principles of sensory systems Flashcards
what are 3 common steps for conservation of sensory processing?
- physical stimulus
- transform stimulus into nerve impulses (by sensory receptors in PNS)
- perception of sensation (CNS)
structure of sensory receptors?
receptors can be cells not just proteins
- sensory receptor cells also have sensory receptors proteins (e.g. ion channels and G-protein coupled receptors)
what are the sensory modalities (types)?
vision, smell, taste, hearing, touch, balance, thermal senses, pain, proprioceptors
what is the stimulus, receptor and location for hearing?
stimulus - mechanical
receptor - mechanoreceptor
location - inner ear - cochlea
what is the stimulus, receptor and location for balance?
stimulus - mechanical
receptor - mechanoreceptor
location - inner ear
what is the stimulus, receptor and location for vision?
stimulus - light
receptor - photoreceptor
location - retina
what is the stimulus, receptor and location for touch?
stimulus - mechanical
receptor - mechanoreceptor
location - skin
what is the stimulus, receptor and location for temperature?
stimulus - thermal
receptor - thermoreceptor
location - skin
what is the stimulus, receptor and location for pain?
stimulus - mechanical, thermal, chemical
receptor - nociceptor
location - skin, internal organs
what is the stimulus, receptor and location for proprioception?
stimulus - mechanical
receptor - mechanoreceptor
location - muscles, tendons, joints
what is the stimulus, receptor and location for olfaction?
stimulus - chemical
receptor - chemoreceptor
location - nasal cavity
what is the stimulus, receptor and location for taste?
stimulus - chemical
receptor - chemoreceptor
location - tongue, pharynx, palate, epiglottis
general process of stimulus to CNS?
- stimulus activates sensory receptor protein
- change in membrane permeability
- graded receptor potential develops (voltage change)
- neurotransmitter released onto afferent neuron terminals
- action potential generates in afferent neuron which propagates to CNS where info is integrated
(some neurons skip neurotransmitter, they can detect stimulus and generate action potential)
different between graded vs action potential
- graded receptor potentials increase in size in response to increases in stimulus amplitude
- action potentials always same size but have threshold for activation
what type of information can sensory receptors convey?
- modality
- location
- intensity
- timing
what is sensory transduction?
converting energy from the environment into electrochemical signals in sensory receptors
how is stimulus modality encoded in CNS?
labelled line code:
- axons of afferent neuron is a modality specific line of communication
- axons made connections with specific areas in CNS
what happens if labelled line code is faulty?
synesthesia - stimulation of one sensory pathway leads to experiences in another pathway
what is a receptive field?
region of sensory space where stimulus can influence activity of sensory receptor (conveys location of stimulus)
what is a receptive field in the somatic system (touch)?
region of skin innervated by the terminals of the receptor neuron
how do action potentials code increase in graded receptor potential?
increased frequency of action potentials
what is sensory threshold?
lowest stimulus strength that can be detected (e.g. quietist sound you can hear)
what are phasic receptors?
rapidly adapting receptors
- respond at the beginning and end of a stimulus
what are tonic receptors?
slowly adapting receptors
- respond to prolonged stimulation
definition of adaptation
decrease of firing potential in response to continuous stimulus
what determines stimulus duration?
adaptation rates of receptors
what determines onset timing?
when the stimulus is received by the receptor and causes it to fire
