Senses and Perception Flashcards
what is tactile input
this is the type of mechanical stimulation on the skin
what is the quality of tactile input
the type of touch
what is the magnitude of tactile input
this is how big the input is
what is the duration of tactile input
this is how long and how often the stimulus lasts
where does most bodily innervation go as the first point of entry
the spinal cord
how do we convert a stimulus into an electrical signal
through modality specific sensory receptors
how is information transmitted faithfully to the central nervous system
through modality specific sensory pathways
wat is the first cell involved in the sensation pathway
the sensory neuron
what do sensory neurons do
they relay information from the periphery into the central nervous system
what is the morphology of the sensory neuron
pseudounipolar structure
describe the structure of the sensory neuron
cell body with two axons
first branch is in the periphery and innervates the skin, and a second brnach which projects into the central nervous system
what is found at the end of the peripheral branch of sensory neurons
receptor endings
what is found at the central terminal of sensory neurons
synaptic vesicles, which allow for synaptic release to recruit target neurons in the sensory pathway
list the events of a general stimulus on primary sensory receptors
- stimulus
- receptor endings activated
- action potential generated
- relayed centrally
- neurotransmitter released at central terminal
- recruitment of post synaptic targets
how are stimulus properties coded
according to quality, intensity, duration and location
what are the main stimulus types
mechanical
thermal
noxious
chemical
light
describe the stimulus and receptor for the sensation of touch
mechanical stimulus
mechanoreceptor
describe the stimulus and receptor for the sensation of temperature
thermal stimulus
thermoreceptor
describe the stimulus and receptor for the sensation of pain
noxious stimulus, nociceptor
describe the stimulus and receptor for the sensation of taste and smell
chemical stimulus, chemoreceptor
describe the stimulus and receptor for the sensation of vision
light stimulus
photoreceptor
which receptors are found on free nerve endings
nociceptors
what are the different mechanoreceptors found in the skin
meissners corpuscle
merkel disk
hair follicle receptor
pacinian corpuscle
ruffini ending
what is this
meissners corpuscle
mechanoreceptor in the skin
what is this
merkels disc
a mechanoreceptor found in the skin
what is this
hair follicle receptor
mechanoreceptor found in the skin
what is this
pacinian corpuscle
a mechanoreceptor found in the skin
what is this
ruffini ending
mechanoreceptor found in the skin
what features are found in all sensory neurons
cluster of peripheral nerve branches with its own receptor endings
what is a receptive field
this is the distribution of receptor endings found in each neuron
do receptive fields remain separate
they often overlap to allow for two point discrimination
how large are receptive fields in the periphery
small
how large are receptive fields in the trunk of the body
very large
what is two point discrimination
this is the ability to discern two separate mechanical stimuli
it is a measure of spatial resolution and an indication of the size of the receptive field
describe the temporal sequence of stimulus transduction
- stimulus
- change in receptor membrane permeability
- influx of cations
- depolarisation on the receptor potential
- action potential
what is the resting membrane potential on most cells
-70mV
what are the two subtypes of receptor
ionotropic and g protein coupled
describe the kinetics and modalities of ionotropic receptors
fast kinetics
mechanoreceptors and chemoreceptors
describe the kinetics of g protein coupled receptors
slow kinetics and chemoreceptors
describe signal transduction of ionotropic mechanoreceptors
- there is a lipid bilayer that has been interrupted by an ion channel
- the ion channel is tethered to the membrane by fibrils on the intracellular aspect of the membrane
- when inactive, the channel is closed
- when mechanical stimulus is applied, the deformation of the cell membrane pulls on the underlying fibrils which pulls the fibres away to open the channel
- potassium leaves and sodium enters
describe the signal transduction in ionotropic chemoreceptors
- ion channel is too narrow in the inactive state
- extracellular surface has ligand binding receptor sites
- this becomes active when the ligands bind
- conformational change allows the pore to open
- sodium and potassium can cross over
describe signal transduction in g protein coupled receptors
receptor is more complex as there are many proteins linekd to it.
the ligand binding site changes conformation to cause a response on the ion channel
when inactive, the channel is closed. the specific ligand will bind to the receptor, cause an intracellular signalling cascade, and then the channel can open.
so it is a lot slower because the pathway is more complex than in ionotropic receptors
what is the stimulus property for type of receptor
quality
what is the stimulus property for action potential frequency
magnitude or intensity
what is the stimulus property for number of neurons activated
magnitude or intensity
what is the stimulus property for duration of action potential firing
duration or timing
what is the stimulus property for receptive field
location
what does the quality of the receptor depend on
type of receptor
what does the magnitude of the stimulus depend on
the action potential frequency and the number of neurons that has been activated
what does the duration of the stimulus depend on
duration of the action potentia firing