Cutaneous Receptors and Mechanoreceptors

Flashcards cover the main cutaneous receptors (Meissner, Merkel, Pacinian, Ruffini), their locations, adaptation rates, and the types of sensations they convey, along with Free Nerve Endings and general somatosensory pathways.

What are the four principal cutaneous mechanoreceptors responsible for touch, and their adapting types?

Meissner corpuscle (RA1), Merkel disk receptor (SA1), Pacinian corpuscle (RA2), Ruffini ending (SA2).

Where are Meissner corpuscles and Merkel disks primarily located in the skin?

Meissner and Merkel receptors are in the superficial layers of the skin at the base of the epidermis; Meissner near the papillary ridges, Merkel around the center of the ridges.

What is the adaptation rate of Meissner corpuscles?

Rapidly adapting (RA1).

What is the adaptation rate of Merkel disk receptors?

Slowly adapting (SA1).

What is the adaptation rate of Pacinian corpuscles?

Rapidly adapting (RA2).

What is the adaptation rate of Ruffini endings?

Slowly adapting (SA2).

Which receptor is primarily associated with sensing fine touch, flutter, and movement?

Meissner corpuscle.

Which receptor is associated with touch and pressure, located in deep skin?

Merkel complex (Merkel cell + Merkel disk).

Which receptor is football-shaped and responds to vibration?

Pacinian corpuscle.

Which receptor is deep in the dermis and detects skin stretch?

Ruffini ending.

What is the structure and location of Pacinian corpuscles?

Football-shaped encapsulated receptor in the dermis (deeper tissue), with a central afferent nerve fiber and onion-like layers; outer fluid is displaced when force is applied.

What is the structure of Meissner corpuscles?

Encapsulated stack of flattened epithelial cells in glabrous skin; when force is applied, the cells slide past each other, triggering the sensory axon.

What are Free Nerve Endings and what do they detect?

Unencapsulated endings located throughout the body; detect chemical responses that produce pain and temperature changes.

Which receptors contribute to the sensation of touch vs. vibration vs. skin stretch?

Meissner and Merkel (touch); Pacinian (vibration); Ruffini (skin stretch).

Which receptors innervate multiple receptor organs vs a single receptor organ, and what is the pattern?

RA1 and SA1 fibers branch to innervate several receptor organs; RA2 and SA2 fibers innervate only one receptor organ.

Which information travels via different anatomical pathways in the somatosensory system?

Touch and proprioception vs. temperature and pain use different pathways.

What modalities are carried by cutaneous receptors as described in the notes?

Touch (including fine touch, flutter, movement), pressure, vibration, skin stretch, pain, and temperature.

What does the somatosensory system convey about objects and body position?

Information about objects in the external environment through touch and about the position and movement of body parts (proprioception), plus temperature and pain.

Describe the relationship between receptor adaptation and duration of sensation.

Rapidly adapting receptors convey brief, dynamic changes; slowly adapting receptors convey sustained sensations.