CELLULAR NEUROPHYSIOLOGY CONSTANCE HAMMOND
|
|
- Audra Ryan
- 6 years ago
- Views:
Transcription
1 CELLULAR NEUROPHYSIOLOGY CONSTANCE HAMMOND Chapter 1 Zoom in on Patch configurations In the jargon of electrophysiologists, a patch is a piece of neuronal membrane. Researchers invented a technique known as a patch-clamp, which records the current through a single ion channel, some ion channels or through all open ion channels in the neuron membrane. To obtain these recordings, researchers use different patch configurations. We'll explain here only the three configurations used in the course: the cell-attached configuration, the whole-cell configuration, and the "outside-out" excised patch configuration. According to the type of recording to perform, a particular type of configuration will be chosen: 1. to record a unitary current: cell-attached or outside-out configuration; 2. to record a total current: whole-cell configuration; 3. to record changes in membrane potential (action potentials or postsynaptic potentials): whole-cell configuration.
2 The cell-attached configuration (attached to the pipette - Figure a) First, the pipette is filled with an extracellular fluid. Positive pressure is applied in the electrode by means of a syringe connected to the electrode, so that the intrapipette fluid tends to leave the pipette. The electrode is then brought near to the soma of a neuron. When the electrode touches the membrane, the positive pressure is withdrawn to draw the membrane toward the mouth of the pipette. We wait without moving the pipette; a seal is made between the walls of the pipette and the soma membrane. This seal strength can be measured by applying a low level of amplitude current in the pipette. Since V = RI, one can measure the resistance of the seal. If a step ΔV (in mv) is applied through the pipette, the recorded response is a change in the current ΔI (in pa), such that ΔV = R ΔI. This allows us to calculate R (in GΩ), the seal resistance. In order for the seal to be perfect it is necessary that the resistance of the seal is on the order of gigaohms (10 9 Ohms = 1 GΩ). Thus, the neuron membrane is sealed to the mouth of the pipette. The pipette can be placed at the soma and also at a dendrite. The cell-attached configuration in voltage-clamp mode records the unit current through one or more open channels in the patch of membrane underneath the pipette mouth. The intracellular medium of the neuron is its physiological medium. Recording a total current: whole-cell configuration (Figure b) The whole-cell configuration means that the recording electrode is continuous with the entire membrane of the neuron. To accomplish this, the pipette is filled with an artificial intracellular solution that will become the intracellular medium of the neuron (i). We start from a cellattached configuration with a seal on the order of GΩ. Then, suction is applied to the interior of the pipette (negative pressure) for attracting the small piece of membrane which plugs the opening of the pipette towards the interior of the pipette. We know that this piece of membrane has been removed from the pipette opening because the access resistance is much lower (the pipette is no longer plugged). In the whole-cell configuration, the intrapipette solution gradually replaces the intracellular medium. This voltage-clamp mode configuration records the current passing through all open ion channels in the neuronal membrane, i.e. a total current is recorded. In current-clamp mode, this measures changes in potential across the entire neuronal membrane, i.e. action potentials or postsynaptic potentials are recorded (seen in upcoming chapters). The pipette can be placed at the soma, and also at a dendrite. The outside-out configuration (Figure c) The outside-out configuration means that the recording electrode records the activity of a small piece of membrane whose external side is in contact with the artificial extracellular solution. When we want to record a channel situated in a piece of somatic membrane, everything begins exactly as for a whole-cell configuration. Once this configuration is obtained, the pipette is gently lifted in order to stretch the membrane of the soma (Figure c). At one point a piece will detach and close in on itself. We know that the excised patch configuration has been achieved because the membrane resistance becomes very low. An outside-out patch can also be obtained at the dendritic membrane. This configuration records the unitary current traversing a single channel in voltage-clamp mode. Compared to the cellattached configuration, the outside-out configuration enables researchers to change the MOOC Cellular neurophysiology Ch.1 Zoom 2/8
3 intracellular medium of the neuron and to easily add pharmacological agents into the extracellular medium. In summary In both whole-cell and outside-out configurations, the intracellular medium is the intrapipette environment and the extracellular environment is the bath medium. Neither of the two media is the actual medium of the recorded neurons. In the cell-attached configuration, the intracellular medium remains intact and the extracellular medium is the bath medium. Voltage-clamp/current-clamp There are two major recording modes for neuronal activity: voltage-clamp mode and currentclamp mode. The experimenter chooses one or the other mode depending on what he wants to measure: measurement of current in voltage-clamp mode, and measurement of the changes in potential in current-clamp mode. In voltage-clamp mode, the total membrane potential (whole-cell configuration) or a small piece of membrane (cell-attached or outside-out configurations) is kept constant at a value set by the experimenter, called VH (V for Potential and H for Hold ). To maintain this potential, during the recording, any change in the recorded value from the set VH value is immediately compensated by the injection of a positive or negative current through the recording electrode. It's like constantly adding more water into a leaky vessel so that the water level stays the same. The voltage-clamp mode measures I (current across the entire neuronal membrane) or i (current crossing an ion channel), depending on the selected patch configuration. Changes in I or i will then depend only on G or γ (total or unitary conductance) according to the formula I = GVH, where i = γv H. In current-clamp mode, the experimenter measures variations in the membrane potential. In this mode, the value of the current injected through the electrode is selected by the experimenter. Depolarization, hyperpolarization, repolarization The reference point for changes in membrane potential is often the resting potential (in current-clamp recordings) or the holding membrane potential (in voltage-clamp recordings). A depolarization is a change in potential towards potentials less hyperpolarized than the resting or holding membrane potential. For example, if the membrane changes from -60 to - 40 mv, it is said to depolarize. MOOC Cellular neurophysiology Ch.1 Zoom 3/8
