PSIO 603/BME Dr. Janis Burt February 19, 2007 MRB 422; jburt@u.arizona.edu. MUSCLE EXCITABILITY - Ventricle

Size: px
Start display at page:

Download "PSIO 603/BME 511 1 Dr. Janis Burt February 19, 2007 MRB 422; 626-6833 jburt@u.arizona.edu. MUSCLE EXCITABILITY - Ventricle"

Transcription

1 SIO 63/BME Dr. Janis Burt February 19, 27 MRB 422; MUSCLE EXCITABILITY - Ventricle READING: Boron & Boulpaep pages: OBJECTIVES: 1. Draw a picture of the heart in vertical (frontal plane) section. Include the elements of the conduction system in your drawing. 2. Describe the sequence of activation of the heart. List the three benefits of the sequence in optimizing cardiac function. 3. Draw an action potential characteristic of ventricular cells, label its phases, describe the membrane's relative ion permeabilities for each phase, and compare these relative permeabilities to those of skeletal muscle and nerve. 4. Discuss the significance for cardiac function of the high resting potassium permeability. 5. Relative to an action potential, illustrate the timing of the three refractory periods observed in a cardiac myocyte. rovide a definition for each refractory period. State which channel s activation/inactivation characteristics determine the refractory state of the heart. Graph the relationship between that channel s availability and membrane potential. State the significance of refractory periods to normal pulsatile function of the heart. LECTURE OUTLINE I. Sequence of Activation Overview (Objectives 1, 2) A. Normal Sequence of Activation: Sinoatrial node right atrium, interatrial tracts, and internodal tracts atrioventricular node and left atria atrioventricular node Bundle of HIS bundle branches urkinje fibers ventricle (apex to base, endocardial surface to epicardial surface) B. Benefits of normal activation sequence 1. Maximizes ventricular filling 2. Optimizes ventricular contraction by stabilizing valve leaflets and septum early in contraction 3. Maximizes ejection by synchronizing contractile activation in the ventricular wall II. Excitability of Ventricular Cells: A. The Action potential - Figure 1&2 (Objectives 3 & 4) 1. Action potential duration is 1x longer than in SKM or nerve with 4 distinct phases. 2. During hase 4 the membrane potential is dominated by K (I K1 channels), which are ~1x more numerous than in SKM or nerve. a) High resting K : stabilizes the resting membrane potential; minimizes arrhythmias by necessitating a large stimulus (depolarization of neighboring cells) to result in successful activation (ventricles are slaves to the pacemaker cells). b) The resting permeabilities for K : Na : Cl are: 1 :.5 :.1 (note: Na is 1-5x higher than in nerve or SKM; Cl is comparable to nerve, 1x less than SKM. c) The density of Na,K-ATase enzymes in heart membrane is greater than SKM or nerve. 3. During phase, the action potential upstroke, Na increases resulting in an influx of Na + (Na-channel comparable to nerve and SKM but with slower kinetics). 4. hase 1, the early repolarization phase, involves a transient increase in K (resulting in efflux of K + ) and Na-channel inactivation.

2 SIO 63/BME Dr. Janis Burt February 19, 27 MRB 422; hase 2, the plateau phase, requires an increase in Ca and a decrease in K (decrease in I K1 activity). a) The calcium channel is voltage activated, dihydropyridine sensitive, and regulated by cam-dependent protein kinase. b) K decreases as Mg 2+ blocks the I K1 channels. 6. hase 3, repolarization, voltage activated K channels open (I K - delayed rectifiers) and Ca channels close. As the membrane repolarizes Mg 2+ block of I K1 channels is relieved and resting membrane permeabilities are restored. 7. As heart rate increases action potential duration decreases; however time between action potentials shortens to a greater extent than the action potential. B. Refractory periods Figures 1,3,4 (Objective 5) 1. absolute refractory period - the period of time during which no action potential can be initiated, regardless of stimulus strength (AR in Figure 1) and is considerably longer in duration than observed in skeletal muscle. 2. effective refractory period, the period of time during which no propagated action potentials can be elicited regardless of stimulus strength. 3. relative refractory period (RR) the period of time in which a response can be elicited but the stimulus required is larger than normal and the amplitude of the action potential is abnormally small. 4. supranormal period (SN) the period during which a slightly smaller than normal stimulus elicits a propagated response, although the amplitude of the action potential is reduced compared to normal. 5. Full recovery time (FRT) represents the time before a normal action potential can be elicited with a normal stimulus. 6. Refractory properties reflect the recovery of Na-channels to a state from which they can be activated. 7. The long duration of the action potential and the refractory characteristics of the cell insure that cardiac cells are nearly completely relaxed by the time they are repolarized. Cardiac muscle cannot be tetanized because of these membrane properties. LECTURE NOTES I. Sequence of Activation (Objectives 1 & 2) The normally functioning heart follows a specific pattern of activation every time it contracts. This pattern optimizes function by maximizing ventricular filling, contraction and ejection. The activation sequence begins with an action potential at the sinoatrial node, the pacemaker of the heart. The electrical event spreads via gap junctions to the surrounding atria and along specialized interatrial and internodal conduction pathways to the left atrium and atrioventricular node (AV node), respectively. The AV node represents the only point of electrical continuity between the atrium and ventricle. When the excitatory event leaves the AV node, it passes rapidly along the Bundle of HIS, the bundle branches and the purkinje network to the ventricles. Activation of the ventricles occurs initially at the septum and apex of the heart and progresses towards the base of the heart, and from the endocardial surfaces towards the epicardial surfaces. Activation of the ventricles begins ~.15 sec after the atria. This delay between atrial and ventricular activation assures maximal ventricular filling. The sequence of activation within the ventricle insures efficient contraction and ejection by: i) stabilizing the septum and valve leaflets early in the contraction, and ii) activating from apex-to-base and endocardium-to-epicardium. The latter results in pushing the blood towards the aortic valve and

