Sensation and Sensory Receptors

Sensation

Conscious or subconscious awareness of external or internal stimuli

Perception

Conscious awareness and interpretation of sensations, performed mainly by the cerebral cortex

General Senses

Tactile, thermal, pain, proprioceptive, and visceral sensations

Special Senses

Smell, taste, vision, hearing, and equilibrium sensations

Step 1

Stimulation of a sensory receptor

Step 2

Transduction of the stimulus, converting stimulus into a graded potential

Step 3

Generation of impulses, propagation from CNS to PNS

Step 4

Integration of sensory input

Free Nerve Endings

Sensory receptor that are bare dendrites with no visible structural specializations, stimulate first-order neurons

Free Nerve Ending Sensations

Detect pain, thermal, tickle, and itch

Encapsulated Nerve Endings

Sensory receptors whose dendrites are covered, stimulate first-order neurons

Encapsulated Nerve Ending Sensations

Detect touch, pressure, and vibration

Separate Cells

Sensory receptor that causes a release of a neurotransmitter that stimulates first-order neurons

Separate Cell Sensations

Detect special senses

Exteroceptors

Sensory receptors located at or near the external surface of the body, detect hearing, vision, smell, taste, thermal, and pain

Interoceptors

Sensory receptors located internally, detect sensations not usually consciously perceived

Proprioceptors

Sensory receptors that provide information about body position, muscle tension, and position/movement of joints

Mechanoreceptors

Sensory receptors that detect mechanical pressure or stretching

Thermoreceptors

Sensory receptors that detect change in temperature

Nociceptors

Sensory receptors that detect physical or chemical damage/pain to tissues

Photoreceptors

Sensory receptors that detect light in the retina

Chemoreceptors

Sensory receptors that detect chemical sensations such as smell, taste, and body fluids

Osmoreceptors

Sensory receptors that detect osmotic pressure of body fluids

Adaptation

A decrease in amplitude of a generator/receptor potential due to a maintained, constant stimulus