Receptors: Definition and classification - QS Study
QS Study

Receptors are a part of the neuron or specialized cells which can generate the action potential in the neuron. It is an organ or cell able to respond to light, heat, or other external stimulus and transmit a signal to a sensory nerve. Receptors are often located in the sense organs, such as the ear, eye, and skin. Each organ has receptors sensitive to particular kinds of stimulus.

Classification

(A) According to sensitivity to a particular font of energy:

Mechanoreceptors: Detect mechanical changes eg.,

  • Muscle spindle,
  • Merkel’s dise.

Thermoreceptors: Detect change of temperature eg.,

  • End buts of Krause (cold)
  • End-organ of Ruffini (Heat).

Nociceptors: Detect physical or chemical damage of tissue, eg., Free nerve ending.

Electromagnetic receptors: Detect light eg. Rods and cones of the retina (vision).

Chemoreceptors: Detect changes in chemical composition – eg., a gustatory cell of taste blue (taste).

Fig: Receptors classification

(B) According to the type of sensation:

(a) General sensory receptors: For general sense –

Cutaneous receptors (exteroceptors): free nerve ending;

Deep receptors:

  • Interceptors: Baroreceptors
  • Proprioceptors: Muscle spindles.

Visceral receptors: Free nerve ending.

(b) Special sensory receptors: For vision, hearing smell and test.

Telereceptors: For distant senses –

  • Rods and cones of the retina (vision)
  • Hair cell of organ of cacti (Hearing)

Chemical sense receptors:

  • Taste bud-For taste
  • Olfactory cells-for smell

(c) According to structure –

  • Non-encapsulated: Free nerve ending.
  • Encapsulated: Meissner’s corpuscles.