3 SIO 63/BME Dr. Janis Burt February 19, 27 MRB 422; prevents cells located at the epicardial surface from having to contract against "flacid" cells near the endocardial surface. How do the electrical properties of the cells of the heart insure that this sequence occurs beat after beat? When this pathway of normal activation fails, what properties insure a back-up strategy for activation of the heart? What circumstances predispose the heart to arrhythmias? These are the questions we will address over the next week or two. II. Excitability in Ventricular, Atrial and Non-nodal Conducting Cells (Objectives 3 & 4) A. The Action potential: The action potentials of ventricular and non-nodal conduction system cells last for ~25-3 msec; atrial cell action potentials last ~15 msec. These long duration potentials are characterized by several phases (-4) as shown in Figure 1. hase 4 -- diastole or rest. The resting permeability of the ventricular cell membrane is dominated by potassium. Ventricular cells have an approximate ten fold higher resting permeability to potassium than do skeletal muscle or nerve cells. This high resting potassium permeability (like the high chloride permeability in skeletal muscle) stabilizes the resting membrane potential reducing the risk of arrhythmias by necessitating a large stimulus to excite the cells. The ventricles are thereby rendered slaves to the pacemaker cells of the heart. The permeabilities of Na and Cl (relative to potassium) are ( K : Cl : Na ) 1 :.1 :.5. Note that the ventricular cell is more permeable to Na + at rest than other excitable cells. As a consequence of the high Na + permeability, the density of Na,K-ATase enzymes in the membrane is high. Since this pump is electrogenic, its activity contributes several millivolts to the resting membrane potential. hase -- action potential upstroke. As in skeletal muscle and nerve the upstroke results from an increase in Na. The voltage gated Na channel expressed in the heart is a different gene product than that expressed by skeletal muscle or neural tissues. hase 1 -- early repolarization. The ionic basis of this phase is a transient increase in potassium permeability (I K-to ) and Na-channel inactivation. hase 2 -- plateau. This is the most distinctive feature of the cardiac action potential. The plateau requires two changes in membrane permeability: 1) an increase in calcium permeability through voltage-activated, L-type Ca channels that are dihydrophyridine sensitive; and 2) a decrease in potassium permeability. During the plateau phase potassium permeability is ~ 1/1 the resting potassium permeability. This decrease in K is indirectly voltage dependent at depolarized potentials Mg 2+ enters and blocks the I K1 channels. hase 3 -- repolarization. Repolarization occurs as Ca 2+ channels inactivate and voltage activated K channels open (delayed rectifiers - I K ). As repolarization proceeds the I K channels deactivate and the Mg 2+ block of the I K1 channels is relieved, which restores the resting permeabilities of the membrane. Figure 1 Action potential and underlying permeability changes for ventricular and purkinje cells. (modified from reference 2) 1 1 * 2 3 4

4 SIO 63/BME Dr. Janis Burt February 19, 27 MRB 422; It is interesting to note that the permeability of most excitable cells is lowest when the membrane potential is at the resting level. This conserves energy by reducing the number of Na + and K + ions that need to be pumped. Cardiac tissue is the exception to the rule. The cardiac cell s overall membrane permeability is actually less during the active phase (dominated by the plateau) than during the rest phase. In large part, this difference reflects high resting permeability to K + and the block of the underlying potassium channels (I K1 ) that occurs with depolarization. Lower permeability during activation is advantageous to the heart during high heart rates because K + efflux is spared and the energy required to restore that K + to the intracellular space (via the Na,K-ATase) conserved for contraction. Figure 2 - Epinephrine (black vs. grey curves) shortens the ventricular action potential by enhancing I Ca-L and I K. (modified from reference 2) Sympathetic and arasympathetic Control The ventricles are well innervated by sympathetic fibers that release norepinephrine. This transmitter binds to β-adrenergic receptors, which transduce the activation of protein kinase A. This kinase enhances the activity of I Ca-L and I K channels (see figure 2). In addition to delivering more calcium to the contractile apparatus (stronger contractions), these changes in channel activity cause a shortening of the action potential s duration. B. Refractory eriods (Objective 5) Due to the activation/inactivation characteristics of the voltage-gated Na + channel underlying phase, cardiac muscle is refractory to stimulation until it is repolarized. At the cellular level, the period of time during which no action potential can be initiated, regardless of stimulus strength, is called the absolute refractory period (AR - Figure 1). At the tissue level, the absolute refractory period translates into the effective refractory period, which is defined as the period of time during which no propagated action potentials can be elicited. The AR lasts until the membrane potential repolarizes to levels more negative than -65 mv. The AR is followed by a period in which an action potential can be elicited but the stimulus required is larger than normal and the amplitude of the elicited action potential is abnormally small. This period is the relative refractory period (RR). As the membrane potential repolarizes an increasing fraction of the total Na + channels becomes available for activation (Figure 3). Thus, a stimulus delivered at the beginning of the RR will elicit an action potential of small amplitude, and one delivered towards the end of the RR will elicit an action potential of larger amplitude. The RR is followed by the supranormal period (SN) during which a slightly smaller than normal stimulus elicits a normal propagated response. Full recovery time (FRT) represents the time after which a normal action potential can be elicited with a normal stimulus. 1 Figure 3 - Na-channel availability determines the refractory properties of the heart. (modified from reference 2) Repolarize % Na Channels Available FRT SN RR AR otential (mv)

