BIOL 125 - Lecture 11 Senses: Receptors

Tonic receptors

Receptors that respond at a constant rate

Phasic receptors

Detect stimulus or change in stimulus

Can undergo adaptation

Somatic receptors

Found within body wall

Respond to chemicals, temperature, pain, touch, proprioception, and pressure

Visceral receptors

Found within walls of viscera

Respond to chemicals, temperature, and pressure

Special senses

Senses that are only located in head in sense organs

Receptor distribution

where the receptor is found in the body

Stimulus origin

What tissues the receptors are found in

Modality of stimulus

What the receptor detects

Exteroceptors

Detect stimuli from external environment

Include cutaneous (skin or mucous membranes) and special senses (vision and hearing)

Interoceptors

Detect stimuli from inside of body

Taste and smell (chemoreceptors)

Walls of viscera - detect stretching, temperature, chemical changes, and pressure on or within organs

Proprioceptors

Associated with body movement

Muscles, tendons, and joints

detect body and limb movement, skeletal muscle contraction and stretch, and changes in joint capsule structure

Chemoreceptors

Detect chemicals dissolved in fluids

Thermoreceptors

Detect changes in temperature throughout body

Photoreceptors

Detect changes in light intensity, color, and movement of light

Mechanoreceptors

Detect physical deformation due to touch, pressure, vibration, and stretch

Baroreceptors

Detect pressure changes within body structures

Nociceptors

Detect tissue damage and pain

Temperature and pain receptors

Receptors with free nerve endings in epidermis that are unencapsulated

Lamellated corpuscles

Pressure receptors that are encapsulated

Tactile corpuscles

Tactile receptors that are encapsulated

Used in the 2pt discrimination test

Tactile disks

Tactile receptors that detect light touch

Unencapsulated

Root hair plexus

Tactile receptors that detect hair movement

Unencapsulated

Receptive Field

Location where sensitive ends of receptor cells are distributed. Size of receptive field location specific

Phantom pain

Sensory cell bodies from limb remain alive as part of dorsal spinal root – still provide sensation to CNS

Experienced with a missing limb

Referred Pain

When impulses from certain viscera are perceived as originating from elsewhere in the body