BMS11004 - WEEK 7 WEDNESDAY Flashcards
name 3 common steps of sensory processing in all systems
physical stimulus transformed into nerve impulse by PNS, evoking response to signal in form of perception of sensation (CNS)
define sensory transduction
converting energy from environment into electrochemical signals in sensory receptors (both in forms of GP, AP)
explain structure of sensory receptor protein
contain ion channels and GPCRs common to many bodily functions
GPCR detect photons in retina, odorate mol in olfaction
name the 5 traditional senses, and other sense
vision, smell, taste, hearing, touch
balance, proprioception, thermal senses, pain
what is the stimulus and receptor for hearing
mechanical, mechanoreceptor
what is the stimulus and receptor for balance
mechanical, mechanoreceptor
what is the stimulus and receptor for vision
balance, photoreceptor
what is the stimulus and receptor for touch
mechanical, mechanoreceptor
what is the stimulus and receptor for temperature
thermal, thermoreceptor
what is the stimulus and receptor for pain
mechanical, thermal, chemical, nociceptor
what is the stimulus and receptor for proprioception
mechanical, mechanoreceptor
what is the stimulus and receptor for olfaction
chemical, chemoreceptor
what is the stimulus and receptor for taste
chemical, chemoreceptor
outline sensory receptor propagation
stimuli activate sensory receptor, alters membrane permeability and sensory cell develop receptor potential
NT released onto afferent neuron terminal (or skipped, and AP generated in afferent neuron terminal)
AP propagate to CNS, integrate information
compare AP, GP
GP increase in size in response to stimuli amplitude increase, but AP same size with threshold for activation
outline roles of AP, GP in muscles
small stretch opens membrane, ions move in, small depolarisation but not enough to trigger an AP (small GP dont cause AP)
if bigger GP, meet threshold, trigger AP
direct neuronal activation in olfactory receptors - explain process
olfactory receptor cell in olfactory epithelium has dendrites into mucus
enough odorant molecule bind cause ion influx, depolarisation, GP in dendrite, travel down neuron
large enough cause soma depolarisation, triggers AP (travels to olfactory bulb)
summarise sensory transductions
energy from environment converted into electrochem signal in sensory receptors
what 4 types of info can sensory receptors convey
modality, location, intensity, timing
what is labelled line code for stimulus modalities
receptor selective for specific types of stimulus energy
axons of receptor or associated afferent neuron act as modality specific communication line into CNS
what does stimulating afferent neurons in labelled line codes cause
perception of associated sensation, faults cause synaesthesia (perceive one stimulus as wrong, when fault in axonogensis, axons finding where they need to connect to)
what does spatial arrangement of activated receptors in sense organs mean
give info on stimulus
what are receptive fields
regions of skin which are innervated by terminals of receptor neuron, with receptive field size relevant to areas importance
explain size of receptive fields importance
larger stimulus activate more neuron
small object in hand activate few receptive fields
receptive field of photoreceptor is region of visual field projected onto it
outline stimulus intensity
total amount of stimulus energy delivered to receptors
outline sensory threshold
lowest stimulus strength that can be detected
what is stimuli intensity determined by
response amplitude of receptor, so firing frequency of afferent neurons
small stimuli activate small AP= less NT released
larger stimuli = bigger AP, more NT
what determines stimulus duration
adaption rate of receptors (in response to continuous stimuli, AP firing rates decreases)
what are slowly adapting receptors
tonic receptors that respond to prolonged stimulation
what are rapidly adapting receptors
phasic receptors that respond at beginning and end of stimulus
when initially sit down, sense it, then over time adapts so sensor stops sensing signal and passing it on