5 SIO 63/BME Dr. Janis Burt February 19, 27 MRB 422; The refractory properties of the cardiac cell are suited to the function of the organ. The timing of the electrical and contractile events is such that the heart relaxes before it can contract again (Figure 4). At a heart rate of 72 beats/min (bpm) and action potential duration of ~3 msec, the time between beats (referred to as electrical diastole) is around 53 msec. At a heart rate of 2 bpm and an action potential duration of 3 msec the interval between beats would be msec. Since it is during diastole that the heart has time to fill with blood, it is clear that in order to be an effective pump at fast heart rates the duration of the action potential must decrease. In general, the duration of the action potential varies inversely with the frequency. Shortening of the action potential reflects the effects of sympathetic drive on Ca and K channel function. C. Action otential Duration Action potential duration, even within the ventricle, varies. The purkinje fibers have the longest duration (~3 or longer msec at resting heart rates), atrial cells the shortest (15-2msec at resting heart rates); within the ventricle cells closest to the chamber have longer duration action potentials than the those at the epicardial surface. Figure 4 - Cardiac contraction is nearly complete with the onset of phase 4 (top panel). Consequently, tetanus is not possible in this muscle type. In skeletal muscle, repolarization occurs early in contraction, making summation and tetanus possible. otential (mv) otential This latter comparison is worth remembering the ramifications of this are that despite depolarizing after ventricular cells near the endocardium, the epicardial cells repolarize first. How can so many different durations result from the same types of channels? Although all these cells have the same array of channel types, their relative numbers differ considerably. You might expect that delayed rectifiers would be more numerous in cells with shorter duration action potentials, if so, you would be correct. You might also expect that Ca-channel density is lower in regions with short action potentials, this too is true msec References Cited in Figures: 1. hysiology by L.S. Costanzo. W.B. Saunders Co., hiladelphia, hysiology of the Heart (2nd ed.) by A.M. Katz, Raven ress, N.Y Ionic Channels of Excitable s by Bertil Hille. (mv) 2 Tension 3 4 Tension

Lecture Outline. Cardiovascular Physiology. Cardiovascular System Function. Functional Anatomy of the Heart

Lecture Outline. Cardiovascular Physiology. Cardiovascular System Function. Functional Anatomy of the Heart Lecture Outline Cardiovascular Physiology Cardiac Output Controls & Blood Pressure Cardiovascular System Function Functional components of the cardiovascular system: Heart Blood Vessels Blood General functions

More information

Chapter 20: The Cardiovascular System: The Heart

Chapter 20: The Cardiovascular System: The Heart Chapter 20: The Cardiovascular System: The Heart Chapter Objectives ANATOMY OF THE HEART 1. Describe the location and orientation of the heart within the thorax and mediastinal cavity. 2. Describe the

More information

EXCITABILITY & ACTION POTENTIALS page 1

EXCITABILITY & ACTION POTENTIALS page 1 page 1 INTRODUCTION A. Excitable Tissue: able to generate Action Potentials (APs) (e.g. neurons, muscle cells) B. Neurons (nerve cells) a. components 1) soma (cell body): metabolic center (vital, always

More information

Introduction to Cardiac Electrophysiology, the Electrocardiogram, and Cardiac Arrhythmias INTRODUCTION

Introduction to Cardiac Electrophysiology, the Electrocardiogram, and Cardiac Arrhythmias INTRODUCTION Introduction to Cardiac Electrophysiology, the Electrocardiogram, and Cardiac Arrhythmias Alfred E. Buxton, M.D., Kristin E. Ellison, M.D., Malcolm M. Kirk, M.D., Gregory F. Michaud, M.D. INTRODUCTION

More information

Nerves and Nerve Impulse

Nerves and Nerve Impulse Nerves and Nerve Impulse Terms Absolute refractory period: Period following stimulation during which no additional action potential can be evoked. Acetylcholine: Chemical transmitter substance released

More information

Electrodes placed on the body s surface can detect electrical activity, APPLIED ANATOMY AND PHYSIOLOGY. Circulatory system

Electrodes placed on the body s surface can detect electrical activity, APPLIED ANATOMY AND PHYSIOLOGY. Circulatory system 4 READING AND INTERPRETING THE ELECTROCARDIOGRAM Electrodes placed on the body s surface can detect electrical activity, which occurs in the heart. The recording of these electrical events comprises an

More information

Electrocardiography I Laboratory

Electrocardiography I Laboratory Introduction The body relies on the heart to circulate blood throughout the body. The heart is responsible for pumping oxygenated blood from the lungs out to the body through the arteries and also circulating

More information

MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question.

MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question. Exam Name MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question. 1) What term is used to refer to the process of electrical discharge and the flow of electrical

More information

Cardiovascular System

Cardiovascular System Topics to Review Diffusion Skeletal muscle fiber (cell) anatomy Membrane potential and action potentials Action potential propagation Excitation-contraction coupling in skeletal muscle skeletal muscle

More information

Resting membrane potential ~ -70mV - Membrane is polarized

Resting membrane potential ~ -70mV - Membrane is polarized Resting membrane potential ~ -70mV - Membrane is polarized (ie) Electrical charge on the outside of the membrane is positive while the electrical charge on the inside of the membrane is negative Changes

More information

Activity 5: The Action Potential: Measuring Its Absolute and Relative Refractory Periods. 250 20 Yes. 125 20 Yes. 60 20 No. 60 25 No.

Activity 5: The Action Potential: Measuring Its Absolute and Relative Refractory Periods. 250 20 Yes. 125 20 Yes. 60 20 No. 60 25 No. 3: Neurophysiology of Nerve Impulses (Part 2) Activity 5: The Action Potential: Measuring Its Absolute and Relative Refractory Periods Interval between stimuli Stimulus voltage (mv) Second action potential?

More information

The Action Potential Graphics are used with permission of: adam.com (http://www.adam.com/) Benjamin Cummings Publishing Co (http://www.awl.