4 It also depolarizes if it changes from -60 mv to +20 mv. A hyperpolarization is a change in potential towards potentials more hyperpolarized than the resting or holding membrane potential. For example, if the membrane changes from -60 to - 80 mv, it is said to hyperpolarize. A repolarization is a return to the resting or holding membrane potential. From a depolarized value, the membrane gets repolarized by hyperpolarizing. From a hyperpolarized value, the membrane gets repolarized by depolarizing. The Nernst equation gives the equilibrium potential of an ion The direction of the passive transport of an ion species depends on its concentration on both sides of the membrane: ions move passively from the medium where they are more concentrated towards the medium where they are less concentrated. Because ions are charged molecules, their direction of passive transport through the membrane also depends on the membrane potential (Vm = Vi Vo): negatively-charged ions are attracted to the + side of the membrane and vice versa. When ion concentrations are constant, the only variable is the membrane potential, which changes depending on the signals received by the neuron. Thus, the passage of an ion can change direction, depending on Vm. Take Na + ions from the above diagram as an example. MOOC Cellular neurophysiology Ch.1 Zoom 4/8
5 Loot at their concentration gradient (red arrow): the concentration of Na + ions is higher outside than inside. Thus, Na + ions tend to enter the neuron through the open Na + channels. Now consider their electrical gradient (green arrow): the internal side of the membrane is more negatively charged than the external side. This also attracts the Na + ions inside the neuron. Overall, the net flux of Na + ions is therefore inward (blue arrow): positively-charged Na + ions tend to move inside the neuron. But when Vm is reversed during the action potential, what are the Na + ions doing? In the second diagram, we see that, while the magnitude of the concentration gradient remains the same, the direction of the electrical gradient has reversed. How does it then affect the flow of Na + ions? To solve this problem, we must quantify the above situation. The Nernst equation gives the equilibrium potential of an ion (Eion). The definition of equilibrium potential is as follows: when Vm = Eion, the net flow of this ion is zero. When Vm = Eion, this ion is in equilibrium. It is around this Eion equilibrium potential that the net flow of this ion is reversed. where: R is the gas constant, T is the absolute temperature in K, z is the valence of the ion, F is Faraday's constant. In other words: MOOC Cellular neurophysiology Ch.1 Zoom 5/8
6 For Na + ions, at the given concentrations, ENa = 58/1 log(140/14) = +58 mv As long as Vm is more hyperpolarized than +58 mv, Na + ions passively enter the neurons through the open Na + channels. As Vm never reaches +58 mv, we can say that Na + ions always enter passively into the neurons, but with a variable force (compare the blue arrows between the two figures): What is the situation for other ionic species? You can verify that K + ions always passively exit through open K + channels, knowing that [K + ]o = 3 mm and [K + ]i = 140 mm. The situation is much more complicated for chloride ions. This will be explained in chapter 5 (GABAergic synaptic transmission). Resting membrane potential When recording the membrane potential in the whole-cell configuration and in current-clamp mode, we see there is a potential difference between the two sides of the membrane, so that the internal side is more negatively charged than the external side. This is true for all living cells. Definition : the resting potential is the membrane potential of a neuron when it is not transmitting action potentials. It varies from one neuron to another, but it is always negative, on the order of -80 to -50 mv. How is the resting potential measured? We measure the difference in potential between the pipette (which measures Vi) and the "ground", another electrode which is immersed in the extracellular medium. We can also measure the difference in potential between the two sides of the membrane, Vi and Vo. Ionic mechanisms underlying the resting potential MOOC Cellular neurophysiology Ch.1 Zoom 6/8
7 If only K + channels are open in the membrane, then K + ions will exit until the membrane potential reaches E K (EK = -90 mv approximately). At this potential, there are as many K + ions that exit as K + ions that enter. It is a steady state. The membrane potential will stabilize at this value as long as other types of ion channels do not open. However, we see very often that the resting potential is more depolarized than EK, by about mv (Vresting = -60 mv). There are always some Na + channels and some cation channels (Na/K) open at the resting potential. Na + ions thus enter in neurons at rest and tend to change the membrane potential towards E cations and ENa (i.e., to about -30 mv and +60 mv), much more depolarized values than the EK. That s why the resting membrane has a potential between EK and ENa, but closer to EK than ENa, because, at these hyperpolarized potentials, a lot more K + channels are open than channels only permeable to Na +. Depending on the proportion of open K + channels compared to Na + and cationic channels, the resting potential has more or less hyperpolarized values. For example, striatal