• List the main classes of sensory receptor found in the body

Pacini’s corpuscle (touch receptor) 2mm long (largest mechanoreceptor)

found deep in the dermis detects high frequency vibration, works by A BETA fibres - present on glabrous & hairy skin rapidly acting due to slick viscous fluid between layers

receptor potential generation in a pancini corpuscle… compression anywhere in the region of the receptor causes a local Na flow which spreads along the nerve fibre, at the 1st node of ranvier this flow depolarises fiber membrane which sets off action potentials to the CNS

meissner’s corpuscle

encapsulated nerve endings similar to pacini’s but much smaller.they are present as stacked discs interspersed with nerve branch endings rapidly acting A BETA fibres but only present on glabrous skin types.

detects touch, flutter and low frequency vibration

found between dermal papille.

merkel disks

non-encapsulated nerve endings (looks like a tree with no leaves)

consists of specialised epithelial cell + nerve fibre

is located just under the skin surface in for example the finger tips - has good discrimination and detects static touch and light pressure

has A BETA fibres and is present on all skin types

slow adapting, low activation threshold

they work together with meissner’s corpuscles to determine texture

Ruffini corpuscles

encapsulated nerve ending