Show Advanced Search

REFINE YOUR SEARCH:

Containing Text
- - -
+
Filter by author or institution
GO
Filter by publication date
From:
October, 2006
Until:
Today
Filter by journal section

Filter by science education

 
 
Calcium Channels: Voltage-dependent cell membrane glycoproteins selectively permeable to calcium ions. They are categorized as L-, T-, N-, P-, Q-, and R-types based on the activation and inactivation kinetics, ion specificity, and sensitivity to drugs and toxins. The L- and T-types are present throughout the cardiovascular and central nervous systems and the N-, P-, Q-, & R-types are located in neuronal tissue.

Ion Channels

JoVE 10722

Ion channels maintain the membrane potential of a cell. For most cells, especially excitable ones, the inside has a more negative charge than the outside of the cell, due to a greater number of negative ions than positive ions. For excitable cells, like firing neurons, contracting muscle cells, or sensory touch cells, the membrane potential must be able to change rapidly moving from a negative membrane potential to one that is more positive. To achieve this, cells rely on two types of ion channels: ligand-gated and voltage-gated. Ligand-gated ion channels, also called ionotropic receptors, are transmembrane proteins that form a channel but which also have a binding site. When a ligand binds to the surface, it opens the ion channel. Common ionotropic receptors include the NMDA, kainite, and AMPA glutamate receptors and the nicotinic acetylcholine receptors. When a ligand, like glutamate or acetylcholine, binds to its receptor it allows the influx of sodium (Na+) and calcium (Ca++) ions into the cells. The positive ions, or cations, follow down their electrochemical gradient, moving from the more positive extracellular surface to the less positive (more negative) intracellular surface. This changes the membrane potential near the receptor, which can then activate nearby voltage gated ion channels to propagate the change in membrane potential throughout the cell

 Core: Cell Signaling

Muscle Contraction

JoVE 10869

In skeletal muscles, acetylcholine is released by nerve terminals at the motor end plate-the point of synaptic communication between motor neurons and muscle fibers. Binding of acetylcholine to its receptors on the sarcolemma allows entry of sodium ions into the cell and triggers an action potential in the muscle cell. Thus, electrical signals from the brain are transmitted to the muscle. Subsequently, the enzyme acetylcholinesterase breaks down acetylcholine to prevent excessive muscle stimulation. Individuals with the disorder myasthenia gravis, develop antibodies against the acetylcholine receptor. This prevents transmission of electrical signals between the motor neuron and muscle fiber and impairs skeletal muscle contraction. Myasthenia gravis is treated using drugs that inhibit acetylcholinesterase (allowing more opportunities for the neurotransmitter to stimulate the remaining receptors) or suppress the immune system (preventing the formation of antibodies). Unlike skeletal muscles, smooth muscles present in the walls of internal organs are innervated by the autonomic nervous system and undergo involuntary contractions. Contraction is mediated by the interaction between two filament proteins-actin and myosin. The interaction of actin and myosin is closely linked to intracellular calcium concentration. In response to neurotransmitter or hormone sig

 Core: Musculoskeletal System

Hair Cells

JoVE 10854

Hair cells are the sensory receptors of the auditory system—they transduce mechanical sound waves into electrical energy that the nervous system can understand. Hair cells are located in the organ of Corti within the cochlea of the inner ear, between the basilar and tectorial membranes. The actual sensory receptors are called inner hair cells. The outer hair cells serve other functions, such as sound amplification in the cochlea, and are not discussed in detail here. Hair cells are named after the hair-like stereocilia that protrude from their tops and touch the tectorial membrane. The stereocilia are arranged by height and are attached by thin filaments called tip links. The tip links are connected to stretch-activated cation channels on the tips of the stereocilia. When a sound wave vibrates the basilar membrane, it creates a shearing force between the basilar and tectorial membranes that moves the hair cell stereocilia from side to side. When the cilia are displaced towards the tallest cilium, the tip links stretch, opening the cation channels. Potassium (K+) then flows into the cell, because there is a very high concentration of K+ in the fluid outside of the stereocilia. This large voltage difference creates an electrochemical gradient that causes an influx of K+ once the channels are opened. This influx o

 Core: Sensory Systems

The Synapse

JoVE 10997

Neurons communicate with one another by passing on their electrical signals to other neurons. A synapse is the location where two neurons meet to exchange signals. At the synapse, the neuron that sends the signal is called the presynaptic cell, while the neuron that receives the message is called the postsynaptic cell. Note that most neurons can be both presynaptic and postsynaptic, as they both transmit and receive information. An electrical synapse is one type of synapse in which the pre- and postsynaptic cells are physically coupled by proteins called gap junctions. This allows electrical signals to be directly transmitted to the postsynaptic cell. One feature of these synapses is that they can transmit electrical signals extremely quickly—sometimes at a fraction of a millisecond—and do not require any energy input. This is often useful in circuits that are part of escape behaviors, such as that found in the crayfish that couples the sensation of a predator with the activation of the motor response. In contrast, transmission at chemical synapses is a stepwise process. When an action potential reaches the end of the axonal terminal, voltage-gated calcium channels open and allows calcium ions to enter. These ions trigger fusion of neurotransmitter-containing vesicles with the cellular membrane, releasing neurotransmitters into the small space b