neurons, in the central nervous system, have a resting potential near -80 mv, because their membrane contains a high proportion of K + channels open in this range of potentials. Other neurons have a resting potential near -60 mv, or even -50 mv, because the ratio of open K + channels to Na + channels is different. What types of channels are open at the resting potential? For a long time, these were known as "leakage channels", suggesting that these channels are insensitive to any factor. In fact, these channels can be voltage-dependent, but are open in this range of hyperpolarized potentials. There are also K + channels sensitive to chemical factors (oxygen tension, ph), biochemical factors (G proteins), and mechanical factors (stretching of the membrane), etc. To call them leakage channels is not correct, because it suggests that they are "protein-holes" in the membrane that are not subject to any regulation. MOOC Cellular neurophysiology Ch.1 Zoom 7/8
8 In summary, the resting potential of a neuron has a value that does not correspond exactly to EK (although it is close), nor to Ecations, nor to ENa. Its value depends on the proportion of K +, Na + and cationic channels open in these ranges of hyperpolarized potentials expressed by the neuron. However, for some neurons which are continuously active, this notion of a resting potential (i.e., a stable membrane potential in the idle state) is an abstract notion: their membrane passes through periods of inactivity very briefly, during which their membrane potential is unstable. For these neurons, it is very difficult to measure a resting potential. Inward current and outward current A current is a flow of charges. In biology, a current is a flow of ions. By definition, "inward or outward current" means "inward current of + charges or outward current of + charges." Positive charges going from the external medium to the internal medium of a neuron, or negative charges going in the opposite direction, create an inward current. For example, the entry of Na + ions through Na + channels is an inward current (Figure a). Similarly, exit of Cl - ions through GABAA channels is an inward current. By convention, an inward current is negative: we represent it going from 0 pa towards negative values (Figure a). Conversely, an outward current is positive: we represent it going from 0 pa towards positive values, (Figure b). Thus, a Na + current will have a negative value (- 15 pa, for example) while a K + current will have a positive value (for example, +20 pa). MOOC Cellular neurophysiology Ch.1 Zoom 8/8
Chapter 1 subtitles Ion gradients
CELLULAR NEUROPHYSIOLOGY CONSTANCE HAMMOND Chapter 1 subtitles Ion gradients Introduction In this first chapter, I'll explain the basic knowledge required to understand the electrical signals generated
More informationRahaf Nasser mohammad khatatbeh
7 7... Hiba Abu Hayyeh... Rahaf Nasser mohammad khatatbeh Mohammad khatatbeh Brief introduction about membrane potential The term membrane potential refers to a separation of opposite charges across the
More informationChannels can be activated by ligand-binding (chemical), voltage change, or mechanical changes such as stretch.
1. Describe the basic structure of an ion channel. Name 3 ways a channel can be "activated," and describe what occurs upon activation. What are some ways a channel can decide what is allowed to pass through?
More informationNeuroPhysiology and Membrane Potentials. The Electrochemical Gradient
NeuroPhysiology and Membrane Potentials Communication by neurons is based on changes in the membrane s permeability to ions This depends on the presence of specific membrane ion channels and the presence
More informationPhysiology Unit 2. MEMBRANE POTENTIALS and SYNAPSES
Physiology Unit 2 MEMBRANE POTENTIALS and SYNAPSES Neuron Communication Neurons are stimulated by receptors on dendrites and cell bodies (soma) Ligand gated ion channels GPCR s Neurons stimulate cells
More information- the flow of electrical charge from one point to the other is current.
Biology 325, Fall 2004 Resting membrane potential I. Introduction A. The body and electricity, basic principles - the body is electrically neutral (total), however there are areas where opposite charges
More informationParticles with opposite charges (positives and negatives) attract each other, while particles with the same charge repel each other.
III. NEUROPHYSIOLOGY A) REVIEW - 3 basic ideas that the student must remember from chemistry and physics: (i) CONCENTRATION measure of relative amounts of solutes in a solution. * Measured in units called
More informationLESSON 2.2 WORKBOOK How do our axons transmit electrical signals?
LESSON 2.2 WORKBOOK How do our axons transmit electrical signals? This lesson introduces you to the action potential, which is the process by which axons signal electrically. In this lesson you will learn
More informationNeurophysiology. Danil Hammoudi.MD
Neurophysiology Danil Hammoudi.MD ACTION POTENTIAL An action potential is a wave of electrical discharge that travels along the membrane of a cell. Action potentials are an essential feature of animal
More informationQuantitative Electrophysiology
ECE 795: Quantitative Electrophysiology Notes for Lecture #1 Wednesday, September 13, 2006 1. INTRODUCTION TO EXCITABLE CELLS Historical perspective: Bioelectricity first discovered by Luigi Galvani in
More informationMembrane Potential Fox Chapter 6 pt 2
Vert Phys PCB3743 Membrane Potential Fox Chapter 6 pt 2 T. Houpt, Ph.D. Resting Membrane potential (V m ) or RMP Many cells have a membrane potential (Vm) that can be measured from an electrode in the
More informationPNS Chapter 7. Membrane Potential / Neural Signal Processing Spring 2017 Prof. Byron Yu
PNS Chapter 7 Membrane Potential 18-698 / 42-632 Neural Signal Processing Spring 2017 Prof. Byron Yu Roadmap Introduction to neuroscience Chapter 1 The brain and behavior Chapter 2 Nerve cells and behavior
More informationIonic gradients, membrane potential and ionic currents Constance Hammond
C H A P T E R 3 c0015 Ionic gradients, membrane potential and ionic currents Constance Hammond O U T L I N E u0010 u0015 u0020 3.1 There is an unequal distribution of ions across neuronal plasma membrane.
