Sensory coding and perception Flashcards
All receptors in the skin are low threshold except for which type of receptor?
Nociceptors
What fibres send impulses from hair follicle receptors?
A beta fibres
What fibres transmit sharp pain?
A delta
What fibres transmit dull aches?
C
What do Meissner corpuscles respond to?
Touch receptors - detect tapping or fluttering
What fibres send impulses from Meissner corpuscles
A beta
What do Merkel cells respond to?
Touch type stimulation
What fibres send impulses from Pacinian corpuscles?
A beta
What do Pacinian corpuscles respond to?
Vibration information (mechanical pressure)
What fibres send impulses from Ruffini corpuscles?
A beta
What to Ruffini corpuscles respond to?
Stretch
Where is the cell body of sensory neurones?
Dorsal root ganglion
How are signals transduced at Pacinian corpuscle?
Pressure changes alter the shape fo the corpuscle, altering shape of pressure sensitive Na+ channels, Na+ moves in and depolarises the membrane, voltage gated Na+ channels open
What is a generator potential?
Depolarisation due only to pressure sensitive Na+ channels
What is tonic firing Arte?
A constant rate
What are rapidly adapting receptors
Stop firing when a constant stimulation occurs
Which type of corpuscles are rapidly adapting?
Meissner and Pacinian
What are slow adapting receptors?
Fire faster as the stimulus increases
Which type of receptors are slow adapting receptors?
Ruffini and Merkel
What is a receptive field?
An area in which the nerve endings can send out signals and pick up information
What is lateral inhibition?
Ability of activated neurones to inhibit neighbours allowing more accurate localisation of pain
Describe convergence in the retina and describe why this is helpful
Axons of rods will converge so less need to be stimulated to see in black and white
What is the function of divergence of neurones?
Amplify a signal
Why do receptive fields that have been stimulated in the centre inhibit the lateral ones?
The ones hit in the centre fire more frequently so are stronger - will inhibit via interneurones
