Principles of Sensory Systems Flashcards
3 common steps
require physical stimulus
must transform the stimulus into nerve impulse - sensory receptors in peripheral nervous system
evoke a response to the signal in the form of perception of sensation
sensory receptors
are cells, not just proteins
energy from environment —–> sensory transduction —–> electrochemical signals in sensory receptors
sensory receptors proteins
many receptor cells possess ion channels and GPCRs
specificity for sensory modalities
achieved by structure and position of the sensory receptor
vision, smell, balance, taste, taste ==== special senses
proprioception - understanding body position - how stretched muscle is
thermal senses
pain
touch
stimulus
receptor
location
hearing
mechanical
mechanoreceptor
cochlea
stimulus
receptor
location
balance
mechanical
mechanoreceptor
vestibular system
stimulus
receptor
location
vision
light
photoreceptor
retina
stimulus
receptor
location
touch
mechanical
mechanoreceptor
skin
stimulus
receptor
location
temperature
thermal
thermoreceptor
skin
stimulus
receptor
location
pain
mechanical, thermal, chemical
nocireceptor
skin, interal organs
stimulus
receptor
location
proprioception
mechanical
mechanoreceptor
muscles, joints, tendons
stimulus
receptor
location
olfaction
chemical
chemoreceptor
nasal cavity
stimulus
receptor
location
taste
chemical
chemoreceptors
tongue, pharynx, palate
pathway of stimulus
stimulus —- sensory receptor activated —- membrane permeability altered —- causes receptor potential to develop —- neurot is released onto afferent neuron terminal —- action potential generated in afferent neuron terminal —- propagtes to CNS
some dont have to release neurot as theyre neurons themselevs e.g. olfactory system
graded vs action potentials
muscle stretches = graded receptor potenital at dendritic portion of axon
if receptor potential is large enough, action potnital generated
more stretch = larger graded potential - reach action potential threshold
example of direct neuronal activation
olfactory receptors
graded = in cilia of dendrites soma = graded and action axon = action potential
sensory receptors can convey different types of info
modality
location
intensity
timing
stimulus modality is coded by labelled line code
labelled line code:
receptor is selective for one type of stimulus energy
axons of the receptor and associated afferent neuron acts as a modality specific line of communication
axons from these neurons make connections with specific areas in CNS
stimulating afferent neurons electrically leads to perception of the associated sensation
faulty labelled line code
synaesthesia
stimulus location
spatial arrangement of activated receptors within a sense organ give info about the stimulus
in somatic system, a receptive field is region of skin innverated by terminals of receptor neuron
in visual system, a receptive field of a photoreceptor is the region of visual field projected onto that receptor
stimulus intensity
totatl amount of stimulus energy delivered to receptor
lowest stimulus strength hat can be recieved = sensory threshold
intesnity is determined by response amplitude of receptor and therefore the firing frequency
stimulus timing
onset timing - when the stimulus energy is received by receptor and causes it to fire
stimulus duration - determined by adaptation rates of receptors
adaptation = in response to continuous stimuli, the firing rate of action potentials decreases
slowly adapting receptors
tonic receptors
respond to prolonged stimulation
rapidly adapting receptors
phasic receptors
respond at beginning and end of stimulus
