in space when the head moves.
what does the Vestibulo-colic reflex do
keeps the head still in space – or on a level plane when you walk.
what does Vestibular-spinal reflex do
adjusts posture for rapid changes in position.
what is the cupula and where is it located
structure in the vestibular system, providing sense of spatial orientation
located within the ampullae of each of the three semicircular canals
what is the overview of how vision works
1 - pattern of the object must fall on the vision receptors (rods and cones in the retina)»_space; accommodation
2 - amount of light entering the eye must be regulated
3 - energy from the waves of photons must be transduced into electrical signals
4 - brain must receive and interpret the signals
direct pathway for signal transmission
photoreceptors»_space; bipolar cells»_space; ganglion cells
what is the function of photoreceptors
Converts electromagnetic radiation to neural signals
what are the 2 types of photoreceptors
rods and cones
what are the 4 main regions of a photoreceptor
Outer segment
Inner segment
Cell body
Synaptic terminal
what is the basis for phototransduction
1 - Vertebrate Photoreceptors have a depolarized rmp
2 - With light exposure, Vm hyperpolarizes
3 - A cGMP-gated Na+ channel that is open in the dark and closes in the light
4 - change in Na+ with light is the signal that enables the brain to perceive objects in the visual field
when is the dark-current channel open and closed
opens in the dark
closes in the light
what opens the dark-current
cGMP
what vitamin is needed for sight
vitamin A
why is the dark-current channel important
Keeps photoreceptor Vm more positive than most neurons
→ Steady release of neurotransmitter
what do rods and cones see
Rods – seeing in dim light
Cones – seeing in normal daylight
what are features of rods
achromatic peripheral retina high convergence high light sensitivity low visual acuity
what are features of cones
chromatic central retina (fovea) low convergence low light sensitivity high visual acuity
what is the function of horizontal cells
Receive input from photoreceptors and project to other photoreceptors and bipolar cells
what is the function of amacrine cells
Receive input from bipolar cells and project to ganglion cells, bipolar cells, and other amacrine cells
