Search results “Electric signals meaning”
Transmission Lines - Signal Transmission and Reflection
Visualization of the voltages and currents for electrical signals along a transmission line. My Patreon page is at https://www.patreon.com/EugeneK
This Is How Your Brain Powers Your Thoughts
Scientists have figured out how our brains process thoughts and the explanation will blow your mind. Can Shocking Your Brain Make You Smarter? - https://youtu.be/LSwMwX9BbGc Sign Up For The Seeker Newsletter Here - http://bit.ly/1UO1PxI We got nominated for a People's Choice Webby! That means, you can help us win. Please, take a minute and vote for us here (thanks!): https://vote.webbyawards.com/PublicVoting#/2017/film-video/general-film/vr-cinematic-or-pre-rendered Read More: Does Thinking Really Hard Burn More Calories? https://www.scientificamerican.com/article/thinking-hard-calories/ "Unlike physical exercise, mental workouts probably do not demand significantly more energy than usual. Believing we have drained our brains, however, may be enough to induce weariness." Human Brain Loses Billions of Neurons in New Analysis http://www.livescience.com/18749-human-brain-cell-number.html "The whole human race just got a little dumber: A new analysis of the number of neurons, those brain cells that transmit thoughts, in the human brain has come back with a staggeringly lower number than thought -- 14 billion brain cells fewer, about the size of the baboon brain." Brain cells mobilize sugar in response to increased activity https://medicalxpress.com/news/2017-01-brain-cells-mobilize-sugar-response.html "New research is providing insights into why the brain is so reliant on sugar to function. In a study published Jan. 19 in Neuron, a research team led by Weill Cornell Medicine investigators discovered that brain cells recruit a specific sugar, glucose, to fuel the transmission of electrical signals that enable people to think, breathe and walk." ____________________ Seeker inspires us to see the world through the lens of science and evokes a sense of curiosity, optimism and adventure. Watch More Seeker on our website http://www.seeker.com/shows/ Subscribe now! http://www.youtube.com/subscription_center?add_user=dnewschannel Seeker on Twitter http://twitter.com/seeker Trace Dominguez on Twitter https://twitter.com/tracedominguez Seeker on Facebook https://www.facebook.com/SeekerMedia/ Seeker on Google+ https://plus.google.com/u/0/+dnews Seeker http://www.seeker.com/ Sign Up For The Seeker Newsletter Here: http://bit.ly/1UO1PxI Written by: Julian Huguet
Views: 278495 Seeker
Difference between AC and DC Current Explained | AddOhms #5
What is the difference between AC and DC? Support on Patreon: https://patreon.com/baldengineer AC and DC current explained by James the Bald Engineer. Using simple circuits for each type of electricity, you will learn why they are different. Show notes: http://addohms.com/ep5 Previous video mention: http://www.youtube.com/watch?v=lYZUXV-v71Y
Views: 736237 AddOhms
Cardiac Conduction System and Understanding ECG, Animation.
This video and other related images/videos (in HD) are available for instant download licensing here: https://www.alilamedicalmedia.com/-/galleries/images-videos-by-medical-specialties/cardiology-and-vascular-diseases ©Alila Medical Media. All rights reserved. Support us on Patreon and get FREE downloads and other great rewards: patreon.com/AlilaMedicalMedia The cardiac conduction system consists of the following components: - The sinoatrial node, or SA node, located in the right atrium near the entrance of the superior vena cava. This is the natural pacemaker of the heart. It initiates all heartbeat and determines heart rate. Electrical impulses from the SA node spread throughout both atria and stimulate them to contract. - The atrioventricular node, or AV node, located on the other side of the right atrium, near the AV valve. The AV node serves as electrical gateway to the ventricles. It delays the passage of electrical impulses to the ventricles. This delay is to ensure that the atria have ejected all the blood into the ventricles before the ventricles contract. - The AV node receives signals from the SA node and passes them onto the atrioventricular bundle - AV bundle or bundle of His. - This bundle is then divided into right and left bundle branches which conduct the impulses toward the apex of the heart. The signals are then passed onto Purkinje (pur-KIN-jee) fibers, turning upward and spreading throughout the ventricular myocardium. Electrical activities of the heart can be recorded in the form of electrocardiogram, ECG or EKG. An ECG is a composite recording of all the action potentials produced by the nodes and the cells of the myocardium. Each wave or segment of the ECG corresponds to a certain event of the cardiac electrical cycle. When the atria are full of blood, the SA node fires, electrical signals spread throughout the atria and cause them to depolarize. This is represented by the P wave on the ECG. Atrial contraction , or atrial systole (SIS-toe-lee) starts about 100 mili-seconds after the P wave begins. The P-Q segment represents the time the signals travel from the SA node to the AV node. The QRS complex marks the firing of the AV node and represents ventricular depolarization: - Q wave corresponds to depolarization of the interventricular septum. - R wave is produced by depolarization of the main mass of the ventricles. - S wave represents the last phase of ventricular depolarization at the base of the heart. - Atrial repolarization also occurs during this time but the signal is obscured by the large QRS complex. The S-T segment reflects the plateau in the myocardial action potential. This is when the ventricles contract and pump blood. The T wave represents ventricular repolarization immediately before ventricular relaxation, or ventricular diastole (dy-ASS-toe-lee). The cycle repeats itself with every heartbeat. All images/videos by Alila Medical Media are for information purposes ONLY and are NOT intended to replace professional medical advice, diagnosis or treatment. Always seek the advice of a qualified healthcare provider with any questions you may have regarding a medical condition.
Views: 2263490 Alila Medical Media
What is RMS value | Easiest Explanation | TheElectricalGuy
The video will help you to learn the basics about RMS value. The RMS value is an important term in electrical engineering. But, what is the exact meaning of RMS value? And why it is so much important? Well, if you have the same questions, you have clicked the right Video. To get the easiest explanation of what is RMS value, watch the video. Why AC suppy is always represented by a sine wave? - https://youtu.be/voEL6rOWaLU For more interesting videos & articles about electrical engineering visit – www.theelectricalguy.in Find me: Facebook – https://www.facebook.com/IamTheElectricalGuy/ Instagram – https://www.instagram.com/the_electricalguy/ Twitter - https://twitter.com/DElectricalGuy YouTube - http://www.youtube.com/c/GauravJ  Google + - https://plus.google.com/u/0/+GauravRJ00
Introduction to Bioelectricity | PurdueX on edX | Course About Video
Understand how biological systems generate electrical signals, and how they can be recorded and induced with manufactured devices. Sign up for this course here: https://www.edx.org/course/introduction-bioelectricity-purduex-nano525x In this course you will use fundamental engineering and mathematical tools to understand and analyze basic bioelectricity and circuit theory in the context of the mammalian nervous system. This course is for students who are interested in learning about relating the systems of the human body that involve or communicate with bioelectrical systems, including the heart, brain, muscles, and the neuromuscular system that connects them all together. Students will learn how bioelectricity can be used to record and control the way the body electric behaves. Suggested text: “Neuroscience” by Purves, et al. This course is offered by the nanoHUB-U project, which is jointly funded by Purdue and NSF with the goal of transcending disciplines through short courses accessible to students in any branch of science or engineering. These courses focus on cutting-edge topics distilled into short lectures with quizzes, homework, and practice exams. What you'll learn Fundamentals of bioelectricity of the mammalian nervous system and other excitable tissues Passive and active forms of electric signals in both the single cell and cell-cell communication Tissue and systemic bioelectricity Mathematical analysis including Nernst equation, Goldman equation, linear cable theory, and Hodgkin-Huxley Model of action potential generation and propagation To design and build a wireless bioelectric recording device to control a prosthetic limb
Views: 6068 edX
Warning lights on your car's dashboard - what do they mean?