 Core: Nervous System

Real-time Live-cell Flow Cytometry to Investigate Calcium Influx, Pore Formation, and Phagocytosis by P2X7 Receptors in Adult Neural Progenitor Cells

1Griffith Institute for Drug Discovery, Griffith University, 2Australian Institute for Bioengineering and Nanotechnology, University of Queensland, 3Discipline of Anatomy and Histology, School of Medical Science, University of Sydney, 4Bosch Institute, University of Sydney, 5Applied Neurosciences Program, Peter Duncan Neurosciences Research Unit, St. Vincent's Centre for Applied Medical Research, 6School of Medical Sciences, The University of New South Wales (UNSW) Medicine, Sydney, New South Wales, 7School of Environment and Science, Griffith University, Brisbane, Queensland, 8Florey Institute of Neuroscience and Mental Health, University of Melbourne

JoVE 59313

 Developmental Biology

Contractility Measurements of Human Uterine Smooth Muscle to Aid Drug Development

1Harris-Wellbeing Preterm Birth Research Centre, Department of Cellular and Molecular Physiology, Institute of Translational Medicine, University of Liverpool, 2School of Biomedical Sciences, The University of Queensland, 3Faculty of Chemistry, Institute of Biological Chemistry, University of Vienna, 4Institute for Molecular Bioscience, University of Queensland, 5Center for Physiology and Pharmacology, Medical University of Vienna

JoVE 56639

 Medicine

Measurement of Ion Concentration in the Unstirred Boundary Layer with Open Patch-Clamp Pipette: Implications in Control of Ion Channels by Fluid Flow

1Department of Physiology, KU Open Innovation Center, Research Institute of Medical Science, Konkuk University School of Medicine, 2Department of Emergency Medical Services, Eulji University, 3Department of Mechanical Engineering, Sungkyunkwan University

JoVE 58228

 Biochemistry

Crystal Structure of the N-terminal Domain of Ryanodine Receptor from Plutella xylostella

1Tianjin Key Laboratory for Modern Drug Delivery & High-Efficiency, Collaborative Innovation Center of Chemical Science and Engineering, School of Pharmaceutical Science and Technology, Tianjin University, 2State Key Laboratory of Ecological Pest Control for Fujian/Taiwan Crops and Institute of Applied Ecology, Fujian Agriculture and Forestry University, 3Joint International Research Laboratory of Ecological Pest Control, Ministry of Education, Fuzhou, 4Fujian-Taiwan Joint Centre for Ecological Control of Crop Pests, Fujian Agriculture and Forestry University

JoVE 58568

 Biochemistry

Imaging Neural Activity in the Primary Somatosensory Cortex Using Thy1-GCaMP6s Transgenic Mice

1Spinal Cord and Brain Injury Research Group, Stark Neurosciences Research Institute, Department of Neurological Surgery and Goodman and Campbell Brain and Spine, Department of Anatomy and Cell Biology, Indiana University School of Medicine, 2Department of Spinal Cord Injury and Repair, Trauma and Orthopedics Institute of Chinese PLA, General Hospital of Jinan Military Region, 3Department of Orthopedics, Shandong Cancer Hospital, Shandong University, 4Department of Neurobiology, Institute of Basic Medical Sciences, Academy Military Medical Sciences

JoVE 56297

 Neuroscience

In Vivo Single-Molecule Tracking at the Drosophila Presynaptic Motor Nerve Terminal

1Clem Jones Centre for Ageing Dementia Research, Queensland Brain Institute, The University of Queensland, 2VIB Centre for Brain and Disease Research, KU Leuven Department of Neurosciences, Leuven Institute for Neurodegenerative Disease (LIND), 3Queensland Brain Institute, The University of Queensland

JoVE 56952

 Neuroscience

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

Measuring Physiological Responses of Drosophila Sensory Neurons to Lipid Pheromones Using Live Calcium Imaging

1Temasek Life Sciences Laboratory, 2Department of Biological Science, National University of Singapore, 3Bioimaging and Biocomputing Facility, Temasek Life Sciences Laboratory, 4Histology and Light Microscopy Core, Gladstone Institutes, 5Pacific Biosciences Research Center, University of Hawai'i at Mānoa

JoVE 53392

 Immunology and Infection
12
More Results...