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Nerve Endings: Branch-like terminations of Nerve fibers, sensory or motor Neurons. Endings of sensory neurons are the beginnings of afferent pathway to the Central nervous system. Endings of motor neurons are the terminals of axons at the muscle cells. Nerve endings which release neurotransmitters are called Presynaptic terminals.

Thermosensation

JoVE 10860

Peripheral thermosensation is the perception of external temperature. A change in temperature (on the surface of the skin and other tissues) is detected by a family of temperature-sensitive ion channels called Transient Receptor Potential, or TRP, receptors. These receptors are located on free nerve endings. Those detecting cold temperatures are closer to the surface of the skin than the nerve endings detecting warmth. These thermoTRP channels, while temperature selective, have relatively non-selective cation permeability. There are at least three types of receptors that are activated by cold, of which TRPM8 and TRPA1 are particularly sensitive. TRPM8 has a temperature sensitive range of about 10-26 oC (50-79 oF), and is largely associated with the perception of non-painful, or innocuous, cold. Menthol, a compound found in mint leaves, can also activate this receptor, which helps explain why this flavor is often perceived as cool. When temperatures are low enough to feel painful (i.e., noxious cold), TRPA1 receptors are activated. TRPA1 receptors respond to any temperature lower than 17 oC (~63 oF). There are at least seven receptors that respond to heat. Of these, five respond to temperatures in the innocuous warmth range: TRPM2 (23-38 oC, or ~73-100oF), TRPC5 (26-38 oC, or ~79-

 Core: Sensory Systems

Nociception

JoVE 10873

Nociception—the ability to feel pain—is essential for an organism’s survival and overall well-being. Noxious stimuli such as piercing pain from a sharp object, heat from an open flame, or contact with corrosive chemicals are first detected by sensory receptors, called nociceptors, located on nerve endings. Nociceptors express ion channels that convert noxious stimuli into electrical signals. When these signals reach the brain via sensory neurons, they are perceived as pain. Thus, pain helps the organism avoid noxious stimuli. The immune system plays an essential role in pain pathology. Upon encountering noxious stimuli, immune cells such as mast cells and macrophages present at the site of injury release inflammatory chemicals such as cytokines, chemokines, histamines, and prostaglandins. These chemicals attract other immune cells such as monocytes and T cells to the injury site. They also stimulate nociceptors, resulting in hyperalgesia—a more intense response to a previously painful stimulus, or allodynia—a painful response to a normally innocuous stimulus such as light touch. Such pain sensitization helps protect the injured site during healing. In some cases, pain outlives its role as an acute warning system if sensitization fails to resolve over time. Chronic pain—persistent or recurrent pain lasting longer than t

 Core: Musculoskeletal System

In Vitro Recording of Mesenteric Afferent Nerve Activity in Mouse Jejunal and Colonic Segments

1Laboratory of Experimental Medicine and Pediatrics, Division of Gastroenterology, University of Antwerp, 2Visceral Pain Group, Discipline of Medicine, University of Adelaide, 3Department of Biomedical Sciences, University of Sheffield, 4Department of Pharmacy, Pharmacology and Postgraduate Medicine, University of Hertfordshire, 5Department of Gastroenterology and Hepatology, Antwerp University Hospital

JoVE 54576

 Neuroscience

The Tongue and Taste Buds

JoVE 10850

The surface of the tongue is covered with various small bumps called papillae, which either distribute what has been ingested (filiform papillae) or contain the sensory taste (or gustatory) receptor cells (fungiform, circumvallate, and foliate papillae). Embedded within each taste-related papilla are the taste buds—clusters of 30 to 100 gustatory receptor cells.

