sensory stimuli reaching the conscious level of perception
Vision, taste, smell, hearing, equilibrium/ posture
Sensory neurons project into thalamus for processing, relaying stimuli to
respective brain regions.
Receptors- classified according to stimuli type
Mechanoreceptors- ion channels; respond to pressure, vibrations, sound, stretch
Thermoreceptors- respond to temperature and chemicals.
For instance, capcasin gives
sensation of warmth for hot receptors and menthol gives sensation of a chill for cold
It depends on the temperature.
Chemoreceptors- respond to chemical ligands that bind to the receptor (Oxygen, Carbon
Dioxide, pH, glucose)
in the tongue, nose, brain, aorta
Photoreceptors- respond to light
Nociceptors- respond to noxious stimuli; pain
can be caused from very cold or very hot
In general, intensity of stimulus is coded by the number of receptors activated and in the
frequency of APs fired.
Types of Adaptive Receptors
Tonic Receptors- slowly adapt to a stimulus, or may not at all
Ex) Maintains state of contractility of skeletal muscle under a constant mechanical
Phasic Receptors- rapidly adapt to a continuous stimulus, prevents overwhelming the
brain with stimuli
Fire at initial stimulus or a change in stimulus intensity, but then stop when
stimulus becomes constant, fire again when stimulus is removed/ changes
Ex) hand in warm water or smell of perfume or the bathroom
2 Types of Receptors:
1) You have the “Fine touch, proprioception, and vibration” receptors
2) You also have the “Temperature, nociception, coarse touch receptors.
Types of Fibers: