46 Sensory Receptors,

Neuronal Circuits forProcessing Information

Dr. A.R. Jamshidi Fard2011

Types of Sensory Receptors

• (1) Mechanoreceptors

• (2) Thermoreceptors

• (3) Nociceptors

• (4) Electromagnetic receptors

• (5) Chemoreceptors,

I. MechanoreceptorsSkin tactile sensibilities (epidermis and dermis)Free nerve endingsExpanded tip endingsMerkel’s discsPlus several other variantsSpray endingsRuffini’s endingsEncapsulated endingsMeissner’s corpusclesKrause’s corpusclesHair end-organsDeep tissue sensibilitiesFree nerve endingsExpanded tip endingsSpray endingsRuffini’s endingsPacinian corpusclesMuscle endingsMuscle spindlesGolgi tendon receptorsHearing; Sound receptors of cochleaEquilibrium; Vestibular receptorsArterial pressureBaroreceptors of carotid sinuses and aorta

II. ThermoreceptorsColdCold receptorsWarmthWarm receptors

III. NociceptorsPainFree nerve endingsIV. Electromagnetic receptorsVisionRodsCones

V. ChemoreceptorsTasteReceptors of taste budsSmellReceptors of olfactory epitheliumArterial oxygenReceptors of aortic and carotid bodiesOsmolalityNeurons in or near supraoptic nucleiBlood CO2Receptors in or on surface of medulla and in aortic andcarotid bodiesBlood glucose, amino acids, fatty acidsReceptors in hypothalamus

Receptor Potential of the Pacinian Corpuscle

An Example of Receptor Function

Adaptation of Receptors

Viscoelastic structure

Accommodation

Relation Between Stimulus Intensity and the Receptor Potential.

Amplitude of Receptor PotentialAll or None Law?

Toni or Phasic Receptors

Classification of

Nerve Fibers

Spatial Summation Temporal Summation

Processing of Signals in Neuronal Pools

Divergence)Amplification(

Convergence

Reverberatory Circuits

CPGsCentralPatternGenerator

Prolongation of a Signal by aNeuronal Pool “Afterdischarge”

Reverberatory Circuits

CPGs Central Pattern Generator

Instability and Stability of Neuronal Circuits

1 -Synaptic Fatigue2 -Downregulation or Upregulation of Synaptic Receptors