Ever wondered what those colorful lights in the speedometer console meant? While, here you go! PS: Do refer to the owners manual of your car for exact description.
Views: 1588979 CARS24
The Nervous System, Part 2 - Action! Potential!: Crash Course A&P #9
•••SUBBABLE MESSAGE••• TO: Carla FROM: Christopher Next stop is whenever. Just be like, "stop." *** You can directly support Crash Course at http://www.subbable.com/crashcourse Subscribe for as little as $0 to keep up with everything we're doing. Also, if you can afford to pay a little every month, it really helps us to continue producing great content. *** What do you and a sack of batteries have in common? Today, Hank explains. -- Table of Contents: Ion Channels Regulate Electrochemistry to Create Action Potential 4:51 Resting State 3:22 Depolarization 6:09 Repolarization 7:35 Hyperpolarization 8:00 -- CRASH COURSE KIDS! http://www.youtube.com/crashcoursekids Want to find Crash Course elsewhere on the internet? Facebook - http://www.facebook.com/YouTubeCrashCourse Twitter - http://www.twitter.com/TheCrashCourse Tumblr - http://thecrashcourse.tumblr.com Support CrashCourse on Subbable: http://subbable.com/crashcourse
Views: 3225392 CrashCourse
Electromagnetic Spectrum: Radio Waves
http://www.facebook.com/ScienceReason ... [email protected]: EMS Electromagnetic Spectrum (Episode 2) - Radio Waves The electromagnetic spectrum is the range of all possible frequencies of electromagnetic radiation. The "electromagnetic spectrum" of an object is the characteristic distribution of electromagnetic radiation emitted or absorbed by that particular object. --- Please SUBSCRIBE to Science & Reason: • http://www.youtube.com/Best0fScience • http://www.youtube.com/ScienceTV • http://www.youtube.com/FFreeThinker --- MEASURING THE ELECTROMAGNETIC SPECTRUM The electromagnetic (EM) spectrum is just a name that scientists give a bunch of types of radiation when they want to talk about them as a group. Radiation is energy that travels and spreads out as it goes - visible light that comes from a lamp in your house and radio waves that come from a radio station are two types of electromagnetic radiation. Other examples of EM radiation are microwaves, infrared and ultraviolet light, X-rays and gamma-rays. Hotter, more energetic objects and events create higher energy radiation than cool objects. Only extremely hot objects or particles moving at very high velocities can create high-energy radiation like X-rays and gamma-rays. • http://imagine.gsfc.nasa.gov/docs/science/know_l1/emspectrum.html --- RADIO WAVES Radio waves are a type of electromagnetic radiation with wavelengths in the electromagnetic spectrum longer than infrared light. Like all other electromagnetic waves, they travel at the speed of light. Naturally-occurring radio waves are made by lightning, or by astronomical objects. Artificially-generated radio waves are used for fixed and mobile radio communication, broadcasting, radar and other navigation systems, satellite communication, computer networks and innumerable other applications. Different frequencies of radio waves have different propagation characteristics in the Earth's atmosphere; long waves may cover a part of the Earth very consistently, shorter waves can reflect off the ionosphere and travel around the world, and much shorter wavelengths bend or reflect very little and travel on a line of sight. Discovery and utilization: Radio waves were first predicted by mathematical work done in 1865 by James Clerk Maxwell. Maxwell noticed wavelike properties of light and similarities in electrical and magnetic observations. He then proposed equations, that described light waves and radio waves as waves of electromagnetism that travel in space. In 1887, Heinrich Hertz demonstrated the reality of Maxwell's electromagnetic waves by experimentally generating radio waves in his laboratory. Many inventions followed, making practical the use of radio waves to transfer information through space. Propagation: The study of electromagnetic phenomena such as reflection, refraction, polarization, diffraction and absorption is of critical importance in the study of how radio waves move in free space and over the surface of the Earth. Different frequencies experience different combinations of these phenomena in the Earth's atmosphere, making certain radio bands more useful for specific purposes than others. Radio communication: In order to receive radio signals, for instance from AM/FM radio stations, a radio antenna must be used. However, since the antenna will pick up thousands of radio signals at a time, a radio tuner is necessary to tune in to a particular frequency (or frequency range). This is typically done via a resonator (in its simplest form, a circuit with a capacitor and an inductor). The resonator is configured to resonate at a particular frequency (or frequency band), thus amplifying sine waves at that radio frequency, while ignoring other sine waves. Usually, either the inductor or the capacitor of the resonator is adjustable, allowing the user to change the frequency at which it resonates. In medicine: Radio frequency (RF) energy has been used in medical treatments for over 75 years generally for minimally invasive surgeries and coagulation, including the treatment of sleep apnea. • http://en.wikipedia.org/wiki/Radio_waves .
Views: 388868 Best0fScience
Views: 5168 Walter Jahn
Electrical system of the heart | Circulatory system physiology | NCLEX-RN | Khan Academy
See where the pacemaker cells start the electrical wave of depolarization, and how it gets all the way to the ventricles of the heart. Rishi is a pediatric infectious disease physician and works at Khan Academy. Created by Rishi Desai. Watch the next lesson: https://www.khanacademy.org/test-prep/nclex-rn/nclex-rn-circulatory-system/heart-depolarization-ddp/v/a-race-to-keep-pace?utm_source=YT&utm_medium=Desc&utm_campaign=Nclex-rn Missed the previous lesson? https://www.khanacademy.org/test-prep/nclex-rn/nclex-rn-circulatory-system/heart-depolarization-ddp/v/depolarization-waves-flowing-through-the-heart?utm_source=YT&utm_medium=Desc&utm_campaign=Nclex-rn NCLEX-RN on Khan Academy: A collection of questions from content covered on the NCLEX-RN. These questions are available under a Creative Commons Attribution-NonCommercial-ShareAlike 3.0 United States License (available at http://creativecommons.org/licenses/by-nc-sa/3.0/us/). About Khan Academy: Khan Academy offers practice exercises, instructional videos, and a personalized learning dashboard that empower learners to study at their own pace in and outside of the classroom. We tackle math, science, computer programming, history, art history, economics, and more. Our math missions guide learners from kindergarten to calculus using state-of-the-art, adaptive technology that identifies strengths and learning gaps. We've also partnered with institutions like NASA, The Museum of Modern Art, The California Academy of Sciences, and MIT to offer specialized content. For free. For everyone. Forever. #YouCanLearnAnything Subscribe to Khan Academy’s NCLEX-RN channel: https://www.youtube.com/channel/UCDx5cTeADCvKWgF9x_Qjz3g?sub_confirmation=1 Subscribe to Khan Academy: https://www.youtube.com/subscription_center?add_user=khanacademy
Views: 957497 khanacademymedicine
Bio electric potential definition
- Medical electronics, origin of bio potentials , -bio potential definition .
