2007 Sensory Physiology

Receptor proteins


  • there are 2 types of thermoreceptors:
    1. COLD: respond to temperatures between 5 and 35oC, AND greater than 45oC ("paradoxical cold")
    2. WARM: respond to temperatures between 30 and 45 oC
  • both types of thermoreceptor are rapidly adapting, i.e., they respond best when the temperature is changing
  • temperature detection is built into the structure of the channel

Cold receptor physiology

McKemy et al. (2002)
  • the actual process by which a deformation of the cell membrane causes the opening of a mechanotransduction channel is not known
  • proposed mechanisms include:
    1. direct activation due to lipid tension
    2. direct linkage via intracellular and extracellular proteins (see also the gating spring theory of auditory transduction)
    3. indirect activation via a second messenger system that activates the channel
  • TRP channels have been proposed as mammalian mechanoreceptors, but not conclusively established

Mechanoreceptor theories

Lin and Corey (2005)

  • TRPV1 is a known nociceptive channel
  • chemical stimuli that activate this channel include heat, protons, bradykinin and prostaglandins

TRPV1 structure

Cortright and Szallasi (2004)



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