The Action Potential Graphics are used with permission of: adam.com (http://www.adam.com/) Benjamin Cummings Publishing Co (http://www.awl. The Action Potential Graphics are used with permission of: adam.com (http://www.adam.com/) Benjamin Cummings Publishing Co (http://www.awl.com/bc) ** If this is not printed in color, it is suggested you

More information

Introduction to Electrocardiography. The Genesis and Conduction of Cardiac Rhythm

Introduction to Electrocardiography. The Genesis and Conduction of Cardiac Rhythm Introduction to Electrocardiography Munther K. Homoud, M.D. Tufts-New England Medical Center Spring 2008 The Genesis and Conduction of Cardiac Rhythm Automaticity is the cardiac cell s ability to spontaneously

More information

CHAPTER XV PDL 101 HUMAN ANATOMY & PHYSIOLOGY. Ms. K. GOWRI. M.Pharm., Lecturer.

CHAPTER XV PDL 101 HUMAN ANATOMY & PHYSIOLOGY. Ms. K. GOWRI. M.Pharm., Lecturer. CHAPTER XV PDL 101 HUMAN ANATOMY & PHYSIOLOGY Ms. K. GOWRI. M.Pharm., Lecturer. Types of Muscle Tissue Classified by location, appearance, and by the type of nervous system control or innervation. Skeletal

More information

Note: The left and right sides of the heart must pump exactly the same volume of blood when averaged over a period of time

Note: The left and right sides of the heart must pump exactly the same volume of blood when averaged over a period of time page 1 HEART AS A PUMP A. Functional Anatomy of the Heart 1. Two pumps, arranged in series a. right heart: receives blood from the systemic circulation (via the great veins and vena cava) and pumps blood

More information

THE HEART Dr. Ali Ebneshahidi

THE HEART Dr. Ali Ebneshahidi THE HEART Dr. Ali Ebneshahidi Functions is of the heart & blood vessels 1. The heart is an essential pumping organ in the cardiovascular system where the right heart pumps deoxygenated blood (returned

More information

Electrophysiology Introduction, Basics. The Myocardial Cell. Chapter 1- Thaler

Electrophysiology Introduction, Basics. The Myocardial Cell. Chapter 1- Thaler Electrophysiology Introduction, Basics Chapter 1- Thaler The Myocardial Cell Syncytium Resting state Polarized negative Membrane pump Depolarization fundamental electrical event of the heart Repolarization

More information

Exchange solutes and water with cells of the body

Exchange solutes and water with cells of the body Chapter 8 Heart and Blood Vessels Three Types of Blood Vessels Transport Blood Arteries Carry blood away from the heart Transport blood under high pressure Capillaries Exchange solutes and water with cells

More information

Action Potentials I Generation. Reading: BCP Chapter 4

Action Potentials I Generation. Reading: BCP Chapter 4 Action Potentials I Generation Reading: BCP Chapter 4 Action Potentials Action potentials (AP s) aka Spikes (because of how they look in an electrical recording of Vm over time). Discharges (descriptive

More information

REVIEW SHEET EXERCISE 3 Neurophysiology of Nerve Impulses Name Lab Time/Date. The Resting Membrane Potential

REVIEW SHEET EXERCISE 3 Neurophysiology of Nerve Impulses Name Lab Time/Date. The Resting Membrane Potential REVIEW SHEET EXERCISE 3 Neurophysiology of Nerve Impulses Name Lab Time/Date ACTIVITY 1 The Resting Membrane Potential 1. Explain why increasing extracellular K + reduces the net diffusion of K + out of

More information

ACLS Chapter 3 Rhythm Review Instructor Lesson Plan to Accompany ACLS Study Guide 3e

ACLS Chapter 3 Rhythm Review Instructor Lesson Plan to Accompany ACLS Study Guide 3e ACLS Chapter 3 Rhythm Review Lesson Plan Required reading before this lesson: ACLS Study Guide 3e Textbook Chapter 3 Materials needed: Multimedia projector, computer, ACLS Chapter 3 Recommended minimum

More information

Electrocardiogram and Heart Sounds

Electrocardiogram and Heart Sounds Electrocardiogram and Heart Sounds An introduction to the recording and analysis of electrocardiograms, and the sounds of the heart. Written by Staff of ADInstruments Introduction The beating of the heart

More information

Bi 360: Midterm Review

Bi 360: Midterm Review Bi 360: Midterm Review Basic Neurobiology 1) Many axons are surrounded by a fatty insulating sheath called myelin, which is interrupted at regular intervals at the Nodes of Ranvier, where the action potential

More information

INTRODUCTORY GUIDE TO IDENTIFYING ECG IRREGULARITIES

INTRODUCTORY GUIDE TO IDENTIFYING ECG IRREGULARITIES INTRODUCTORY GUIDE TO IDENTIFYING ECG IRREGULARITIES NOTICE: This is an introductory guide for a user to understand basic ECG tracings and parameters. The guide will allow user to identify some of the

More information

QRS Complexes. Fast & Easy ECGs A Self-Paced Learning Program

QRS Complexes. Fast & Easy ECGs A Self-Paced Learning Program 6 QRS Complexes Fast & Easy ECGs A Self-Paced Learning Program Q I A ECG Waveforms Normally the heart beats in a regular, rhythmic fashion producing a P wave, QRS complex and T wave I Step 4 of ECG Analysis

More information

Starling s Law Regulation of Myocardial Performance Intrinsic Regulation of Myocardial Performance

Starling s Law Regulation of Myocardial Performance Intrinsic Regulation of Myocardial Performance Regulation of Myocardial Performance Intrinsic Regulation of Myocardial Performance Just as the heart can initiate its own beat in the absence of any nervous or hormonal control, so also can the myocardium

More information

Anatomi & Fysiologi 060301. The cardiovascular system (chapter 20) The circulation system transports; What the heart can do;

Anatomi & Fysiologi 060301. The cardiovascular system (chapter 20) The circulation system transports; What the heart can do; The cardiovascular system consists of; The cardiovascular system (chapter 20) Principles of Anatomy & Physiology 2009 Blood 2 separate pumps (heart) Many blood vessels with varying diameter and elasticity

More information

Heart and Vascular System Practice Questions

Heart and Vascular System Practice Questions Heart and Vascular System Practice Questions Student: 1. The pulmonary veins are unusual as veins because they are transporting. A. oxygenated blood B. de-oxygenated blood C. high fat blood D. nutrient-rich

More information

12. Nervous System: Nervous Tissue

12. Nervous System: Nervous Tissue 12. Nervous System: Nervous Tissue I. Introduction to the Nervous System General functions of the nervous system The nervous system has three basic functions: 1. Gather sensory input from the environment

More information

CHAPTER 5 SIGNALLING IN NEURONS

CHAPTER 5 SIGNALLING IN NEURONS 5.1. SYNAPTIC TRANSMISSION CHAPTER 5 SIGNALLING IN NEURONS One of the main functions of neurons is to communicate with other neurons. An individual neuron may receive information from many different sources.

