Introduction to Sensory Physiology and Perception Flashcards
(43 cards)
what do receptors do?
detect the stimulus
types of receptors
photoreceptors, chemoreceptors, thermoreceptors, mechanoreceptors
examples of mechanoreceptors
pressure on skin, pressure in musculoskeletal system (proprioception), head movement (equilibirum), sound
samtosenroy system
inflammatory chemicals, temperature, pressure on skin, pressure in musculoskeletal system
what is the main somatosensory pathway?
primary afferent -> medulla –> thalamus –> cortex
what are somatosensory receptors also known as?
primary afferents
what are all-in-one receptors resilient to?
injury
whats different about other systems compared to somatosensory/olfactory?
receptors are separate cells. e.g. visual system, auditory and vestibular systems.
what is special about separate receptors?
they are delicate and irreplaceable e.g. photoreceptors
what are photoreceptors susceptible to?
light damage, genetic mutations, metabolic diseases, malnourishment
what are auditory hair cells susceptible to?
noise trauma, genetic mutations, ototoxicity, (chemotherapy agents, amino-glycoside antibiotics)
how can sensation be resorted?
if afferent survives, electronic system can stimulate sensation back. any acitivity in afferents will be interpreted as sensation so if rest of system is intact, function is restored
what is cochlear implant?
25 electrodes in ear that can stimulate afferents
how can gene therapy be used for photoreceptor restoration?
produce retinal cells to be photosensitive
what does transduction do?
produce electronic potentials
what does pressing on sensitive endings do?
produces receptor potentials that may give rise to action potentials
action potential threshold
Membrane potential at which action potentials are triggered.
This is a function of the vgNa+ channel and can be treated as a constant
‘activation’ threshold
Minimum stimulus strength that will depolarise a receptor enough to generate action potentials.
Sensory systems use receptors with a range of
different activation thresholds.
“Perceptual” threshold
Minimum stimulus strength that will generate enough action potentials to be detected.
Perceptual threshold is the bit we can most easily test in a
clinical environment.
is afferent signal a faithful copy of stimulus?
NO
spatial resolution is limited
due to receptive field
why cant you read braille with skin of arm?
receptive field sizes vary across the body
why can you read braille with skin of fingertips?
1mm receptive fields. smaller receptive fields means higher innervation density
spatial resolution is variable
the higher the innervation density, the more cortex needed to deal with the input
