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The Look and Feel of Food
Published in Alan R. Hirsch, Nutrition and Sensation, 2023
Sanford S. Sherman, Mary Beth Gallant-Shean, Alan R. Hirsch
Astringency is the perception of drying or puckering, as is prototypically seen in response to tannic acid in dry wine or the mouth somesthetic sensation in response to the introduction of strong lemon juice (Bates-Smith 1954). Such a sensation may reflect a combination of touch receptors, through meissner’s corpuscles and mechanoreception for deformation with activation of pacinian corpuscles. Such activation may come directly from the consumed thermal, or indirectly as a result of salivary production inhibition inducing changes to physiological set points in the oral epithelium, inducing greater sensitivity to chemical external stimuli (Joslyn and Goldstein 1964). Supporting such a theory, tannic acid-induced astringency (or dryness) was reduced by the addition of the sialogogue, sucrose (Lyman and Green 1990). The astringency of a food is partially dependent on its ability to precipitate salivary proteins (Noble 1995). Such precipitants reinforce astringency (Green 1993). Cross-linking of proteins may enhance tension thus stimulating mechanoreceptors.
Introduction
Published in J. Terrence Jose Jerome, Clinical Examination of the Hand, 2022
The positioning of the hand to grasp and adapt to its form is complex. More important is the regulation of the force of the grip. The force of grip must be varied depending upon the weight of the object, fragility (glass), surface characteristics (slippery, rough) and its utilization (Figure 1.40). Also, Pacinian corpuscles play a semi-automatic role in measuring and regulating the grasping force. Interestingly, there is always an overshoot of forces in the initial/first grasp of an unknown object, then the second/subsequent grasp automatically regulates the level of force required for prehension. In leprosy, the hand has lost its sensory safety signals, forcing the hand to non-healing wounds/ulcers by excessive pressure.
An introduction to skin and skin disease
Published in Rashmi Sarkar, Anupam Das, Sumit Sethi, Concise Dermatology, 2021
Recently, very fine nerve fibres have been identified in the epidermis, but most of the fibres run alongside the blood vessels in the dermal papillae and deeper in the dermis. There are several types of specialized sensory receptor in the upper dermis that detect particular sensations. Free nerve endings perceive touch, temperature, pain, and itch. Pacinian corpuscles respond to deep pressure and vibrations. Other sensory receptors include Golgi-Mazzoni corpuscles, Krause end bulbs, Meissner’s corpuscle (responding to dynamic pressure), Ruffini corpuscles (responding to stretching of the skin), and mucocutaneous end organs.
Acute physiological and functional effects of repetitive shocks on the hand–arm system: a pilot study on healthy subjects
Published in International Journal of Occupational Safety and Ergonomics, 2023
Jonathan Witte, Alexandra Corominas, Benjamin Ernst, Uwe Kaulbars, Robert Wendlandt, Hans Lindell, Elke Ochsmann
The pathophysiological causes of the effects found cannot be determined by this pilot study. However, a conceivable explanation is the inhibition of cutaneous mechanoreceptors [42], disrupted myelinated axons and denervation of mechanosensory end organs observed in animal experiments [10,43]. A transient VPT shift, especially with higher test stimuli, implies the impairment of Meissner’s corpuscles and equally rapidly adapting Pacinian corpuscles with a maximal vibrational sensitivity at approximately 300 Hz [44]. This is of clinical relevance, as longitudinal results on vibration exposed workers suggest that an altered temporary threshold shift can influence the permanent VPT and thus structural integrity of mechanoreceptors and Aβ afferent nerve fibres over time [45]. Resulting symptoms of a peripheral neuropathy, such as numbness, tingling and reduced manual dexterity, can therefore be effectively reduced by occupational health interventions and prevention offers.
Evaluation of the biodynamic response of the hand–arm system and hand-tool designs: a brief review
Published in International Journal of Occupational Safety and Ergonomics, 2023
Jain A. R. Tony B, M.S. Alphin
A pallesthesiometer device is used to detect the sense of vibration at the tip of the finger. An accelerometer is put on a counterbalanced vibration exciter as part of the set-up [36]. The contact probe is placed on the fingertip in such a way that the contact force and finger force remain constant [37]. The vibration intensity is increased until the subject presses a response button and demonstrates recognition. The magnitude lowers automatically, and the cycle repeats until a Bekesy-type trace is obtained [38]. The Meissner and Pacinian corpuscles are represented by frequencies of 31.5 and 125 Hz, respectively. After that, the mean thresholds for these two frequencies are determined [39]. Vibrotactile thresholds can be pretentious by age, temporary threshold shift, overall vibration exposure, vibration frequency, contactor configuration, fingertip temperature and area [40]. Standard No. ISO 13091-1:2001 established for measuring normative thresholds [36] and vibrotactile thresholds based on a few research studies were proposed by Standard No. ISO 13091-2:2003 [37].
Vibrotactile perception in Dupuytren disease
Published in Journal of Plastic Surgery and Hand Surgery, 2021
Tiffany L. Held, Mahdi Ahmadi, Rajesh Rajamani, Victor H. Barocas, Amy T. Moeller
Patients with DD have been found to exhibit structural changes in the Pacinian corpuscles (PCs) of the affected tissue [10–14]. As cutaneous mechanoreceptors in the deep dermis and subcutaneous tissue, PCs are sensitive to pressure changes and vibration in the frequency range of 20–1000 Hz [15]. Structurally, PCs consist of concentric lamellae surrounding an RA II nerve ending [16]; this structure acts as a high–pass filter and enables high sensitivity to vibrational stimuli via interconnected collagen fibers [15,16]. Ehremantant et al. reported that PCs from subjects with DD exhibited larger size and more numerous lamellae. The mean area of PCs from non-DD subjects was 1.0 ± 0.5 mm2, whereas the mean area of the PCs from subjects with DD was 2.6 ± 0.4 mm2 (p ≤ 0.001); the number of layers increased from 40 ± 9 in subjects without DD to 64 ± 14 (p ≤ 0.01) [12]. Given the PC’s role in vibrotactile sensing, one may ask whether the structural changes associate with perception changes.