Gustatory receptor cells extend finger-like projections called gustatory hairs (or microvilli) into a region known as the taste pore. Here, many of the cells contain receptors that detect different tastants—the molecules that can be tasted. The average number of taste buds varies significantly among individuals, with estimates ranging from 2,000-10,000 taste buds. Taste cells have a lifespan of about 10-14 days and are continually replaced. Thus, each taste bud contains taste cells at different stages of development. Aside from the filiform papillae, which do not contain taste buds, the mushroom-shaped fungiform papillae are the most numerous. Fungiform papillae are predominantly located on the anterior two-thirds of the tongue and contain between one and eight taste buds each. In contrast, the other two types of papillae—circumvallate and foliate—contain more than 100 taste buds per papilla. Circumvallate papillae, the largest type, are located at the back o

 Core: Sensory Systems

Local and Global Methods of Assessing Thermal Nociception in Drosophila Larvae

1Department of Biochemistry and Molecular Biology, The University of Texas MD Anderson Cancer Center, 2Scholars Academy/MARC Scholar, University of Houston-Downtown, 3Genes and Development Graduate Program, University of Texas Graduate School of Biomedical Sciences, 4Neuroscience Graduate Program, University of Texas Graduate School of Biomedical Sciences

JoVE 3837

 Neuroscience

Flat Mount Imaging of Mouse Skin and Its Application to the Analysis of Hair Follicle Patterning and Sensory Axon Morphology

1Department of Molecular Biology and Genetics, Howard Hughes Medical Institute, Johns Hopkins University School of Medicine, 2Department of Neuroscience, Howard Hughes Medical Institute, Johns Hopkins University School of Medicine, 3Department of Ophthalmology, Howard Hughes Medical Institute, Johns Hopkins University School of Medicine

JoVE 51749

 Neuroscience

Assessment of Dopaminergic Homeostasis in Mice by Use of High-performance Liquid Chromatography Analysis and Synaptosomal Dopamine Uptake

1Molecular Neuropharmacology and Genetics Laboratory, Lundbeck Foundation Center for Biomembranes in Nanomedicine, Department of Neuroscience and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, 2Laboratory of Neuropsychiatry, Psychiatric Center Copenhagen and Department of Neuroscience and Pharmacology, University of Copenhagen

JoVE 56093

 Neuroscience

Bovine Mammary Gland Biopsy Techniques

1National Animal Nutrition Program, a National Research Support Project (NRSP-9), Department of Animal and Food Sciences, University of Kentucky, 2School of Performing Arts, Virginia Tech, 3Department of Large Animal Clinical Sciences, The Virginia-Maryland College of Veterinary Medicine, Virginia Tech, 4Department of Dairy Science, Virginia Tech, 5Department of Animal Biosciences, University of Guelph, 6School of Visual Arts, Virginia Tech

JoVE 58602

 Biology

Targeting Alpha Synuclein Aggregates in Cutaneous Peripheral Nerve Fibers by Free-floating Immunofluorescence Assay

1Laboratory for Biomedical Neurosciences, Neurocenter of Southern Switzerland, 2Neurology Department, Neurocenter of Southern Switzerland, 3Department of Neurology, Inselspital, Bern University Hospital, University of Bern, 4Faculty of Biomedical Sciences, Università della Svizzera Italiana

JoVE 59558

 Neuroscience

Simultaneous Recordings of Cortical Local Field Potentials and Electrocorticograms in Response to Nociceptive Laser Stimuli from Freely Moving Rats

1CAS Key Laboratory of Mental Health, Institute of Psychology, 2Department of Psychology, University of Chinese Academy of Sciences, 3Research Center of Brain Cognitive Neuroscience, Liaoning Normal University, 4Neuroscience Research Institute, Peking University, 5Department of Neurobiology, School of Basic Medical Sciences, Peking University, 6Key Laboratory for Neuroscience, Ministry of Education/National Health and Family Planning Commission, Peking University, 7Department of Pain Management, State Key Clinical Specialty in Pain Medicine, Second Affiliated Hospital of Guangzhou Medical University

JoVE 58686

 Behavior

Loading a Calcium Dye into Frog Nerve Endings Through the Nerve Stump: Calcium Transient Registration in the Frog Neuromuscular Junction

1Laboratory of Biophysics of Synaptic Processes, Kazan Scientific Centre, Kazan Institute of Biochemistry and Biophysics, Russian Academy of Sciences, 2Open Laboratory of Neuropharmacology, Kazan Federal University, 3Department of Radiophotonics and Microwave Technologies, A.N. Tupolev Kazan National Research Technical University, 4Department of Medical and Biological Physics, Kazan State Medical University

JoVE 55122

 Neuroscience
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