lab 19: sensory receptors

Exteroreceptors

Respond to stimuli coming from external environment

Sensory receptors in dermis, photoreceptors in eyes, and olfactory receptors in nose are

Exteroreceptors

Interoreceptors

Monitor internal body conditions like osmotic conditions, blood pressure, muscle and joint movements, etc.

Proprioreceptors

Inform the brain of joint activity

In free nerve endings dendrites are

Bare

In encapsulated nerve endings dendrites are

Surrounded by a connective tissue capsule

Nocireceptors

In dermis and basal layer of epidermis, free nerve endings, detect pain as a result of tissue damage

Merkel disc

At junction of epidermis and dermis, free nerve endings, detect touch and pressure

Meissner’s corpuscles

In papillary region of dermis, encapsulated, detect fine touch and pressure

Thermoreceptors

In dermis, free nerve endings, cold receptors detect temperature between 10-40 C, heat receptors detect temperature between 32-49 C

Hair root complexes

Wrapped around hair follicle, free nerve endings, detect hair movement

Ruffini’s corpuscles

In dermis, encapsulated, detect stretching

Pacinian corpuscle

Deep in dermis, encapsulated, detect crude touch and pressure

Two point discrimination

Ability to distinguish between two points as two separate points being touched simultaneously

Two points felt

Each touch is a different receptor, two sensory neurons innervating two separate receptor fields

One point felt

Both touch points stimulate the same receptor

Fast adapting receptors

Pacinian corpuscles and Meissner’s corpuscles

Slow adapting receptors

Nocireceptors and Ruffini’s corpuscles