More informationOverview Organization: Central Nervous System (CNS) Peripheral Nervous System (PNS) innervate Divisions: a. Afferent
Overview Organization: Central Nervous System (CNS) Brain and spinal cord receives and processes information. Peripheral Nervous System (PNS) Nerve cells that link CNS with organs throughout the body.
More informationPhysiology Unit 2. MEMBRANE POTENTIALS and SYNAPSES
Physiology Unit 2 MEMBRANE POTENTIALS and SYNAPSES In Physiology Today Ohm s Law I = V/R Ohm s law: the current through a conductor between two points is directly proportional to the voltage across the
More informationNeurons. The Molecular Basis of their Electrical Excitability
Neurons The Molecular Basis of their Electrical Excitability Viva La Complexity! Consider, The human brain contains >10 11 neurons! Each neuron makes 10 3 (average) synaptic contacts on up to 10 3 other
More informationQuantitative Electrophysiology
ECE 795: Quantitative Electrophysiology Notes for Lecture #1 Tuesday, September 18, 2012 1. INTRODUCTION TO EXCITABLE CELLS Historical perspective: Bioelectricity first discovered by Luigi Galvani in 1780s
More informationIonic basis of the resting membrane potential. Foundations in Neuroscience I, Oct
Ionic basis of the resting membrane potential Foundations in Neuroscience I, Oct 3 2017 The next 4 lectures... - The resting membrane potential (today) - The action potential - The neural mechanisms behind
More informationStructure and Measurement of the brain lecture notes
Structure and Measurement of the brain lecture notes Marty Sereno 2009/2010!"#$%&'(&#)*%$#&+,'-&.)"/*"&.*)*-'(0&1223 Neurons and Models Lecture 1 Topics Membrane (Nernst) Potential Action potential/voltage-gated
More informationCells have an unequal distribution of charge across their membrane: more postiive charges on the outside; more negative charges on the inside.
Resting Membrane potential (V m ) or RMP Many cells have a membrane potential (Vm) that can be measured from an electrode in the cell with a voltmeter. neurons, muscle cells, heart cells, endocrine cells...
More informationAction Potential Propagation
Action Potential Propagation 2 Action Potential is a transient alteration of transmembrane voltage (or membrane potential) across an excitable membrane generated by the activity of voltage-gated ion channels.
More informationMembrane Potentials, Action Potentials, and Synaptic Transmission. Membrane Potential
Cl Cl - - + K + K+ K + K Cl - 2/2/15 Membrane Potentials, Action Potentials, and Synaptic Transmission Core Curriculum II Spring 2015 Membrane Potential Example 1: K +, Cl - equally permeant no charge
More informationCh 8: Neurons: Cellular and Network Properties, Part 1
Developed by John Gallagher, MS, DVM Ch 8: Neurons: Cellular and Network Properties, Part 1 Objectives: Describe the Cells of the NS Explain the creation and propagation of an electrical signal in a nerve
More informationCellular Electrophysiology. Cardiac Electrophysiology
Part 1: Resting and Action Potentials Cardiac Electrophysiology Theory Simulation Experiment Scale The membrane: structure, channels and gates The cell: resting potential, whole cell currents, cardiac
More informationLojayn Salah. Zaid R Al Najdawi. Mohammad-Khatatbeh
7 Lojayn Salah Zaid R Al Najdawi Mohammad-Khatatbeh Salam everyone, I made my best to make this sheet clear enough to be easily understood let the party begin :P Quick Revision about the previous lectures:
More informationThe Nervous System and the Sodium-Potassium Pump
The Nervous System and the Sodium-Potassium Pump 1. Define the following terms: Ion: A Student Activity on Membrane Potentials Cation: Anion: Concentration gradient: Simple diffusion: Sodium-Potassium
More informationSignal processing in nervous system - Hodgkin-Huxley model
Signal processing in nervous system - Hodgkin-Huxley model Ulrike Haase 19.06.2007 Seminar "Gute Ideen in der theoretischen Biologie / Systembiologie" Signal processing in nervous system Nerve cell and
More informationResting membrane potential,
Resting membrane potential Inside of each cell is negative as compared with outer surface: negative resting membrane potential (between -30 and -90 mv) Examination with microelectrode (Filled with KCl
More informationلجنة الطب البشري رؤية تنير دروب تميزكم
1) Hyperpolarization phase of the action potential: a. is due to the opening of voltage-gated Cl channels. b. is due to prolonged opening of voltage-gated K + channels. c. is due to closure of the Na +
More informationTitle: Membrane Potentials Subtitle: Ion Movement: Forces and Measurement Diomedes E. Logothetis, Ph.D. Lecture goals:
Title: Membrane Potentials Subtitle: Ion Movement: Forces and Measurement Diomedes E. Logothetis, Ph.D. Lecture goals: This lecture will discuss the chemical and electrical forces determining the direction
More information2002NSC Human Physiology Semester Summary
2002NSC Human Physiology Semester Summary Griffith University, Nathan Campus Semester 1, 2014 Topics include: - Diffusion, Membranes & Action Potentials - Fundamentals of the Nervous System - Neuroanatomy
More informationSupplementary Figure 1
Supplementary Figure 1 Activation of P2X2 receptor channels in symmetric Na + solutions only modestly alters the intracellular ion concentration. a,b) ATP (30 µm) activated P2X2 receptor channel currents
More informationGeneral Physics. Nerve Conduction. Newton s laws of Motion Work, Energy and Power. Fluids. Direct Current (DC)
