Sensory Receptors Flashcards
List the main classes of sensory receptor found in the body
Mechanoreceptors - tactile and position sensations
Thermoreceptors - detect heat and cold
Pain receptors - detect damage to the tissue
What is glabrous skin ?
Skin that doesn’t have hair on it
e.g. palm of hand / sole of foot
What is hairy skin ?
Skin that has hair on it
Touch from receptors in skin surface
Name some structures found in the dermis
Pacinian corpuscle
Meissners corpuscle
Ruffini’s ending
Hair follicle receptor
Free nerve endings
What do cutaneous mechanoreceptors respond to ?
Touch from receptors in skin surface
Pressure from receptors in deep tissue
Spray endings
Ruffini’s ending (specialised nerve endings)
Encapsulated endings
Pacinian corpuscles (receptor cells around nerve)
Muscle endings
Muscle spindles
Golgi tendon organs
Describe Pacini’s corpuscle
Largest mechanoreceptor in the skin (2mm long)
Onion like encapsulation of nerve ending
Found in deep layers of the dermis
Explain the structure of Pacini’s corpuscle
1st part is unmyelinated
2nd part is myelinated (as it leaves receptor cell)
ABeta fibres (quick) - glabrous & hairy skin
Function of Pacini’s corpuscle
Detects high frequency (40-500Hz) vibration
State some features of Pacini’s corpuscle
Rapidly adapting due to a slick viscous fluid between layers.
Has a low activation threshold (i.e. it is sensitive)
Describe Meissner’s corpuscle
Encapsulated nerve endings similar to Pacini’s but MUCH smaller
Found between dermal papillae
Explain the structure of Meissner’s corpuscle
Stacks of discs interspersed with nerve branch endings
ABeta Fibres (quick) - Glabrous skin types
Function of Meissner’s corpuscle
Detects touch, flutter and LOW frequency vibration
(2-40Hz)
State some features of Meissner’s corpuscle
Rapidly adapting - low activation threshold
(sensitive )
Describe Merkel’s discs
Non -encapsulated nerve endings
Explain the structure of Merkel’s discs
Consist of a specialised epithelial cell + nerve fibre
ABeta fibres - all skin types
Function of Merkel’s discs
Found just under the skin surface
e.g. fingertips : good discrimination :
- Detects static touch
- Light pressure
Work with Meissner’s corpuscles to help determine texture.
State some features of Merkel’s discs
Slowly adapting - low activation threshold (sensitive)
Describe hair follicles
Embedded in the skin
Function of hair follicles
Detect muscular movements of the hair (erector muscle) and external displacements of hair
What are hair follicles innervated by ?
Innervated by nerve endings wrapped around the follicle.
Describe Ruffini corpuscle
Encapsulated nerve endings
Function of Ruffini corpuscle
Responds to skin stretch and is located in the deeper layers of the skin as well as tendons and ligaments
Structure of Ruffini corpuscle
Nerve endings weave between collagen fibres which activate the nerve when they are pulled longitudinally.
ABeta fibres - all skin, but especially abundant in hands and fingers as well as sole of feet
Features of Ruffini corpuscle
Slow adapting - low threshold activation
(sensitive)
Skeletal muscle receptor types
Muscle spindles
Golgi Tendon organs
What are muscle spindles ?
Main proprioceptors that provide infrmaoin about the state of musculature.
Where are muscle spindles found ?
Muscle spindles lie within muscles in parallel with skeletal muscle fibres.
Particularly numerous in fine motor control muscles (e.g. eyes, hands)