Views: 1429 vagupparai
Intro to AC Circuits using Phasors and RMS Voltage and Current | Doc Physics
We will use a cool method of describing the oscillation of current and voltage called phasors, which are fixed-length vectors that rotate at a constant frequency. It will be very fun. Yes, really.
Views: 468694 Doc Schuster
Demonstrating All 7 Modes in Parallel [MODAL MUSIC THEORY]
Support these lessons on Patreon! https://bit.ly/2zFwzOO 01:08-Theory 04:20- Begin the Tour with Major 05:33-Dorian 06:49-Phrygian 07:57-Lydian 08:56-Mixolydian 10:26-Minor/Aeolian 11:44-Locrian 13:16-Related Theory Building the modes in parallel (starting from the same root) allows you to see and hear the differences. Learn each mode's unique identity , so you can easily identify it when you hear it, and be able to employ its characteristics when composing. Learning the modes of the major scale is very important, but the topic is often difficult to fully grasp. There are many ways to look at modes, and this video explores each mode in parallel, meaning each mode is played from an unchanging root (in this case, G). Normally modes are taught as being related- C major is the same thing as D dorian is the same thing as E Phrygian, etc. But looking at the modes in parallel like demonstrated here allows a different perspective of why the concept of modes is important. https://www.twitter.com/signals_music https://www.facebook.com/signalsmusicstudio https://www.signalsmusicstudio.com Free online guitar lessons for beginners, intermediate, and advanced players. Located in Crystal Lake, Jake Lizzio provides free jam tracks and video lessons for guitar players, as well as music theory videos and other music education content.
Views: 368408 Signals Music Studio
Duty cycle, frequency and pulse width--an explanation
These terms are often confused or used interchangeably, when they are actually three different ways of measuring an electrical signal.
Views: 171077 Justin Miller
Heart Blocks, Anatomy and ECG Reading, Animation.
This video and other related images/videos (in HD) are available for instant download licensing here: https://www.alilamedicalmedia.com/-/galleries/images-videos-by-medical-specialties/cardiology-and-vascular-diseases ©Alila Medical Media. All rights reserved. Voice by: Sue Stern. Support us on Patreon and get FREE downloads and other great rewards: patreon.com/AlilaMedicalMedia All images/videos by Alila Medical Media are for information purposes ONLY and are NOT intended to replace professional medical advice, diagnosis or treatment. Always seek the advice of a qualified healthcare provider with any questions you may have regarding a medical condition. Heart block is a group of diseases characterized by presence of an obstruction, or a “BLOCK” in the heart electrical pathway. A block may slow down the conduction of electrical impulses, OR, in more severe cases, completely stop them. Heart blocks are classified by location where the blockage occurs. Accordingly, there are: SA nodal blocks, AV nodal blocks, intra-Hisian blocks, bundle branch blocks and fascicular blocks. Of these, AV nodal blocks, or AV blocks, are most clinically significant. In fact, very commonly, the term “heart block “, if not specified otherwise, is used to describe AV blocks. In AV blocks, the electrical signals are slow to reach the ventricles, or completely interrupted before reaching the ventricles. There are three degrees of AV block: First-degree AV block: the electrical signals are SLOWED as they pass from the SA node to the AV node, but all of them eventually reach the ventricle. On an ECG, this is characterized by a longer PR interval of more than 5 small squares. First-degree AV blocks rarely cause symptoms or problems and generally do NOT require treatment. Second-degree AV blocks are divided further into type I and type II: - In type I, the electrical signals are delayed further and further with each heartbeat until a beat is missing completely. On an ECG, this is seen as PROGRESSIVE prolongation of PR interval followed by a P wave WITHOUT a QRS complex. This is known as a “blocked” P wave or a “dropped” QRS complex. The cycle then re-starts over. As this usually repeats in regular cycles, there is a fixed ratio between the number of P waves and the number of QRS complexes per cycle. The number of QRS complexes always equals the number of P waves MINUS one. In this example, there are four P waves for every three QRS complexes. This is a “4 to 3” heart block. Second-degree type I blocks are usually mild and no specific treatment is indicated. - In type II second degree blocks, some of the electrical signals do NOT reach the ventricles. On an ECG, this is seen as intermittent non-conducted P-waves. The PR interval, however, remains CONSTANT in conducted beats. In majority of cases, the successfully conducted QRS complexes may appear broader than usual. In some type II blocks, there is a fixed number of P waves per QRS complex. In this example, there are three P waves for every QRS complex and the condition is described as “3 to 1” heart block. However, as the nature of type II block is unstable, this ratio is likely to change over time. Second- degree type II is less common than second-degree type I but is much more dangerous as it frequently progresses to complete heart block or cardiac arrest. Implantation of an artificial pacemaker is recommended for treatment of this type of AV blocks. Third-degree AV blocks are also referred to as complete heart blocks. In this condition, NONE of the electrical signals from the atria reach the ventricles. With NO input coming from the atria, the ventricles usually try to generate some impulses on their own. This is known as an “ESCAPE rhythm”. On an ECG, two independent rhythms can be seen: a regular P wave pattern represents atrial rhythm; and a regular, but UNUSUALLY slow QRS pattern represents the escape rhythm. The PR interval is variable as there is NO relationship between the 2 rhythms. Patients with third-degree heart blocks are at high risk of cardiac arrest. They require immediate treatment, cardiac monitoring and pacemaker implantation.
