Senses And Perceptions 1 Flashcards
What things need to be considered during mechanical stimulation of the skin
What type of touch? Quality
How big is it? Magnitude, intensity
How long? How often? Duration/timing
Where? Location
How do we convert a stimulus into an electrical signal (action potential)?
Modality specific sensory receptors
How is the information transmitted faithfully
Modality specific sensory pathways
What receptor does a mechanical stimulus activate
Mechanoreceptors, sensation is touch
What receptor does a thermal stimulus activate
Thermoreceptor
What receptor does a noxious stimulus activate
Nociceptor
What receptor does a chemical stimulus activate
Chemoreceptor
What receptor does a licht stimulus activate
Photoreceptors
What sensation does a mechanical stimulus provide
Touch
What sensation does a thermal stimulus produce
Temperature
What sensation does a noxious stimulus provide
Pain
What sensation does a chemical stimulus provide
Taste, smell
What sensation does licht stimulus provide
Sight, vision
What are receptive field properties
Each sensory neuron has a cluster of peripheral nerve branches, each with receptor endings, the distribution of these receptor endings defines a neurons receptive field
Describe the position of the receptor fields
All the receptor fields overlap, there are many in the body
The receptor fields overlapping means every area on the body will have some form of receptor ending
Describe the sizes of receptor fields
They will vary in size in different regions in the body, they are small in the periphery and large on the trunk
What is two point discrimination
The ability to discern two separate mechanical stimuli
- a measure of spatial resolution
- an indicator of receptive field size
What is the sequence of signal transduction
Stimulus > change in receptor membrane permeability > influx of cations > depolarisation - receptor potential > action potential (AP)
What is the difference between ionotropic receptors and G protein coupled receptors
Ionotropic has fast kinetics and G protein coupled has slow kinetics
Ionotropic - mechanoreceptor and chemoreceptor
G protein coupled - chemoreceptor
Describe how ionotropic mecahnoreceptors are opened
On the inside of the cells membrane, in the inactive state it is closed, force changes the formation of the cell membrane, as a consequence of the mechanical force it pulls the fibrils away and the pore will open,this allows the transfer of both sodium and potassium ions
Describe how the ionotropic chemoreceptors are opened
The channels become active when a ligand binds to the channel and opens it
Describe how a G protein coupled chemoreceptor opens
A serious of proteins is linked to the G protein receptor when a ligand binds to the receptor this induces a protein cascade which will open the channels
What is the coding for quality
Type of receptor
What is the stimulus for AP frequency, number neurons activated
Magnitude/intensity
What is the coding for duration/timing
Duration of AP firing
What is the coding for the location
Receptive field
What is the sensory homunculus
The body map in the brain
The receptor field sizings at different parts of the body
What is the stimulus location
Coded by receptive field activated
