L.2.2 Flashcards
what are primary sensory nerve fibres
nerve fibres that transmit different sensory modalities (ex: chemical, mechanical or thermal)
What are the features of large sensory nerve fibres
- conduct signals more quickly
- faster signal transmission
Why do large primary sensory nerve fibres conduct signals faster
- greater diameter (less resistance)
- more myelination
What are examples of large primary sensory nerve fibres
proprioception and touch fibres
What are features of small sensory nerve fibres
- conducts signals more slowly
- slower signal transmission
Why do small sensory nerve fibre conduct signals slower
- they have a smaller diameter (more resistance)
- little to myelination
What is the function of tactile receptors close to the surface of the skin
- important for detecting light touch and texture
Name 2 tactile receptors that are close to the surface of the skin
- Merkel’s disk
- Meissner’s corpuscle
What is the function of deeper tactile receptors
specialised for sensing deeper pressure and skin stretching
What are the differences in receptive field size between tactile receptors
- close to surface: small receptive fields
- deep: large receptive fields
What does the size of the receptor field mean
- small receptor field = smaller area of skin = allows more precision
- larger receptor field = larger skin area = no precision and allows gross movement
What are rapid adapting receptors
- respond strongly at the start of stimulus and continue even if the stimulus is gone
- good for detecting changes in stimuli
What are the slowly adapting receptors
- continue to fire as long as the stimulus is present
- good for detecting continuous pressure or stretch
How does mechanical transduction work
- touch is transduced by mechanically sensitive ion channels
- channels open to the deformation of the cell membrane by skin/receptors
- this leads to action potential
What are the 2 ways in which sensory information is coded by primary sensory neurons
- rate coding
- temporal coding
What is rate coding
- frequency of action potentials
How does rate coding code sensory information
- stronger stimulus = higher frequency of APs = higher rate of coding
What is temporal coding in sensory information processing?
- Temporal coding refers to the timing of action potentials
- helps to know when a stimulus occurs
How does the CNS interpret sensory information?
based on the rate (frequency) and timing (temporal coding) of action potentials
What is spatial resolution
the ability to distinguish between two close touches.
How is spatial distribution measured
using the 2-point discrimination test.
What is the significance of the 2-point discrimination test?
- can be used to assess nerve damage
- if nerve damage = can’t separate even at large distances
Why is the density of tactile receptors greater on the hand and face
it allows for better spatial resolution
How does the spatial distribution of tactile receptors vary across the body?
Some areas of the body have more tactile receptors than others, which affects sensitivity and spatial resolution