Views: 158008 Alila Medical Media
CAN Bus Explained - A Simple Intro (2018)
What is CAN bus? In this intro we explain the basics of CAN, incl. advantages, history, messages and the relation to protocols like J1939, OBD2 and CANopen! For the article, go to: http://www.csselectronics.com/screen/page/simple-intro-to-can-bus For a quick intro to our CAN bus analyzers, check out the below! https://youtu.be/649-piaJM1s In short, the Controller Area Network (CAN) is a standard used to allow Electronic Control Units (ECUs) to communicate in an efficient manner without a central computer. Messages are broadcast in a system that requires very little physical wiring making CAN bus low cost, robust and efficient. Applications of the CAN protocol include in particular automotive (cars, trucks, buses, commercial vehicles etc.), but also e.g. boats, drones and industrial automation. This video stays light - so some technical aspects are not covered. However, for more articles like this, check out our INTEL page: http://www.csselectronics.com/screen/page/can-bus-articles-tools-cases In particular, you may want to check out our other simple intros: OBD2 Explained: http://www.csselectronics.com/screen/page/simple-intro-obd2-explained SAE J1939 Explained: http://www.csselectronics.com/screen/page/simple-intro-j1939-explained We keep adding more articles and videos, so subscribe to get updates! ___________________________________________ At CSS Electronics, we offer powerful, simple and affordable CAN analyzers. Our CLX000 series doubles as both a powerful CAN logger with 8GB SD card and a CAN interface integrating with Wireshark. Features include advanced configuration options, DBC file data conversion support (incl. for J1939), real-time graphical plots, OBD2 Wireshark dissector - and much more. Pricing starts at 169 EUR with free international shipping and 100% free software. For more details, check out http://www.csselectronics.com ! SUBSCRIBE to our channel for more great videos - or get updates via our quarterly newsletter: http://eepurl.com/cR_ZhT
Views: 317101 CSS Electronics
How do fish make electricity? - Eleanor Nelsen
Check out our Patreon page: https://www.patreon.com/teded View full lesson: https://ed.ted.com/lessons/how-do-fish-make-electricity-eleanor-nelsen Nearly 350 species of fish have specialized anatomical structures that generate and detect electrical signals. Underwater, where light is scarce, electrical signals offer ways to communicate, navigate, find, and sometimes stun prey. But how do these fish produce electricity? And why? Eleanor Nelsen illuminates the science behind electric fish. Lesson by Eleanor Nelsen, directed by TOTEM Studio. Thank you so much to our patrons for your support! Without you this video would not be possible! Amber Wood, Ophelia Gibson Best, Cas Jamieson, Phyllis Dubrow, Michelle Stevens-Stanford, Aliyya Rachmadi, Eunsun Kim, Samantha Chow, Philippe Spoden, Mark Sasse II, Ayala Ron, Armando Ello, Manognya Chakrapani, Doreen Reynolds-Consolati, Simon Holst Ravn, Rakshit Kothari, Melissa Sorrells, Antony Lee, Husain Mohammad, Dino Hrnjić, Côme Vincent, Daniel Mardale, Alessandra Tasso, Zhufeng Wang, Astia Rizki Safitri.
Views: 1218426 TED-Ed
Electrical waveform | Waveforms | Aravali College | Smoothing | Pulsating | Current | K. V. | Ghamas
A waveform can be defined as the shape and form of a signal such as a wave moving in a physical medium or an abstract representation. To understand the different types of (A.C. & D.C.) waveform. Waveform diagrams, how to read them.
Views: 6695 Ghamas
Hackaday Logic Series: TTL Electrical characteristics.
From Gates to FPGAs Part 2: TTL Electrical characteristics. Explore the properties of various TTL components on our journey through gate logic toward complex programmable concepts. What are the values that make up a 1 and a 0? How do chips of different voltage levels work with one another? This and more in this installment! Read the entire article: http://wp.me/pk3lN-FJH
Views: 10201 HACKADAY
What is Actuator Types of actuator | Electrical & Automation Guru
An actuator is a device that produces a motion by converting energy and signals going into the system. The motion it produces can be either rotary or linear. Linear actuators produce linear motion. Meaning they can move forward or backwards on a set linear plane. Rotary actuators on the other hand produce rotary motion, meaning that the actuator revolves on a circular plane. Unlike linear actuators, rotary actuators are not limited by a set path; it can keep rotating in the same direction for as long as necessary. An actuator requires a control signal and a source of energy, typically electric current, hydraulic fluid pressure, or pneumatic pressure, and converts that energy into motion How do actuators work? Linear actuators, hydraulic actuators, pneumatic actuators, and vacuum actuators. Actuators are used in many types of automotive applications, including, but not limited to: power steering, vacuum assist, cruise control, and DRS.
Grounding and Shielding of electric circuits
Covers electromagnetic interference, ground loops, and other topics involving the grounding and shielding of electric circuits. My Patreon account is at https://www.patreon.com/EugeneK
Fourier Transform, Fourier Series, and frequency spectrum
Fourier Series and Fourier Transform with easy to understand 3D animations.
Electricity Basics: "Principles of Electricity" 1945 General Electric; How Electrons Flow in Matter
Support this channel: https://www.patreon.com/jeffquitney Electronics playlist: https://www.youtube.com/playlist?list=PLAA9B0175C3E15B47 more at http://scitech.quickfound.net/ "Breaks down structure of matter into atoms and, by use of conventional symbols, shows the action of electrons within an atom. The principles involved in the flow of current are explained and a volt, ampere and Ohm are defined." Originally a public domain film from the Library of Congress Prelinger Archives, slightly cropped to remove uneven edges, with the aspect ratio corrected, and one-pass brightness-contrast-color correction & mild video noise reduction applied. The soundtrack was also processed with volume normalization, noise reduction, clipping reduction, and/or equalization (the resulting sound, though not perfect, is far less noisy than the original). http://en.wikipedia.org/wiki/Electricity Wikipedia license: http://creativecommons.org/licenses/by-sa/3.0/ Electricity is a general term encompassing a variety of phenomena resulting from the presence and flow of electric charge. These include many easily recognizable phenomena, such as lightning, static electricity, and the flow of electrical current in an electrical wire. In addition, electricity encompasses less familiar concepts such as the electromagnetic field and electromagnetic induction. The word is from the New Latin ēlectricus, "amber-like", coined in the year 1600 from the Greek ήλεκτρον (electron) meaning amber, because electrical effects were produced classically by rubbing amber. In general usage, the word "electricity" adequately refers to a number of physical effects. In a scientific context, however, the term is vague, and these related, but distinct, concepts are better identified by more precise terms: Electric charge: a property of some subatomic particles, which determines their electromagnetic interactions. Electrically charged matter is influenced by, and produces, electromagnetic fields. Electric current: a movement or flow of electrically charged particles, typically measured in amperes. Electric field: an influence produced by an electric charge on other charges in its vicinity. Electric potential: the capacity of an electric field to do work on an electric charge, typically measured in volts. Electromagnetism: a fundamental interaction between the magnetic field and the presence and motion of an electric charge. The most common use of the word "electricity" is less precise. It refers to: Electric power (which can refer imprecisely to a quantity of electrical potential energy or else more correctly to electrical energy per time) that is provided commercially, by the electrical power industry... Electrical phenomena have been studied since antiquity, though advances in the science were not made until the seventeenth and eighteenth centuries. Practical applications for electricity however remained few, and it would not be until the late nineteenth century that engineers were able to put it to industrial and residential use. The rapid expansion in electrical technology at this time transformed industry and society. Electricity's extraordinary versatility as a source of energy means it can be put to an almost limitless set of applications which include transport, heating, lighting, communications, and computation. Electrical power is the backbone of modern industrial society, and is expected to remain so for the foreseeable future... Electric current The movement of electric charge is known as an electric current, the intensity of which is usually measured in amperes. Current can consist of any moving charged particles; most commonly these are electrons, but any charge in motion constitutes a current. By historical convention, a positive current is defined as having the same direction of flow as any positive charge it contains, or to flow from the most positive part of a circuit to the most negative part. Current defined in this manner is called conventional current. The motion of negatively charged electrons around an electric circuit, one of the most familiar forms of current, is thus deemed positive in the opposite direction to that of the electrons. However, depending on the conditions, an electric current can consist of a flow of charged particles in either direction, or even in both directions at once. The positive-to-negative convention is widely used to simplify this situation. The process by which electric current passes through a material is termed electrical conduction... While the particles themselves can move quite slowly, sometimes with an average drift velocity only fractions of a millimetre per second, the electric field that drives them itself propagates at close to the speed of light, enabling electrical signals to pass rapidly along wires.
