41. Sensory Receptors

yaboiemil's version from 2016-01-14 14:10


1. Sensory receptors can receive and perceive information.
2. Sensory receptors can be basic Free Nerve Endings (terminal branch of a nerve ending between 2 cells,
where they end is the innervation area, mostly detect pain)
3. Sensory receptors can be more complex Sensory Corpuscules (sensory nerve fibre is encapsulated
in differentiated tissue, could be sensory cells to help detect specific modalities)

Types of Sensory Receptor

Be sure to learn at least these, so that no one can catch you off-guard and make you look foolish.


Question Answer
MechanoreceptorsReceptor that responds to mechanical stimuli (touch/sound)
ThermoreceptorsReceptor of heat/temperature change
ChemoreceptorsReceptor of Chemical signals/molecules
PhotoreceptorsReceptor of Light


Question Answer
TeloreceptorsDetect stimuli from distant sources
ExteroreceptorsDetect stimuli that directly make contact with receptor
ProprioreceptorsInform the body of passive movement of limbs
InterorreceptorsIn internal organs, initiate pain to maintain stable environment


4. Receptor cells have common features: Outer segment (finger-like) AND Inner Segment (filled with mitochondria).
5. When stimulus occurs, (e.g. an ion channel is opened) cations flood in, causing a Receptor Potential.
6. The influx of Cations (like K+) enter outer segment, flow to inner segment.

General Definitions


Question Answer
ModalityA particular form of sensory perception (e.g. smell, taste, sight)
Adequate StimulusThe type of energy a sensory receptor responds to
Projection LawIf a nerve is irritated at a point from periphery>brain, the sensation is projected to the relevant receptor
AdaptationIf a stimulus intensity is maintained for a long period, irritability decreases
Receptor Potentiala local change in the resting membrane potential, the triggers the action potential
Weber-Fechner Lawproposed relationship between magnitude of a physical stimulus and intensity/strength that people feel

Weber - Fechner Law



Question Answer
IrSensation Intensity
K1Proportionality Constant
IsImpulse Intensity



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