Module 10: Figure nociception
Transduction and modulation of pain stimuli.
The nerve endings of sensory neurons have a number of ion channels that respond to a variety of pain stimuli. Noxious cold and heat are detected by transient receptor potential channels TRPM8 and TRPV1 respectively. The TRPV1 channels are also sensitive to the H+ released at sites of tissue injury during inflammatory responses (Module 10: Figure inflammatory soup). ATP acts on P2X3 channels. The sensitivity of these different ion channels can be modulated by a variety of signalling mechanisms, as described in the text.