Views: 47265 Jeff Quitney
nanoHUB-U Bioelectricity L1.3: The Nervous System - Electrical Signals in Cells
Table of Contents: 00:09 Lecture 1.3: Electrical signals in cells 00:20 Week 1: Introduction to the nervous system 00:47 The neuron 01:09 Signal propagation 02:37 Extracellular recording 03:10 Extracellular recording 04:19 Passive conduction 06:48 Passive conduction 08:00 Intracellular recording 09:24 Intracellular recording 09:42 Spatio-temporal summation 11:12 Thresholding 11:55 All or nothing 12:36 Excitatory or inhibitory 13:23 Frequency modulated This video is part of the nanoHUB-U course "Introduction to Bioelectricity." (http://nanohub.org/courses/bioelec) This course introduces students to The fundamentals of bioelectricity of the mammalian nervous system. Passive and active forms of electric signaling in both intra and inter-cellular communication at the atomic, molecular, and engineered device level. Mathematical analysis including the Nernst equation, core conductors, cable theory, and the Hodgkin-Huxley Model of the action potential. Neuromodulation with nano-engineered sensors and actuators.
Views: 6234 nanohubtechtalks
How Computers Work: Binary & Data
You'll hear that everything's "1s and 0s" in a computer, but what does that mean? Find out how computers represent numbers, words, images, and sound. Start learning at http://code.org/ Stay in touch with us! • on Twitter https://twitter.com/codeorg • on Facebook https://www.facebook.com/Code.org • on Instagram https://instagram.com/codeorg • on Tumblr https://blog.code.org • on LinkedIn https://www.linkedin.com/company/code-org • on Google+ https://google.com/+codeorg Help us caption & translate this video! https://amara.org/v/djLv/
Views: 165435 Code.org
What is ELECTRICAL POLARITY? What does ELECTRICAL POLARITY mean? ELECTRICAL POLARITY meaning - ELECTRICAL POLARITY definition - ELECTRICAL POLARITY explanation. Source: Wikipedia.org article, adapted under https://creativecommons.org/licenses/by-sa/3.0/ license. SUBSCRIBE to our Google Earth flights channel - https://www.youtube.com/channel/UC6UuCPh7GrXznZi0Hz2YQnQ Electrical polarity (positive and negative) is the direction of current flow in an electrical circuit. Current flows from the positive pole (terminal) to the negative pole. Electrons flow from negative to positive. In a direct current (DC) circuit, current flows in one direction only, and one pole is always negative and the other pole is always positive. In an alternating current (AC) circuit the two poles alternate between negative and positive and the direction of the current (electron flow) reverses periodically. In DC circuits, the positive pole is usually marked red (or "+") and the negative pole is usually marked black (or "-"), but other color schemes are sometimes used in automotive and telecommunications systems. Polarity symbols are often used where DC is supplied via a coaxial power connector. On a car battery, the positive pole usually has a larger diameter than the negative pole. Modern cars often have a "negative earth" electrical system. In this case the negative terminal of the battery is connected to the vehicle's chassis (the metallic body work) and the positive terminal provides the "live" wire to the various systems. However, some older cars were built with a "positive earth" electrical system, in this case the positive terminal of the battery is bonded to the chassis and the negative terminal for the live. In AC systems the two wires of a circuit alternate polarity many times per second. In electrical power systems, all wires carrying the same instantaneous polarity at any moment will have a common identifying marking scheme, such as wire color. Depending on the conventions used for wiring the power system, the color coding or other marking may also indicate additional properties of the conductor, such as its role as neutral in a power circuit. In a polyphase AC system, identifying the wires belonging to a common phase is important to ensure proper operation of the circuit. Where alternating current circuits are used to carry signals such as audio, polarity is also required to ensure proper function of the system. For example, a set of loudspeakers used for stereo music reproduction will have all device terminals and wiring marked to ensure the same instantaneous polarity, so that the resulting sound produced by each speaker element is in the same phase and add correctly at the listener's ear.
Views: 3649 The Audiopedia
Why 3 Phase AC instead of Single Phase???
Seems we can run pretty much everything on a single-phase AC, then why bother with 3 phases?? [draw closed, see comments] To enter the draw you can either: Become a patron (THANKS!): http://patreon.com/electroboom Or just say yes in the form: https://goo.gl/forms/o1FXePjCpISB1Cbf2 Check my tee-shirts at: http://teespring.com/stores/electroboom Read other articles at: http://www.electroboom.com Follow me on Facebook: http://www.facebook.com/ElectroBOOM Thanks to http://lulzbot.com for the 3D printer. Wife's Cake Shop: www.yummyonie.com Shop's Facebook: https://www.facebook.com/Yummy-Yonie-Cakes-186588238067410/ Thanks to http://CircuitSpecialists.com for proving my essential lab tools My sponsors and patrons, http://www.electroboom.com/?page_id=727 Below are my Super Patrons with support to the extreme! Aki K. at http://www.pc-doctor.com/ Enzo Breda Lee By: Mehdi Sadaghdar
Views: 1482827 ElectroBOOM
How To Eliminate Electrical Noise in Your Signal Path: Tip 4 of 10
http://walkeraudio.com Making the best audio gear in the world is our goal. Electrical noise (EMI and RFI) is a silent killer of great sound - and it's everywhere! Between household lighting, appliances, radio, 3G & 4G data service, WiFi, satellite and OTA TV service, and even the EMI generated by your components themselves, there's a lot to combat to get your system sounding its best. But don't worry - with a few simple steps you can GREATLY improve the sound of your system! For more information on the Eliminator Directional Antennae, visit http://walkeraudio.com/?product=eliminator-directional-antennae For more on the Reference High-Definition Links, visit http://walkeraudio.com/?product=high-definition-links Thanks for watching, and Happy Listening!
