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Sensory System
Published in Peter Kam, Ian Power, Michael J. Cousins, Philip J. Siddal, Principles of Physiology for the Anaesthetist, 2020
Peter Kam, Ian Power, Michael J. Cousins, Philip J. Siddal
The sensory receptors as described earlier transduce the stimulus into electrical energy (receptor potential). The sensory modalities (touch, pressure, temperature, pain and proprioception (joint and muscle position sense) are transmitted in different ascending pathways (tracts) that are located in specific areas of the spinal cord white matter and terminate in specific areas of the brain. Each pathway consists of four neurons: First-order neurons are the primary afferents neurons that receive the transduced signals and send them to the central nervous system. Cell bodies of the primary afferent neurons are located in the dorsal root or spinal cord ganglia.Second-order neurons (located in the spinal cord or brain stem), which receive signals from one or more primary afferent neurons, transmit them to the thalamus. Axons of second-order neurons cross (decussate) the midline in the relay nuclei in the spinal cord before they ascend to the contralateral thalamus.In third-order neurons, located in the relay nuclei of the thalamus, the signals ascend to the cerebral cortex.For fourth-order neurons, located in the sensory cortex, the information received results in conscious perception of the stimulus.
Basic Thermal Physiology: What Processes Lead to the Temperature Distribution on the Skin Surface
Published in Kurt Ammer, Francis Ring, The Thermal Human Body, 2019
The electrophysiological characteristics of thermoreceptors are established since the 1980s, but the molecular basis of cold and warm receptors was elucidated in the beginning of the 21st century by the detection of transient receptor potentials (TRP) [7].
Cochlear mechanisms and processes
Published in Stanley A. Gelfand, Hearing, 2017
Several electrical potentials may be recorded from various parts of the cochlea and its environs. References have already been made to the cochlear microphonic, which is one of these, and to the general conceptualization of the action of sensory receptors. Resting potentials are the positive and negative direct current (DC) polarizations of the various tissues and their surrounding fluids. Receptor potentials are electrical responses from a receptor cell (e.g., a cochlear hair cell) that result when the cell is stimulated (interested students will find a comprehensive review in Russell, 2008). These may involve alternating current (AC) or DC. Note that the presence of a receptor potential does not necessarily mean that the nervous system is aware of the stimulus; it reflects the fact that the hair cell itself has responded. It is the transmission of a chemical mediator across the synapse and the resulting neural firing that indicates that the signal has now activated the nervous system. We may conceive of these potentials in terms of whether they are derived from a single cell or from many cells. Compound potentials include the contributions of many cells at various distances from the electrode, and may include responses to different phases of the same stimulus (or to different stimuli) at different times and in different ways. Thus, the electrode “sees” a much different picture than it would if it were recording from a single cell.
Monitoring trends in lacrimator exposures using the National Poison Data System: 2000–2021
Published in Clinical Toxicology, 2023
Daniel Nogee, Colin Therriault, Michael Yeh, Stephanie Kieszak, Amy Schnall, Kaitlyn Brown, Alvin Bronstein, Arthur Chang, Erik Svendsen
When used, lacrimators are often employed as an aerosol to cover large areas but can also be a handheld spray for focused application [7]. These agents have irritant effects that can incapacitate an individual by acting on transient receptor potential (TRP) channels. Transient receptor potential channels are located throughout the human body in nociceptors and are widespread in the skin, cornea, conjunctiva, and mucous membranes. Two subtypes of transient receptor potential channels interact with lacrimators. Transient receptor potential vanilloid 1 (TRPV1) is targeted by oleoresin capsicum, while transient receptor potential ankyrin 1 (TRPA1) is targeted by the other agents [3]. These receptors play an important role in the body’s ability to sense environmental, chemical, and physical stimuli, such as heat and pain, while also playing roles in inflammation [8]. By stimulating transient receptor potential channels, lacrimators exert their negative health effects, including tearing, blepharospasm, rhinorrhea, and mucous membrane irritation. These symptoms are typically short-lived and resolve after the exposed person is decontaminated and removed from the source of exposure [7].
Mechano-gated channels in C. elegans
Published in Journal of Neurogenetics, 2020
Transient receptor potential (TRP) channels are from a family of cation channels involved in a range of sensory processes counting chemosensation, thermosensation, mechanosensation and pain sensation (Arnadottir & Chalfie, 2010; Christensen & Corey, 2007) (Figure 2). TRP channels are classified into seven subfamilies (TRPA, TRPC, TRPML, TRPM, TRPN, TRPP and TRPV), which are tetrameric cation channels that can link to other molecular complexes required in various functions (Christensen & Corey, 2007; Montell, 2005). The importance of TRP ion channels is highlighted by a plethora of diseases and channelopathies in all major organs subjected to dysfunctions or mutations (Christensen & Corey, 2007; Nilius, Voets, & Peters, 2005). Interestingly, TRP channels are also present in single-celled organisms (protozoa) like yeast but limited to only TRPL, TRPM and TRPP channels (Venkatachalam, Luo, & Montell, 2014).
TRPV1 Antagonist Suppresses Allergic Conjunctivitis in a Murine Model
Published in Ocular Immunology and Inflammation, 2018
Ji Young Kwon, Hyun Soo Lee, Choun-Ki Joo
In mammals, the transient receptor potential (TRP) family of ion channels located on the plasma membrane act as receptors for stimuli. The TRP family consists of six subfamilies: TRPC (canonical: TRPC1~TRPC7); TRPV (vanilloid: TRPV1~TRPV6); TRPM (melastatin: TRPM1~TRPM8); TRPP (polycystin: TRPP2, TRPP3, TRPP5); TRPML (mucolipin: TRPML1~TRPML3); and TRPA (ankyrin: TRPA1).9 Among the TRP family, the immunologic functions of TRPA1 or TRPV1 have been researched in terms of their immunologic functions in the context of allergic disease. In allergic asthma, TRPA1 or TRPV1 yielded increased Th2 cytokine levels and induced the infiltration of eosinophils into the lungs.10,11 In an allergic dermatitis model, TRPA1 or TRPV1 induced the infiltration of inflammatory cells into the skin, increased Th2 cytokine levels, and provoked itching.12–14 In allergic rhinitis, TRPA1 or TRPV1 increased Th2 cytokine levels and promoted histamine-mediated itching. The increased levels of Th2 cytokines also led to the infiltration of inflammatory cells.15,16