More information

By the end of this continuing education module the clinician will be able to:

By the end of this continuing education module the clinician will be able to: EKG Interpretation WWW.RN.ORG Reviewed March, 2015, Expires April, 2017 Provider Information and Specifics available on our Website Unauthorized Distribution Prohibited 2015 RN.ORG, S.A., RN.ORG, LLC Developed

More information

Cardiac Muscle. Learning Objectives.

Cardiac Muscle. Learning Objectives. Cardiac Muscle. Learning Objectives. At the end of this course, you should be able to : 1. describe the structure of cardiac muscle 2. understand the concept of the functional syncytium 3. give a basic

More information

PART I: Neurons and the Nerve Impulse

PART I: Neurons and the Nerve Impulse PART I: Neurons and the Nerve Impulse Identify each of the labeled structures of the neuron below. A. B. C. D. E. F. G. Identify each of the labeled structures of the neuron below. A. dendrites B. nucleus

More information

For more information about the use of the Propaq monitor, refer to the Propaq Directions For Use.

For more information about the use of the Propaq monitor, refer to the Propaq Directions For Use. Clinical Support 8500 S.W. Creekside Pl. Beaverton, OR 97008-7107 U.S.A. Telephone: 503-526-4200 Toll Free: 800-289-2500 clinicalsupport@protocol.com ELECTROCARDIOGRAPHY Introduction This article provides

More information

Lab 1: Simulation of Resting Membrane Potential and Action Potential

Lab 1: Simulation of Resting Membrane Potential and Action Potential Lab 1: Simulation of Resting Membrane Potential and Action Potential Overview The aim of the present laboratory exercise is to simulate how changes in the ion concentration or ionic conductance can change

More information

Activity 4.2.3: EKG. Introduction. Equipment. Procedure

Activity 4.2.3: EKG. Introduction. Equipment. Procedure Activity 4.2.3: EKG The following is used with permission of Vernier Software and Technology. This activity is based on the experiment Analyzing the Heart with EKG from the book Human Physiology with Vernier,

More information

Functions of Blood System. Blood Cells

Functions of Blood System. Blood Cells Functions of Blood System Transport: to and from tissue cells Nutrients to cells: amino acids, glucose, vitamins, minerals, lipids (as lipoproteins). Oxygen: by red blood corpuscles (oxyhaemoglobin - 4

More information

FUNCTIONS OF THE NERVOUS SYSTEM 1. Sensory input. Sensory receptors detects external and internal stimuli.

FUNCTIONS OF THE NERVOUS SYSTEM 1. Sensory input. Sensory receptors detects external and internal stimuli. FUNCTIONS OF THE NERVOUS SYSTEM 1. Sensory input. Sensory receptors detects external and internal stimuli. 2. Integration. The brain and spinal cord process sensory input and produce responses. 3. Homeostasis.

More information

Chapter 7: The Nervous System

Chapter 7: The Nervous System Chapter 7: The Nervous System Objectives Discuss the general organization of the nervous system Describe the structure & function of a nerve Draw and label the pathways involved in a withdraw reflex Define

More information

Evaluation copy. Analyzing the Heart with EKG. Computer

Evaluation copy. Analyzing the Heart with EKG. Computer Analyzing the Heart with EKG Computer An electrocardiogram (ECG or EKG) is a graphical recording of the electrical events occurring within the heart. In a healthy heart there is a natural pacemaker in

More information

The heart then repolarises (or refills) in time for the next stimulus and contraction.

The heart then repolarises (or refills) in time for the next stimulus and contraction. Atrial Fibrillation BRIEFLY, HOW DOES THE HEART PUMP? The heart has four chambers. The upper chambers are called atria. One chamber is called an atrium, and the lower chambers are called ventricles. In

More information

Distance Learning Program Anatomy of the Human Heart/Pig Heart Dissection Middle School/ High School

Distance Learning Program Anatomy of the Human Heart/Pig Heart Dissection Middle School/ High School Distance Learning Program Anatomy of the Human Heart/Pig Heart Dissection Middle School/ High School This guide is for middle and high school students participating in AIMS Anatomy of the Human Heart and

More information

Human Anatomy & Physiology II with Dr. Hubley

Human Anatomy & Physiology II with Dr. Hubley Human Anatomy & Physiology II with Dr. Hubley Exam #1 Name: Instructions This exam consists of 40 multiple-choice questions. Each multiple-choice question answered correctly is worth one point, and the

More information

Neurophysiology. 2.1 Equilibrium Potential

Neurophysiology. 2.1 Equilibrium Potential 2 Neurophysiology 2.1 Equilibrium Potential An understanding of the concepts of electrical and chemical forces that act on ions, electrochemical equilibrium, and equilibrium potential is a powerful tool

More information

Biology 347 General Physiology Lab Advanced Cardiac Functions ECG Leads and Einthoven s Triangle

Biology 347 General Physiology Lab Advanced Cardiac Functions ECG Leads and Einthoven s Triangle Biology 347 General Physiology Lab Advanced Cardiac Functions ECG Leads and Einthoven s Triangle Objectives Students will record a six-lead ECG from a resting subject and determine the QRS axis of the