Views: 21833 Lloyd Walker
Cardiac Arrhythmias
Cardiac Arrhythmias Overview: Sinus, Atrial and Ventricular Rhythms, Anatomy and ECG, Animation. This video and other related images/videos (in HD) are available for licensing here: https://www.alilamedicalmedia.com/-/galleries/images-videos-by-medical-specialties/cardiology-and-vascular-diseases ©Alila Medical Media. All rights reserved. Voice by: Abbie Drum Support us on Patreon and get FREE downloads and other great rewards: patreon.com/AlilaMedicalMedia All images/videos by Alila Medical Media are for information purposes ONLY and are NOT intended to replace professional medical advice, diagnosis or treatment. Cardiac arrhythmias classified by site of origin: Sinus rhythms, from the SA node; Atrial rhythms the atria; Ventricular rhythms from the ventricles. Sinus bradycardia and sinus tachycardia may be normal or clinical depending on the underlying cause. For example, sinus bradycardia is considered normal during sleep and sinus tachycardia may be normal during physical exercises. Cardiac arrhythmias that originate from other parts of the atria are always clinical. The most common include: atrial flutter, atrial fibrillation and AV nodal re-entrant tachycardia. These are forms of supraventricular tachycardia or SVT. Atrial flutter or A-flutter is caused by an electrical impulse that travels around in a localized self-perpetuating loop, most commonly located in the right atrium. This is called a re-entrant pathway. For each cycle around the loop, there is one contraction of the atria. The atrial rate is regular and rapid - between 250 and 400 beats per minute. Ventricular rate, or heart rate, however, is slower, thanks to the refractory properties of the AV node. The AV node blocks part of atrial impulses from reaching the ventricles. In this example, only one out of every three atrial impulses makes its way to the ventricles. The ventricular rate is therefore 3 times slower than the atrial rate. This is an example of a “3 to 1 heart block”. Ventricular rate in A-flutter is usually regular, but it can also be irregular. On an ECG atrial flutter is characterized by absence of normal P wave. Instead, flutter waves, or f-waves are present in saw-tooth patterns. Atrial fibrillation is caused by multiple electrical impulses that are initiated randomly from many ectopic sites in and around the atria, commonly near the roots of pulmonary veins. These un-synchronized, chaotic electrical signals cause the atria to quiver or fibrillate rather than contract. The atrial rate during atrial fibrillation can be extremely high, but most of the electrical impulses do not pass through the AV node to the ventricles, again, thanks to the refractory properties of the cells of the AV node. Those do come through are irregular. Ventricular rate or heart rate is therefore irregular and can range from slow - less than 60 - to rapid -more than 100 - beats per minute. On an ECG, atrial fibrillation is characterized by absence of P-waves and irregular narrow QRS complexes. The baseline may appear undulating or totally flat depending on the number of ectopic sites in the atria. In general, larger number of ectopic sites results in flatter baseline. AV nodal re-entrant tachycardia or AVNRT is caused by a small re-entrant pathway that involves directly the AV node. Every time the impulse passes through the AV node, it is transmitted down to the ventricles. The atrial rate and ventricular rate are therefore identical. Heart rate is regular and fast, ranging from 150 to 250 beats per minute. Ventricular rhythms are the most dangerous. In fact, they are called lethal rhythms. Ventricular tachycardia or V-tach is most commonly caused by a single strong firing site or circuit in one of the ventricles. It usually occurs in people with structural heart problems such as scarring from a previous heart attack or abnormalities in heart muscles. Impulses starting in the ventricles produce ventricular premature beats that are regular and fast, ranging from 100 to 250 beats per minute. On an ECG V-tach is characterized by wide and bizarre looking QRS complexes. P wave is absent. V-tach may occur in short episodes of less than 30 seconds and cause no or few symptoms. Sustained v-tach lasting for more than 30 seconds requires immediate treatment to prevent cardiac arrest. Ventricular tachycardia may also progress into ventricular fibrillation. Ventricular fibrillation or v-fib is caused by multiple weak ectopic sites in the ventricles. These un-synchronized, chaotic electrical signals cause the ventricles to quiver or fibrillate rather than contract. The heart pumps little or no blood. V-fib can quickly lead to cardiac arrest. V-fib ECG is characterized by irregular random waveforms of varying amplitude, with no identifiable P wave, QRS complex or T wave. Amplitude decreases with time, from initial coarse v-fib to fine v-fib and ultimately to flatline.
Views: 371297 Alila Medical Media
Free Energy Light Bulb Using Wireless Signals With Magnet - Amazing Electric Technology
Free Energy Light Bulb Using Wireless Signals With Magnet - Amazing Electric Technology Please Help Click Subscribe Amazing Tech Channel To Get More New Videos : https://www.youtube.com/channel/UCmrASaBTAO2RlvwRFYCCycg?sub_confirmation=1 Thank you for watching , like , share , comment !
Views: 5751 Amazing Tech
HOW IT WORKS: Morse Code
The basic method is explained for sending messages using a telegraph machine transmitting short and long signals called "dots" and "dashes".
Electric Signal Commutator Built on TDA1029
Electric Signal Commutator Built on TDA1029 Today when developing input switches for amplifier equipment we usually prefer using electric input signal commutators. They are more reliable and easy to control in comparison to the mechanical ones. One of such commutators is the electric input switch. It is based on the TDA1029 microcircuit and is widely used in sound producing equipment. The structure is built on an integrated chip which is an electric switch commutating 4 stereo inputs with 1 stereo output. The signals coming to the inputs of the microcircuit allow using the device within the whole frequency range of up to 1.3 MHz. The optimal supply voltage range is 12 to 20 V at a current consumption of up to 50 mA. To avoid any spurious high-frequency signals at the device's output due to the high bandwidth of the microcircuit you should use RC filters at the commutator's input and capacitive decoupling at the device's output. The structure conveniently fits a small section of a circuit board. For convenience of mounting you can use additional sockets. They can be installed directly onto the circuit board. You can use any type of switch. You can also add an LED indicator of a switched on channel. The output of the commutator is connected to the input of the power amplifier to which the sound signal from the corresponding input of the device comes.
Views: 1614 ChipDipvideo
How do transmission lines work
Mostly we only recognize pylons and cables when we see a transmission line. Our new film explains what is going on between the pylons and what happens when the lightning strikes. www.50hertz.com
Views: 421864 50HertzTransmission
JCB Electrical Explained.
More details visit: http://www.techtrixinfo.com/ Plz Join Our Face Book Page. http://www.facebook.com/pages/TechTrixInfo/271447906234307
Views: 28455 TechTrixInfo
Inductor basics - What is an inductor?
The basics of how inductors work, a demo showing an inductor filtering out high frequency signals, a quick low pass LC filter, and a demo showing the magnetic field created around inductors. Webpage: http://www.afrotechmods.com Twitter: http://twitter.com/Afrotechmods Facebook: http://www.facebook.com/Afrotechmods/
Views: 1405219 Afrotechmods
Transistors, How do they work ?