Newton s laws of Motion Work, Energy and Power Fluids Direct Current (DC) Nerve Conduction Wave properties of light Ionizing Radiation General Physics Prepared by: Sujood Alazzam 2017/2018 CHAPTER OUTLINE
More informationBIOELECTRIC PHENOMENA
Chapter 11 BIOELECTRIC PHENOMENA 11.3 NEURONS 11.3.1 Membrane Potentials Resting Potential by separation of charge due to the selective permeability of the membrane to ions From C v= Q, where v=60mv and
More informationAction Potential (AP) NEUROEXCITABILITY II-III. Na + and K + Voltage-Gated Channels. Voltage-Gated Channels. Voltage-Gated Channels
NEUROEXCITABILITY IIIII Action Potential (AP) enables longdistance signaling woohoo! shows threshold activation allornone in amplitude conducted without decrement caused by increase in conductance PNS
More informationLecture 10 : Neuronal Dynamics. Eileen Nugent
Lecture 10 : Neuronal Dynamics Eileen Nugent Origin of the Cells Resting Membrane Potential: Nernst Equation, Donnan Equilbrium Action Potentials in the Nervous System Equivalent Electrical Circuits and
More informationSupratim Ray
Supratim Ray sray@cns.iisc.ernet.in Biophysics of Action Potentials Passive Properties neuron as an electrical circuit Passive Signaling cable theory Active properties generation of action potential Techniques
More informationElectrical Properties of the Membrane
BIOE 2520 Electrical Properties of the Membrane Reading: Chapter 11 of Alberts et al. Stephen Smith, Ph.D. 433 Biotech Center shs46@pitt.edu Permeability of Lipid membrane Lipid bilayer is virtually impermeable
More informationFundamentals of the Nervous System and Nervous Tissue
Chapter 11 Part B Fundamentals of the Nervous System and Nervous Tissue Annie Leibovitz/Contact Press Images PowerPoint Lecture Slides prepared by Karen Dunbar Kareiva Ivy Tech Community College 11.4 Membrane
More informationBIOL Week 5. Nervous System II. The Membrane Potential. Question : Is the Equilibrium Potential a set number or can it change?
Collin County Community College BIOL 2401 Week 5 Nervous System II 1 The Membrane Potential Question : Is the Equilibrium Potential a set number or can it change? Let s look at the Nernst Equation again.
More informationMEMBRANE POTENTIALS AND ACTION POTENTIALS:
University of Jordan Faculty of Medicine Department of Physiology & Biochemistry Medical students, 2017/2018 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Review: Membrane physiology
More informationΝευροφυσιολογία και Αισθήσεις
Biomedical Imaging & Applied Optics University of Cyprus Νευροφυσιολογία και Αισθήσεις Διάλεξη 5 Μοντέλο Hodgkin-Huxley (Hodgkin-Huxley Model) Response to Current Injection 2 Hodgin & Huxley Sir Alan Lloyd
More informationPETER PAZMANY CATHOLIC UNIVERSITY Consortium members SEMMELWEIS UNIVERSITY, DIALOG CAMPUS PUBLISHER
PETER PAZMANY CATHOLIC UNIVERSITY SEMMELWEIS UNIVERSITY Development of Complex Curricula for Molecular Bionics and Infobionics Programs within a consortial* framework** Consortium leader PETER PAZMANY
More information9.01 Introduction to Neuroscience Fall 2007
MIT OpenCourseWare http://ocw.mit.edu 9.01 Introduction to Neuroscience Fall 2007 For information about citing these materials or our Terms of Use, visit: http://ocw.mit.edu/terms. 9.01 Recitation (R02)
More informationNEURONS, SENSE ORGANS, AND NERVOUS SYSTEMS CHAPTER 34
NEURONS, SENSE ORGANS, AND NERVOUS SYSTEMS CHAPTER 34 KEY CONCEPTS 34.1 Nervous Systems Are Composed of Neurons and Glial Cells 34.2 Neurons Generate Electric Signals by Controlling Ion Distributions 34.3
More informationPassive Membrane Properties
Passive Membrane Properties Communicating through a leaky garden hose... Topics I Introduction & Electrochemical Gradients Passive Membrane Properties Action Potentials Voltage-Gated Ion Channels Topics
More informationThe Membrane Potential
The Membrane Potential Graphics are used with permission of: adam.com (http://www.adam.com/) Benjamin Cummings Publishing Co (http://www.aw.com/bc) ** It is suggested that you carefully label each ion
More informationControl and Integration. Nervous System Organization: Bilateral Symmetric Animals. Nervous System Organization: Radial Symmetric Animals
Control and Integration Neurophysiology Chapters 10-12 Nervous system composed of nervous tissue cells designed to conduct electrical impulses rapid communication to specific cells or groups of cells Endocrine
More informationBasic elements of neuroelectronics -- membranes -- ion channels -- wiring
Computing in carbon Basic elements of neuroelectronics -- membranes -- ion channels -- wiring Elementary neuron models -- conductance based -- modelers alternatives Wires -- signal propagation -- processing
More informationCh. 5. Membrane Potentials and Action Potentials
Ch. 5. Membrane Potentials and Action Potentials Basic Physics of Membrane Potentials Nerve and muscle cells: Excitable Capable of generating rapidly changing electrochemical impulses at their membranes
More informationQuantitative Electrophysiology
ECE 795: Quantitative Electrophysiology Notes for Lecture #4 Wednesday, October 4, 2006 7. CHEMICAL SYNAPSES AND GAP JUNCTIONS We will look at: Chemical synapses in the nervous system Gap junctions in
More informationCell membrane resistance and capacitance
Cell membrane resistance and capacitance 1 Two properties of a cell membrane gives rise to two passive electrical properties: Resistance: Leakage pathways allow inorganic ions to cross the membrane. Capacitance:
More information7 Membrane Potential. The Resting Membrane Potential Results From the Separation of Charges Across the Cell Membrane. Back.