More information

Cardiovascular Physiology

Cardiovascular Physiology Cardiovascular Physiology Heart Physiology for the heart to work properly contraction and relaxation of chambers must be coordinated cardiac muscle tissue differs from smooth and skeletal muscle tissues

More information

AP Biology I. Nervous System Notes

AP Biology I. Nervous System Notes AP Biology I. Nervous System Notes 1. General information: passage of information occurs in two ways: Nerves - process and send information fast (eg. stepping on a tack) Hormones - process and send information

More information

Biology/ANNB 261 Exam 1 Spring, 2006

Biology/ANNB 261 Exam 1 Spring, 2006 Biology/ANNB 261 Exam 1 Spring, 2006 Name * = correct answer Multiple Choice: 1. Axons and dendrites are two types of a) Neurites * b) Organelles c) Synapses d) Receptors e) Golgi cell components 2. The

More information

VCA Veterinary Specialty Center of Seattle

VCA Veterinary Specialty Center of Seattle An electrocardiogram (ECG) is a graph of the heart`s electrical current, which allows evaluation of heart rate, rhythm and conduction. Identification of conduction problems within the heart begins with

More information

Interpreting AV (Heart) Blocks: Breaking Down the Mystery

Interpreting AV (Heart) Blocks: Breaking Down the Mystery Interpreting AV (Heart) Blocks: Breaking Down the Mystery 2 Contact Hours Copyright 2012 by RN.com. All Rights Reserved. Reproduction and distribution of these materials is prohibited without the express

More information

Smooth Muscle. Smooth Muscle Structure

Smooth Muscle. Smooth Muscle Structure Smooth Muscle Spindle-shaped Small (2-5 um wide, 50-300 um long) 1 centrally placed nucleus per cell Usually organized in small to moderate sized clusters of cells Lack sarcomeres No T-tubules or terminal

More information

Cellular Calcium Dynamics. Jussi Koivumäki, Glenn Lines & Joakim Sundnes

Cellular Calcium Dynamics. Jussi Koivumäki, Glenn Lines & Joakim Sundnes Cellular Calcium Dynamics Jussi Koivumäki, Glenn Lines & Joakim Sundnes Cellular calcium dynamics A real cardiomyocyte is obviously not an empty cylinder, where Ca 2+ just diffuses freely......instead

More information

Equine Cardiovascular Disease

Equine Cardiovascular Disease Equine Cardiovascular Disease 3 rd most common cause of poor performance in athletic horses (after musculoskeletal and respiratory) Cardiac abnormalities are rare Clinical Signs: Poor performance/exercise

More information

Electrolyte Physiology. Something in the way she moves

Electrolyte Physiology. Something in the way she moves Electrolyte Physiology Something in the way she moves me Electrolyte Movement CONCENTRATION GRADIENT ELECTRICAL GRADIENT DRIVING FORCE NERNST NUMBER (E-ion) CONDUCTANCE (G-ion) PERMEABILITY CHANNELS: small

More information

HEART HEALTH WEEK 3 SUPPLEMENT. A Beginner s Guide to Cardiovascular Disease HEART FAILURE. Relatively mild, symptoms with intense exercise

HEART HEALTH WEEK 3 SUPPLEMENT. A Beginner s Guide to Cardiovascular Disease HEART FAILURE. Relatively mild, symptoms with intense exercise WEEK 3 SUPPLEMENT HEART HEALTH A Beginner s Guide to Cardiovascular Disease HEART FAILURE Heart failure can be defined as the failing (insufficiency) of the heart as a mechanical pump due to either acute

More information

NEONATAL & PEDIATRIC ECG BASICS RHYTHM INTERPRETATION

NEONATAL & PEDIATRIC ECG BASICS RHYTHM INTERPRETATION NEONATAL & PEDIATRIC ECG BASICS & RHYTHM INTERPRETATION VIKAS KOHLI MD FAAP FACC SENIOR CONSULATANT PEDIATRIC CARDIOLOGY APOLLO HOSPITAL MOB: 9891362233 ECG FAX LINE: 011-26941746 THE BASICS: GRAPH PAPER

More information

U N IT 10 NE RVOUS SYS TE M REVIEW 1. Which of the following is controlled by the somatic nervous system? A. rate of heartbeat B.

U N IT 10 NE RVOUS SYS TE M REVIEW 1. Which of the following is controlled by the somatic nervous system? A. rate of heartbeat B. U N IT 10 NE RVOUS SYS TE M REVIEW 1. Which of the following is controlled by the somatic nervous system? A. rate of heartbeat B. contraction of skeletal muscles C. increased blood flow to muscle tissue

More information

Pacers use a 5-letter code: first 3 letters most important

Pacers use a 5-letter code: first 3 letters most important PACEMAKERS 2 Pacemakers: Nomenclature Pacers use a 5-letter code: first 3 letters most important t First Letter: Chamber Paced A= Atrium V= Ventricle D= Dual (A+V) 2nd Letter: Chamber Sensed A= Atrium

More information

Vascular System The heart can be thought of 2 separate pumps from the right ventricle, blood is pumped at a low pressure to the lungs and then back

Vascular System The heart can be thought of 2 separate pumps from the right ventricle, blood is pumped at a low pressure to the lungs and then back Vascular System The heart can be thought of 2 separate pumps from the right ventricle, blood is pumped at a low pressure to the lungs and then back to the left atria from the left ventricle, blood is pumped

More information

Electrocardiography Review and the Normal EKG Response to Exercise

Electrocardiography Review and the Normal EKG Response to Exercise Electrocardiography Review and the Normal EKG Response to Exercise Cardiac Anatomy Electrical Pathways in the Heart Which valves are the a-v valves? Closure of the a-v valves is associated with which heart