Dear friends, Please support us at Patreon, so that we can continue our free educational service https://www.patreon.com/LearnEngineering The invention of transistors revolutionized human civilization like no other technology. This video demonstrates working of a Bipolar Junction Transistor (BJT) with it's practical applications such as transistor as an amplifier and as a switch with help of animation. Along with transistor working of diode is also explained in the video. The video covers following topics - structure of Silicon atom, doping, N type doping, P type doping, working of Diode, working of NPN transistor and dual stage amplification. Like us on FB : https://www.facebook.com/LearnEngineering Voice-over artist : https://www.fiverr.com/mikepaine
Views: 4375389 Learn Engineering
AM and FM Radio As Fast As Possible
AM & FM radio have been around since way before the digital age. How can radios decode AM & FM signals only using analog technology? Freshbooks message: Head over to http://freshbooks.com/techquickie and don’t forget to enter Tech Quickie in the “How Did You Hear About Us” section when signing up for your free trial. Follow: http://twitter.com/linustech Join the community: http://linustechtips.com
Views: 434952 Techquickie
Neuron action potential - physiology
What is a neuron action potential? Neurons use ions and electrical charges to relay signals from one neuron to the next, called an action potential. Find more videos at http://osms.it/more. Hundreds of thousands of current & future clinicians learn by Osmosis. We have unparalleled tools and materials to prepare you to succeed in school, on board exams, and as a future clinician. Sign up for a free trial at http://osms.it/more. Subscribe to our Youtube channel at http://osms.it/subscribe. Get early access to our upcoming video releases, practice questions, giveaways, and more when you follow us on social media: Facebook: http://osms.it/facebook Twitter: http://osms.it/twitter Instagram: http://osms.it/instagram Our Vision: Everyone who cares for someone will learn by Osmosis. Our Mission: To empower the world’s clinicians and caregivers with the best learning experience possible. Learn more here: http://osms.it/mission Medical disclaimer: Knowledge Diffusion Inc (DBA Osmosis) does not provide medical advice. Osmosis and the content available on Osmosis's properties (Osmosis.org, YouTube, and other channels) do not provide a diagnosis or other recommendation for treatment and are not a substitute for the professional judgment of a healthcare professional in diagnosis and treatment of any person or animal. The determination of the need for medical services and the types of healthcare to be provided to a patient are decisions that should be made only by a physician or other licensed health care provider. Always seek the advice of a physician or other qualified healthcare provider with any questions you have regarding a medical condition.
Views: 174689 Osmosis
Signal Transduction Pathways
038 - Signal Transduction Pathways.mov Paul Andersen explains how signal transduction pathways are used by cells to convert chemical messages to cellular action. Epinephrine is used as a sample messenger to trigger the release of glucose from cells in the liver. The G-Protein, adenylyl cyclase, cAMP, and protein kinases are all used as illustrative examples of signal transduction. A review of the concepts is also included. Do you speak another language? Help me translate my videos: http://www.bozemanscience.com/translations/ Intro Music Atribution Title: I4dsong_loop_main.wav Artist: CosmicD Link to sound: http://www.freesound.org/people/CosmicD/sounds/72556/ Creative Commons Atribution License All of the images are licensed under creative commons and public domain licensing: "File:Dora and Boots.jpg." Wikipedia, the Free Encyclopedia, October 28, 2013. http://en.wikipedia.org/w/index.php?title=File:Dora_and_Boots.jpg&oldid=468219594. "File:Jimi Hendrix 1967 Uncropped.jpg." Wikipedia, the Free Encyclopedia. Accessed December 9, 2013. http://en.wikipedia.org/wiki/File:Jimi_Hendrix_1967_uncropped.jpg. "File:MarshallStack Slayer.jpg." Wikipedia, the Free Encyclopedia. Accessed December 9, 2013. http://en.wikipedia.org/wiki/File:MarshallStack_Slayer.jpg. "File:Pickup-SSH.jpg." Wikipedia, the Free Encyclopedia. Accessed December 9, 2013. http://en.wikipedia.org/wiki/File:Pickup-SSH.jpg. Juancoronado1974. English: Phospholipid Bilayer, November 23, 2013. Own work. http://commons.wikimedia.org/wiki/File:Bilayer.png.
Views: 989537 Bozeman Science
3/24/2015 -- WIRELESS POWER using MICROWAVES -- Japan moving forward on new plans
Another huge developing technology story regarding microwaves and next generation applied uses of frequency. Japan has announced they are moving forward with a microwave wireless power system. Full website post with links and more information on wireless power, specs + diagrams of the components, and how to build one yourself. All links shown in the video are contained here: http://dutchsinse.com/3232015-japan-moves-forward-on-wireless-power-using-microwaves-sps-coming-soon/ See the Boeing force field using microwaves here: https://www.youtube.com/watch?v=VjJlt_0I-KY _____ The system has now been tested in the Laboratory to ensure that it works, the next step is to build a space based version which beams microwaves back to Earth, which are then converted to DC power ! This link contains a full description plus basic diagrams to build your own version. Of course there are possibly VERY HIGH VOLTAGE conditions, so if you build one, be extremely careful, and know what you're doing before beginning assembly. _____ Earlier today, breaking news was announced in regards to another use of Microwaves. Boeing aircraft company has patented MICROWAVE force fields which reflect / stop incoming shockwaves from explosions. Literally a plasma shield which will stop a blast from a bomb. The plasma is generated using microwaves from two transmitters. ______ The use of the 2GHz band, and now the use of the 5GHz band shows that professionals already know the potential for electrical conversion is there. Per the US FCC rules, the average exposure to microwaves contains about 61 volts per sq. meter. Meaning the potential voltage available MUST be somewhere near (or above) 61 volts every 3 sq. feet. already around us currently. This does not count the FM, AM, Shortwave, High frequency, VHF,and other UHF signals already coming in to our houses from every source imaginable. If you had a series of different sized antennas, you could theoretically "listen" to multiple bands, and convert all the bands power into DC.. not just microwaves. The great thing about building your own system, is that we are already exposed to 2.4GHz wifi, 2.4GHz bluetooth, 2.7GHz NEXRAD RADAR, 1GHz television, FM, AM and other bands. No harmful effects of LISTENING... just like listening to a radio, you and I could stand right next to each other and both pick up a signal, and convert the power with no effect on the signal. Just like listening to a radio... when the wave is sent out from the radio station... it goes out in all directions.. your antenna picks up the wave, and converts it into sound waves. Instead of converting the radio waves into Sound waves out of a speaker, you convert the radio waves to DC power. It does NOT suck in radio waves, thus there is no loss to the people already beaming out the signal. For instance... mobile phone companies are sending out near 2.4GHz in some cases from cell phone towers... you could pick up that general frequency, and convert it to DC without them ever knowing, or experiencing loss.. and technically the actual "power" isn't coming from them.. just the frequency.... :) ______
Views: 259674 dutchsinse
Prof. Raj Nadakuditi - Signals and Noise
Prof. Nadakuditi's research involves statistical signal processing, random matrix theory, random graphs and light transport through opaque random media. He knows how to find the smallest signals with meaning buried in other random information.