Back 7 Membrane Potential John Koester Steven A. Siegelbaum INFORMATION IS CARRIED WITHIN and between neurons by electrical and chemical signals. Transient electrical signals are particularly important
More informationNervous Lecture Test Questions Set 2
Nervous Lecture Test Questions Set 2 1. The role of chloride in a resting membrane potential: a. creates resting potential b. indirectly causes repolarization c. stabilization of sodium d. it has none,
More informationLecture 04, 04 Sept 2003 Chapters 4 and 5. Vertebrate Physiology ECOL 437 University of Arizona Fall instr: Kevin Bonine t.a.
Lecture 04, 04 Sept 2003 Chapters 4 and 5 Vertebrate Physiology ECOL 437 University of Arizona Fall 2003 instr: Kevin Bonine t.a.: Bret Pasch Vertebrate Physiology 437 1. Membranes (CH4) 2. Nervous System
More informationChapter 2 Cellular Homeostasis and Membrane Potential
Chapter 2 Cellular Homeostasis and Membrane Potential 2.1 Membrane Structure and Composition The human cell can be considered to consist of a bag of fluid with a wall that separates the internal, or intracellular,
More informationUniversality of sensory-response systems
excite.org(anism): Electrical Signaling Universality of sensory-response systems Three step process: sensation-integration-response Bacterial chemotaxis Madigan et al. Fig. 8.24 Rick Stewart (CBMG) Human
More informationNeural Conduction. biologyaspoetry.com
Neural Conduction biologyaspoetry.com Resting Membrane Potential -70mV A cell s membrane potential is the difference in the electrical potential ( charge) between the inside and outside of the cell. The
More informationPropagation& Integration: Passive electrical properties
Fundamentals of Neuroscience (NSCS 730, Spring 2010) Instructor: Art Riegel; email: Riegel@musc.edu; Room EL 113; time: 9 11 am Office: 416C BSB (792.5444) Propagation& Integration: Passive electrical
More informationNeuroscience: Exploring the Brain
Slide 1 Neuroscience: Exploring the Brain Chapter 3: The Neuronal Membrane at Rest Slide 2 Introduction Action potential in the nervous system Action potential vs. resting potential Slide 3 Not at rest
More informationNeuroscience 201A Exam Key, October 7, 2014
Neuroscience 201A Exam Key, October 7, 2014 Question #1 7.5 pts Consider a spherical neuron with a diameter of 20 µm and a resting potential of -70 mv. If the net negativity on the inside of the cell (all
More informationSlide 1. Slide 2. Membrane Transport Mechanisms II and the Nerve Action Potential. Epithelia
Slide 1 Membrane Transport Mechanisms II and the Nerve Action Potential Slide 2 Apical Basolateral Epithelia Microvilli Tight junction Basal Lamina Lie on a sheet of connective tissue (basal lamina) Tight
More informationResting Distribution of Ions in Mammalian Neurons. Outside Inside (mm) E ion Permab. K Na Cl
Resting Distribution of Ions in Mammalian Neurons Outside Inside (mm) E ion Permab. K + 5 100-81 1.0 150 15 +62 0.04 Cl - 100 10-62 0.045 V m = -60 mv V m approaches the Equilibrium Potential of the most
More informationSUMMARY OF THE EVENTS WHICH TRIGGER AN ELECTRICAL IMPUSLE IN NERVE CELLS (see figures on the following page)
Anatomy and Physiology/AP Biology ACTION POTENTIAL SIMULATION BACKGROUND: The plasma membrane of cells is a selectively permeable barrier, which separates the internal contents of the cell from the surrounding
More informationPROPERTY OF ELSEVIER SAMPLE CONTENT - NOT FINAL. The Nervous System and Muscle
The Nervous System and Muscle SECTION 2 2-1 Nernst Potential 2-2 Resting Membrane Potential 2-3 Axonal Action Potential 2-4 Neurons 2-5 Axonal Conduction 2-6 Morphology of Synapses 2-7 Chemical Synaptic
More informationTransport of ions across plasma membranes
Transport of ions across plasma membranes Plasma Membranes of Excitable tissues Ref: Guyton, 13 th ed: pp: 61-71. 12 th ed: pp: 57-69. 11th ed: p57-71, Electrical properties of plasma membranes Part A:
More informationACTION POTENTIAL. Dr. Ayisha Qureshi Professor MBBS, MPhil
ACTION POTENTIAL Dr. Ayisha Qureshi Professor MBBS, MPhil DEFINITIONS: Stimulus: A stimulus is an external force or event which when applied to an excitable tissue produces a characteristic response. Subthreshold
More informationHousekeeping, 26 January 2009