More information

The action potential and nervous conduction CH Fry and RI Jabr Postgraduate Medical School, Division of Clinical Medicine, University of Surrey, UK

The action potential and nervous conduction CH Fry and RI Jabr Postgraduate Medical School, Division of Clinical Medicine, University of Surrey, UK The action potential and nervous conduction CH Fry and RI Jabr Postgraduate Medical School, Division of Clinical Medicine, University of Surrey, UK CH Fry, PhD, DSc Professor of Physiology, Division of

More information

Welcome to Vibrationdata

Welcome to Vibrationdata Welcome to Vibrationdata Acoustics Shock Vibration Signal Processing December 2004 Newsletter Ni hao Feature Articles One of my goals is to measure a wide variety of oscillating signals. In some sense,

More information

Name: Teacher: Olsen Hour:

Name: Teacher: Olsen Hour: Name: Teacher: Olsen Hour: The Nervous System: Part 1 Textbook p216-225 41 In all exercises, quizzes and tests in this class, always answer in your own words. That is the only way that you can show that

More information

Cardiology. Anatomy and Physiology of the Heart.

Cardiology. Anatomy and Physiology of the Heart. Cardiology Self Learning Package Module 1: Anatomy and Physiology of the Heart. Module 1: Anatomy and Physiology of the Heart Page 1 CONTENT Introduction Page 3 How to use the ECG Self Learning package.page

More information

Normal & Abnormal Intracardiac. Lancashire & South Cumbria Cardiac Network

Normal & Abnormal Intracardiac. Lancashire & South Cumbria Cardiac Network Normal & Abnormal Intracardiac Pressures Lancashire & South Cumbria Cardiac Network Principle Pressures recorded from catheter tip Electrical transducer - wheatstone bridge mechanical to electrical waveform

More information

Biology Slide 1 of 38

Biology Slide 1 of 38 Biology 1 of 38 2 of 38 35-2 The Nervous System What are the functions of the nervous system? 3 of 38 35-2 The Nervous System 1. Nervous system: a. controls and coordinates functions throughout the body

More information

The Action Potential

The Action Potential OpenStax-CNX module: m46526 1 The Action Potential OpenStax College This work is produced by OpenStax-CNX and licensed under the Creative Commons Attribution License 4.0 By the end of this section, you

More information

Section Four: Pulmonary Artery Waveform Interpretation

Section Four: Pulmonary Artery Waveform Interpretation Section Four: Pulmonary Artery Waveform Interpretation All hemodynamic pressures and waveforms are generated by pressure changes in the heart caused by myocardial contraction (systole) and relaxation/filling

More information

ELECTROCARDIOGRAPHY (I) THE GENESIS OF THE ELECTROCARDIOGRAM

ELECTROCARDIOGRAPHY (I) THE GENESIS OF THE ELECTROCARDIOGRAM ELECTROCARDIOGRAPHY (I) THE GENESIS OF THE ELECTROCARDIOGRAM Scridon Alina, Șerban Răzvan Constantin 1. Definition The electrocardiogram (abbreviated ECG or EKG) represents the graphic recording of electrical

More information

I. INTRODUCTION CHAOS VOLUME 14, NUMBER 1 MARCH 2004

I. INTRODUCTION CHAOS VOLUME 14, NUMBER 1 MARCH 2004 CHAOS VOLUME 14, NUMBER 1 MARCH 2004 The role of M cells and the long QT syndrome in cardiac arrhythmias: Simulation studies of reentrant excitations using a detailed electrophysiological model Hervé Henry

More information

Anaerobic and Aerobic Training Adaptations. Chapters 5 & 6

Anaerobic and Aerobic Training Adaptations. Chapters 5 & 6 Anaerobic and Aerobic Training Adaptations Chapters 5 & 6 Adaptations to Training Chronic exercise provides stimulus for the systems of the body to change Systems will adapt according to level, intensity,

More information

The mhr model is described by 30 ordinary differential equations (ODEs): one. ion concentrations and 23 equations describing channel gating.

The mhr model is described by 30 ordinary differential equations (ODEs): one. ion concentrations and 23 equations describing channel gating. On-line Supplement: Computer Modeling Chris Clausen, PhD and Ira S. Cohen, MD, PhD Computer models of canine ventricular action potentials The mhr model is described by 30 ordinary differential equations

More information

Lab #6: Neurophysiology Simulation

Lab #6: Neurophysiology Simulation Lab #6: Neurophysiology Simulation Background Neurons (Fig 6.1) are cells in the nervous system that are used conduct signals at high speed from one part of the body to another. This enables rapid, precise

More information

Tachyarrhythmias (fast heart rhythms)

Tachyarrhythmias (fast heart rhythms) Patient information factsheet Tachyarrhythmias (fast heart rhythms) The normal electrical system of the heart The heart has its own electrical conduction system. The conduction system sends signals throughout

More information

Normal Intracardiac Pressures. Lancashire & South Cumbria Cardiac Network

Normal Intracardiac Pressures. Lancashire & South Cumbria Cardiac Network Normal Intracardiac Pressures Lancashire & South Cumbria Cardiac Network Principle Pressures recorded from catheter tip Electrical transducer - wheatstone bridge mechanical to electrical waveform display

More information

Heart Rate and Physical Fitness

Heart Rate and Physical Fitness Heart Rate and Physical Fitness The circulatory system is responsible for the internal transport of many vital substances in humans, including oxygen, carbon dioxide, and nutrients. The components of the

More information

The Action Potential, Synaptic Transmission, and Maintenance of Nerve Function

The Action Potential, Synaptic Transmission, and Maintenance of Nerve Function C H A P T E R 3 The Action Potential, Synaptic Transmission, and Maintenance of Nerve Function Cynthia J. Forehand, Ph.D. CHAPTER OUTLINE PASSIVE MEMBRANE PROPERTIES, THE ACTION POTENTIAL, AND ELECTRICAL

More information

Smooth Muscle. Learning Objectives.

