Sensory Modalities• General Senses:

1. Somatic (Exteroceptors)a. Touchb. Pressurec. Temperatured. Proprioceptione. Pain

2. Visceral (Interoceptors)a. Painb. Pressure

Examples of sensory receptors and their relationship with 1st order neurons

Sensory Modalities

• Special Senses

a. Smell or Olfaction

b. Taste or Gustation

c. Sight or Vision

d. Sound or Auditory

e. Balance or Equilibrium

The Process of Sensations

1. Stimulation of a sensory receptor2. Transduction of the stimulus

Conversion of the stimulus into a graded potential

3. Generation of an impulseConversion of a graded potential into

an action potential at a trigger zone and propagation to CNS

4. Integration of sensory input

Classification of General Sensory Receptors

Type of Sense Receptor Type Stimulus

Touch Mechanoreceptor Compression

Pressure Mechanoreceptor Compression

Temperature Thermoreceptors Temperature

Proprioception Mechanoreceptor Compression

Pain Nociceptors Irritation

Summary of Tactile Sensory Receptors

Receptor Sensations Adaptation

Meissner Corpuscles

Touch, pressure, slow vibrations

Rapid

Hair root plexuses Touch Rapid

Merkel’s disc Touch and pressure Slow

Ruffini corpuscles Stretching of skin Slow

Free nerve ending Itch/tickle Both

Pacinian Corpuscles

Pressure, fast vibrations, tickling

Rapid

Summary of Sensory Receptors

Receptor Sensations Adaptation

Free nerve ending Temperature Rapid

Free nerve ending Pain Slow

Muscle spindles Muscle length Slow

Tendon organs Muscle tension Slow

Joint Kinesthetic receptors

Joint position and movement

Rapid

Somatic Receptors of the Skin

Classification of Special Sensory Receptors

Type of Sense Receptor Type Stimulus

Smell Chemoreceptor Binding of Molecules

Taste Chemoreceptor Binding of Molecules

Sight Photoreceptors Light

Sound Mechanoreceptor Sound waves

Balance Mechanoreceptor Movement of head

Olfactory epithelium, Olfactory receptors, and Olfactory Nerves

Relationship of Gustatory receptors in Taste Buds to tongue papillae