5 th & 6 th Lectures Mon 26 & Wed 28 Jan 2009 Vertebrate Physiology ECOL 437 (MCB/VetSci 437) Univ. of Arizona, spring 2009 Neurons Chapter 11 Kevin Bonine & Kevin Oh 1. Finish Solutes + Water 2. Neurons
More informationNeurons. 5 th & 6 th Lectures Mon 26 & Wed 28 Jan Finish Solutes + Water. 2. Neurons. Chapter 11
5 th & 6 th Lectures Mon 26 & Wed 28 Jan 2009 Vertebrate Physiology ECOL 437 (MCB/VetSci 437) Univ. of Arizona, spring 2009 Neurons Chapter 11 Kevin Bonine & Kevin Oh 1. Finish Solutes + Water 2. Neurons
More informationBiomedical Instrumentation
ELEC ENG 4BD4: Biomedical Instrumentation Lecture 5 Bioelectricity 1. INTRODUCTION TO BIOELECTRICITY AND EXCITABLE CELLS Historical perspective: Bioelectricity first discovered by Luigi Galvani in 1780s
More information9 Generation of Action Potential Hodgkin-Huxley Model
9 Generation of Action Potential Hodgkin-Huxley Model (based on chapter 12, W.W. Lytton, Hodgkin-Huxley Model) 9.1 Passive and active membrane models In the previous lecture we have considered a passive
More informationChapter 37 Active Reading Guide Neurons, Synapses, and Signaling
Name: AP Biology Mr. Croft Section 1 1. What is a neuron? Chapter 37 Active Reading Guide Neurons, Synapses, and Signaling 2. Neurons can be placed into three groups, based on their location and function.
More informationAction Potentials and Synaptic Transmission Physics 171/271
Action Potentials and Synaptic Transmission Physics 171/271 Flavio Fröhlich (flavio@salk.edu) September 27, 2006 In this section, we consider two important aspects concerning the communication between
More informationBalance of Electric and Diffusion Forces
Balance of Electric and Diffusion Forces Ions flow into and out of the neuron under the forces of electricity and concentration gradients (diffusion). The net result is a electric potential difference
More informationNeuron. Detector Model. Understanding Neural Components in Detector Model. Detector vs. Computer. Detector. Neuron. output. axon
Neuron Detector Model 1 The detector model. 2 Biological properties of the neuron. 3 The computational unit. Each neuron is detecting some set of conditions (e.g., smoke detector). Representation is what
More informationThe Membrane Potential
The Membrane Potential Graphics are used with permission of: Pearson Education Inc., publishing as Benjamin Cummings (http://www.aw-bc.com) ** It is suggested that you carefully label each ion channel
More information2.6 The Membrane Potential
2.6: The Membrane Potential 51 tracellular potassium, so that the energy stored in the electrochemical gradients can be extracted. Indeed, when this is the case experimentally, ATP is synthesized from
More informationBasic elements of neuroelectronics -- membranes -- ion channels -- wiring. Elementary neuron models -- conductance based -- modelers alternatives
Computing in carbon Basic elements of neuroelectronics -- membranes -- ion channels -- wiring Elementary neuron models -- conductance based -- modelers alternatives Wiring neurons together -- synapses
More informationLecture 2. Excitability and ionic transport
Lecture 2 Excitability and ionic transport Selective membrane permeability: The lipid barrier of the cell membrane and cell membrane transport proteins Chemical compositions of extracellular and intracellular
More informationSTUDIES OF CHANGING MEMBRANE POTENTIAL * : 1. BASIC ELECTRICAL THEORY, 2. GRADED AND ACTION POTENTIALS 3. THE VOLTAGE CLAMP AND MEMBRANE POTENTIALS
STUDIES OF CHANGING MEMBRANE POTENTIAL * : 1. BASIC ELECTRICAL THEORY, 2. GRADED AND ACTION POTENTIALS 3. THE VOLTAGE CLAMP AND MEMBRANE POTENTIALS I. INTRODUCTION A. So far we have only considered the
More informationEditorial. What is the true resting potential of small cells? Jean-Marc Dubois
Gen. Physiol. Biophys. (2000), 19, 3 7 3 Editorial What is the true resting potential of small cells? Jean-Marc Dubois In order to understand almost anything, it is necessary to first obtain a measurement
More informationNervous Systems: Neuron Structure and Function
Nervous Systems: Neuron Structure and Function Integration An animal needs to function like a coherent organism, not like a loose collection of cells. Integration = refers to processes such as summation
More informationNeuron Structure. Why? Model 1 Parts of a Neuron. What are the essential structures that make up a neuron?
