principles of sensory systems Flashcards
what are the 3 steps with the Conservation of sensory processing across systems
-Require a physical stimulus
-Must transform the stimulus into nerve impulses- Sensory receptors in the peripheral nervous system
-Evoke a response to the signal in the form of perception of sensation- Central nervous system
what’s sensory transduction
-energy from the environment -> electrochemical signals in sensory receptors
-transformation of the signal from the electrical signal
what are sensory receptor proteins
-Many sensory receptor cells possess ion channels and G-protein coupled receptors that are common to many bodily functions
-can be G protein channel receptors and ionotropic
-can be specialised
how is Specificity for sensory modalities achieved
-by the structure and position of the sensory receptor
whats proprioception
-proprioceptors are parts of the muscle fibres and detect how stretched your muscle fibres are
-so you know where your body is in space
modality with its stimulus, receptor and location
-hearing : stimulus=mechancal , receptor=mechanoreceptors, location=inner ear- cochlear
-balance: stimulus=mechanical , receptor=mechanoreceptor, location= inner ear
-vision : stimulus= light , receptor= photoreceptor, location= retina
-touch : stimulus= mechanical , receptor= mechanoreceptor, location= skin
-temperature : stimulus= thermal , receptor= thermoreceptor , location= skin
-pain : stimulus= mechanical, thermal and chemical , receptor= nociceptor, location= skin and internal organs
-proprioception : stimulus= mechanical, receptor= mechanoreceptor, location= muscles, tendons and joints
-olfaction : stimulus= chemical, receptor= chemoreceptors , location= nasal cavity
-taste : stimulus= chemical, receptor= chemoreceptor, location= tongue, pharynx, palate, epiglottis
how does a stimulus lead to the formation being integrated by the CNS
-stimulus -> sensory receptor is activated -> Membrane permeability is altered in the sensory cell -> A receptor potential develops in the sensory cell -> Neurotransmitter is released onto afferent neuron terminals -> An action potential is generated in the
afferent neuron terminal -> The action potential propagates to the CNS -> Information is integrated by
the CNS
- can go stright from A receptor potential develops in the sensory cell -> An action potential is
generated in the afferent neuron terminal
graded receptor potential vs action potential
-Graded receptor potentials increase in size in response to increases in stimulus amplitude
-Action potentials are always the same size, but have a threshold for activation
whats an Example of direct neuronal activation
-olfactory receptors
-Ion influx causes membrane depolarisation and a graded receptor potential develops in a cilium
-Large enough receptor potentials cause depolarisation in the cell soma, triggering action potentials that travel to the olfactory bulb
taste receptors
-Ion influx causes membrane depolarisation and a graded receptor potential develops
-Initiates synaptic vesicle fusion with membrane and neurotransmitter release
-Neurotransmitter binds to postsynaptic receptors, generating an EPSP in the dendrite of the afferent neuron
-Large enough EPSPs generate action potentials
what type of information can sensory receptors convey
-Modality
-Location
-Intensity
-Timing
whats stimulus modality coded by
-the labelled line code
-The receptor is selective for one type of stimulus energy
-The axons of the receptor/associated afferent neuron acts as a modality specific line of communication
-Axons from these neurons make connections with specific areas in the CNS
-Stimulating afferent neurons electrically leads to perception of the associated sensation
-The labelled line code is faulty in synaesthesia
whats the stimulus location
-Spatial arrangement of activated receptors within a sense organ gives information about the stimulus
-In the somatic system, a receptive field is the region of skin innervated by the terminals of the receptor neuron
-In the visual system, a receptive field of a photoreceptor is the region of the visual field projected onto that receptor
whats stimulus intensity
-Intensity is the total amount of stimulus energy delivered to the receptor
-The lowest stimulus strength that can be detected is known as the sensory threshold
-Intensity is determined by the response amplitude of the receptor and thus the firing frequency of the afferent neurons
whats stimulus timing
-Onset timing is determined by when the stimulus energy is received by the receptor and causes it to fire
-Stimulus duration is 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 the beginning and end of a stimulus