Bring the body's electrical signals out of the body: Tim Marzullo at TEDxWayPublicLibrary
If neuroscience gives you a headache, you must be doing it wrong. Timothy Marzullo, neuroscientist and co-founder of Backyard Brains, describes his fascinating work on making do-it-yourself-neuroscience tools, complete with live demonstrations. In the spirit of ideas worth spreading, TEDx is a program of local, self-organized events that bring people together to share a TED-like experience. At a TEDx event, TEDTalks video and live speakers combine to spark deep discussion and connection in a small group. These local, self-organized events are branded TEDx, where x = independently organized TED event. The TED Conference provides general guidance for the TEDx program, but individual TEDx events are self-organized.* (*Subject to certain rules and regulations)
Views: 2085 TEDx Talks
Basic Electrical Engineering | Module 3 | Phase Sequence  (Lecture 21)
Subject --- Basic Electrical Engineering Topic --- Phase Sequence (Lecture 21) Faculty --- Ranjan Rai GATE Academy Plus is an effort to initiate free online digital resources for the first time in India and particularly Mr. Umesh Dhande, Founder and Director of GATE ACADEMY creative in order to shape the best career of Engineering student approaching to B.Tech/B.E. courses. Check out our facebook page for more details. https://www.facebook.com/GATE.ACADEMY.PLUS Watch out the below mentioned playlists for other videos on these subjects : 1. Analog Electronics --- https://bit.ly/2IEFMq5 2. Basic Electrical Engineering --- https://bit.ly/2MuVK8c 3. Electronic Devices & Circuits --- https://bit.ly/2NcEBBF 4. Engineering Graphics --- https://bit.ly/2IEGRhD 5. Engineering Mathematics --- https://bit.ly/2tSsOzt 6. Exclusive --- https://bit.ly/2KAw0XM 7. Fluid Mechanics --- https://bit.ly/2tHaQRk 8. Signals and Systems --- https://bit.ly/2Khihsy 9. Thermodynamics --- https://bit.ly/2PlxJ5O 10. Strength of Materials --- https://bit.ly/2QGn0Tr 11. Doubt Clearing Session --- https://bit.ly/2QEXcqY 12. It's Complicated --- https://bit.ly/2CCg3jx
Action Potential in Neurons, Animation.
What is Action Potential? How is it Generated in Neuron? Clear and Concise Explanation of Phases. This video and other related images/videos (in HD) are available for instant download licensing here : https://www.alilamedicalmedia.com/-/galleries/images-videos-by-medical-specialties/neurology ©Alila Medical Media. All rights reserved. Support us on Patreon and get FREE downloads and other great rewards: patreon.com/AlilaMedicalMedia Cells are polarized, meaning there is an electrical voltage across the cell membrane. In a resting neuron, the typical voltage, known as the RESTING membrane potential, is about -70mV (millivolts). The negative value means the cell is more negative on the INSIDE. At this resting state, there are concentration gradients of sodium and potassium across the cell membrane: more sodium OUTSIDE the cell and more potassium INSIDE the cell. These gradients are maintained by the sodium-potassium pump which constantly brings potassium IN and pumps sodium OUT of the cell. A neuron is typically stimulated at dendrites and the signals spread through the soma. Excitatory signals at dendrites open LIGAND-gated sodium channels and allow sodium to flow into the cell. This neutralizes some of the negative charge inside the cell and makes the membrane voltage LESS negative. This is known as depolarization as the cell membrane becomes LESS polarized. The influx of sodium diffuses inside the neuron and produces a current that travels toward the axon hillock. If the summation of all input signals is excitatory and is strong enough when it reaches the axon hillock, an action potential is generated and travels down the axon to the nerve terminal. The axon hillock is also known as the cell’s “trigger zone” as this is where action potentials usually start. This is because action potentials are produced by VOLTAGE-gated ion channels that are most concentrated at the axon hillock. Voltage-gated ion channels are passageways for ions in and out of the cell, and as their names suggest, are regulated by membrane voltage. They open at some values of the membrane potential and close at others. For an action potential to be generated, the signal must be strong enough to bring the membrane voltage to a critical value called the THRESHOLD, typically about -55mV. This is the minimum required to open voltage-gated ion channels. At threshold, sodium channels open quickly. Potassium channels also open but do so more slowly. The initial effect is therefore due to sodium influx. As sodium ions rush into the cell, the inside of the cell becomes more positive and this further depolarizes the cell membrane. The increasing voltage in turn causes even more sodium channels to open. This positive feedback continues until all the sodium channels are open and corresponds to the rising phase of the action potential. Note that the polarity across the cell membrane is now reversed. As the action potential nears its peak, sodium channels begin to close. By this time, the slow potassium channels are fully open. Potassium ions rush out of the cell and the voltage quickly returns to its original resting value. This corresponds to the falling phase of the action potential. Note that sodium and potassium have now switched places across the membrane. As the potassium gates are also slow to close, potassium continues to leave the cell a little longer resulting in a negative overshoot called hyper-polarization. The resting membrane potential is then slowly restored thanks to diffusion and the sodium-potassium pump. During and shortly after an action potential is generated, it is impossible or very difficult to stimulate that part of the membrane to fire again. This is known as the REFRACTORY period. The refractory period is divided into absolute refractory and relative refractory. The absolute refractory period lasts from the start of an action potential to the point the voltage first returns to the resting membrane value. During this time, the sodium channels are open and subsequently INACTIVATED while closing and thus unable to respond to any new stimulation. The relative refractory period lasts until the end of hyper-polarization. During this time, some of the potassium channels are still open, making it difficult for the membrane to depolarize, and a much stronger signal is required to induce a new response. During an action potential, the sodium influx at a point on the axon spreads along the axon, depolarizing the adjacent patch of the membrane, generating a similar action potential in it. The sodium currents diffuse in both directions on the axon, but the refractory properties of ion channels ensure that action potential propagates ONLY in ONE direction. This is because ONLY the unfired patch of the axon can respond with an action potential; the part that has just fired is unresponsive until the action potential is safely out of range.
Views: 378849 Alila Medical Media
Lecture - 11 The Graph Theory Approach for Electrical Circuits(Part-I)
Lecture series on Dynamics of Physical System by Prof. Soumitro Banerjee, Department of Electrical Engineering, IIT Kharagpur.For more details on NPTEL visit http://nptel.iitm.ac.in
Views: 211035 nptelhrd
What is ELECTRICAL NETWORK? What does ELECTRICAL NETWORK mean? ELECTRICAL NETWORK meaning. Source: Wikipedia.org article, adapted under https://creativecommons.org/licenses/by-sa/3.0/ license. An electrical network is an interconnection of electrical components (e.g. batteries, resistors, inductors, capacitors, switches) or a model of such an interconnection, consisting of electrical elements (e.g. voltage sources, current sources, resistances, inductances, capacitances). An electrical circuit is a network consisting of a closed loop, giving a return path for the current. Linear electrical networks, a special type consisting only of sources (voltage or current), linear lumped elements (resistors, capacitors, inductors), and linear distributed elements (transmission lines), have the property that signals are linearly superimposable. They are thus more easily analyzed, using powerful frequency domain methods such as Laplace transforms, to determine DC response, AC response, and transient response. A resistive circuit is a circuit containing only resistors and ideal current and voltage sources. Analysis of resistive circuits is less complicated than analysis of circuits containing capacitors and inductors. If the sources are constant (DC) sources, the result is a DC circuit. A network that contains active electronic components is known as an electronic circuit. Such networks are generally nonlinear and require more complex design and analysis tools.
Views: 999 The Audiopedia