Why? Neuron Structure What are the essential structures that make up a neuron? Cells are specialized for different functions in multicellular organisms. In animals, one unique kind of cell helps organisms
More informationCh. 3: Cells & Their Environment
Ch. 3: Cells & Their Environment OBJECTIVES: 1. Understand cell membrane permeability 2. To recognize different types of cellular transport (passive vs active) 3. To understand membrane potential and action
More informationIon Channel Structure and Function (part 1)
Ion Channel Structure and Function (part 1) The most important properties of an ion channel Intrinsic properties of the channel (Selectivity and Mode of Gating) + Location Physiological Function Types
More informationThe Neuron - F. Fig. 45.3
excite.org(anism): Electrical Signaling The Neuron - F. Fig. 45.3 Today s lecture we ll use clickers Review today 11:30-1:00 in 2242 HJ Patterson Electrical signals Dendrites: graded post-synaptic potentials
More informationNeurons and Nervous Systems
34 Neurons and Nervous Systems Concept 34.1 Nervous Systems Consist of Neurons and Glia Nervous systems have two categories of cells: Neurons, or nerve cells, are excitable they generate and transmit electrical
More informationIntroduction and the Hodgkin-Huxley Model
1 Introduction and the Hodgkin-Huxley Model Richard Bertram Department of Mathematics and Programs in Neuroscience and Molecular Biophysics Florida State University Tallahassee, Florida 32306 Reference:
More informationBiological membranes and bioelectric phenomena
Lectures on Medical Biophysics Dept. Biophysics, Medical faculty, Masaryk University in Brno Biological membranes and bioelectric phenomena A part of this lecture was prepared on the basis of a presentation
More informationme239 mechanics of the cell - syllabus me239 mechanics of the cell me239 mechanics of the cell - grading me239 mechanics of the cell - overview
6 mechanotransduction wong, goktepe, kuhl [2010] me239 mechanics of the cell add l information http://biomechanics.stanford.edu and coursework 1 me239 mechanics of the cell - syllabus favorite topics in
More informationDecoding. How well can we learn what the stimulus is by looking at the neural responses?
Decoding How well can we learn what the stimulus is by looking at the neural responses? Two approaches: devise explicit algorithms for extracting a stimulus estimate directly quantify the relationship
More informationNeurons and the membrane potential. N500 John Beggs 23 Aug, 2016
Neurons and the membrane potential N500 John Beggs 23 Aug, 2016 My background, briefly Neurons Structural elements of a typical neuron Figure 1.2 Some nerve cell morphologies found in the human
More informationOrganization of the nervous system. Tortora & Grabowski Principles of Anatomy & Physiology; Page 388, Figure 12.2
Nervous system Organization of the nervous system Tortora & Grabowski Principles of Anatomy & Physiology; Page 388, Figure 12.2 Autonomic and somatic efferent pathways Reflex arc - a neural pathway that
More informationAction Potentials & Nervous System. Bio 219 Napa Valley College Dr. Adam Ross
Action Potentials & Nervous System Bio 219 Napa Valley College Dr. Adam Ross Review: Membrane potentials exist due to unequal distribution of charge across the membrane Concentration gradients drive ion
More informationElectrical Engineering 3BB3: Cellular Bioelectricity (2008) Solutions to Midterm Quiz #1
Electrical Engineering 3BB3: Cellular Bioelectricity (2008) Solutions to Midter Quiz #1 1. In typical excitable cells there will be a net influx of K + through potassiu ion channels if: a. V Vrest >, b.
More informationWhat are neurons for?
5 th & 6 th Lectures Mon 26 & Wed 28 Jan 2009 Vertebrate Physiology ECOL 437 (MCB/VetSci 437) Univ. of Arizona, spring 2009 Kevin Bonine & Kevin Oh 1. Finish Solutes Water 2. Neurons Neurons Chapter 11
More informationCOGNITIVE SCIENCE 107A
COGNITIVE SCIENCE 107A Electrophysiology: Electrotonic Properties 2 Jaime A. Pineda, Ph.D. The Model Neuron Lab Your PC/CSB115 http://cogsci.ucsd.edu/~pineda/cogs107a/index.html Labs - Electrophysiology
More informationMembrane Physiology. Dr. Hiwa Shafiq Oct-18 1
Membrane Physiology Dr. Hiwa Shafiq 22-10-2018 29-Oct-18 1 Chemical compositions of extracellular and intracellular fluids. 29-Oct-18 2 Transport through the cell membrane occurs by one of two basic processes:
More informationCELL BIOLOGY - CLUTCH CH. 9 - TRANSPORT ACROSS MEMBRANES.
!! www.clutchprep.com K + K + K + K + CELL BIOLOGY - CLUTCH CONCEPT: PRINCIPLES OF TRANSMEMBRANE TRANSPORT Membranes and Gradients Cells must be able to communicate across their membrane barriers to materials
More informationProperties of the living organism. Interaction between living organism and the environment. Processing informations. Definitions
thermodynamics material energy Interaction between living organism and the environment Open system: free material and energy exchange. Processing informations information processing answer Properties of
More information