Smooth Muscle. Learning Objectives. Smooth Muscle. Learning Objectives. At the end of this course, you should be able to : 1. describe the structure of smooth muscle 2. describe where smooth muscle occurs within the body 3. discuss the structural

More information

Student Academic Learning Services Page 1 of 8 Nervous System Quiz

Student Academic Learning Services Page 1 of 8 Nervous System Quiz Student Academic Learning Services Page 1 of 8 Nervous System Quiz 1. The term central nervous system refers to the: A) autonomic and peripheral nervous systems B) brain, spinal cord, and cranial nerves

More information

Ion Channels. Graphics are used with permission of: Pearson Education Inc., publishing as Benjamin Cummings (http://www.aw-bc.com)

Ion Channels. Graphics are used with permission of: Pearson Education Inc., publishing as Benjamin Cummings (http://www.aw-bc.com) Ion Channels Graphics are used with permission of: Pearson Education Inc., publishing as Benjamin Cummings (http://www.aw-bc.com) ** There are a number of ion channels introducted in this topic which you

More information

Chapter 11: Functional Organization of Nervous Tissue

Chapter 11: Functional Organization of Nervous Tissue Chapter 11: Functional Organization of Nervous Tissue Multiple Choice 1. The nervous system A) monitors internal and external stimuli. B) transmits information in the form of action potentials. C) interprets

More information

ECG Signal Analysis Using Wavelet Transforms

ECG Signal Analysis Using Wavelet Transforms Bulg. J. Phys. 35 (2008) 68 77 ECG Signal Analysis Using Wavelet Transforms C. Saritha, V. Sukanya, Y. Narasimha Murthy Department of Physics and Electronics, S.S.B.N. COLLEGE (Autonomous) Anantapur 515

More information

Catheter Ablation. A Guided Approach for Treating Atrial Arrhythmias

Catheter Ablation. A Guided Approach for Treating Atrial Arrhythmias Catheter Ablation A Guided Approach for Treating Atrial Arrhythmias A P A T I E N T H A N D B O O K This brochure will provide an overview of atrial arrhythmias (heart rhythm problems affecting the upper

More information

the basics Perfect Heart Institue, Piyavate Hospital

the basics Perfect Heart Institue, Piyavate Hospital ECG INTERPRETATION: the basics Damrong Sukitpunyaroj MD Damrong Sukitpunyaroj, MD Perfect Heart Institue, Piyavate Hospital Overview Conduction Pathways Systematic Interpretation Common abnormalities in

More information

BIOPHYSICS OF NERVE CELLS & NETWORKS

BIOPHYSICS OF NERVE CELLS & NETWORKS UNIVERSITY OF LONDON MSci EXAMINATION May 2007 for Internal Students of Imperial College of Science, Technology and Medicine This paper is also taken for the relevant Examination for the Associateship

More information

Understanding the Electrocardiogram. David C. Kasarda M.D. FAAEM St. Luke s Hospital, Bethlehem

Understanding the Electrocardiogram. David C. Kasarda M.D. FAAEM St. Luke s Hospital, Bethlehem Understanding the Electrocardiogram David C. Kasarda M.D. FAAEM St. Luke s Hospital, Bethlehem Overview 1. History 2. Review of the conduction system 3. EKG: Electrodes and Leads 4. EKG: Waves and Intervals

More information

Introduction to Electrophysiology. Wm. W. Barrington, MD, FACC University of Pittsburgh Medical Center

Introduction to Electrophysiology. Wm. W. Barrington, MD, FACC University of Pittsburgh Medical Center Introduction to Electrophysiology Wm. W. Barrington, MD, FACC University of Pittsburgh Medical Center Objectives Indications for EP Study How do we do the study Normal recordings Abnormal Recordings Limitations

More information

Circulatory System Review

Circulatory System Review Circulatory System Review 1. Draw a table to describe the similarities and differences between arteries and veins? Anatomy Direction of blood flow: Oxygen concentration: Arteries Thick, elastic smooth

More information

Blood Pressure Regulation

Blood Pressure Regulation Blood Pressure Regulation Graphics are used with permission of: Pearson Education Inc., publishing as Benjamin Cummings (http://www.aw-bc.com) Page 1. Introduction There are two basic mechanisms for regulating

More information

INTERNATIONAL CONFERENCE ON HARMONISATION OF TECHNICAL REQUIREMENTS FOR REGISTRATION OF PHARMACEUTICALS FOR HUMAN USE S7B

INTERNATIONAL CONFERENCE ON HARMONISATION OF TECHNICAL REQUIREMENTS FOR REGISTRATION OF PHARMACEUTICALS FOR HUMAN USE S7B INTERNATIONAL CONFERENCE ON HARMONISATION OF TECHNICAL REQUIREMENTS FOR REGISTRATION OF PHARMACEUTICALS FOR HUMAN USE ICH HARMONISED TRIPARTITE GUIDELINE THE NON-CLINICAL EVALUATION OF THE POTENTIAL FOR

More information

CHAPTER 2 ANATOMY AND PHYSIOLOGY OF UTERUS AND FOETAL HEART

CHAPTER 2 ANATOMY AND PHYSIOLOGY OF UTERUS AND FOETAL HEART 10 CHAPTER 2 ANATOMY AND PHYSIOLOGY OF UTERUS AND FOETAL HEART the foetal heart. This chapter describes the anatomy and physiology of the uterus and 2.1 ANATOMY OF THE UTERUS The uterus is a pear shaped

More information

Practical class 3 THE HEART

Practical class 3 THE HEART Practical class 3 THE HEART OBJECTIVES By the time you have completed this assignment and any necessary further reading or study you should be able to:- 1. Describe the fibrous pericardium and serous pericardium,

More information

Milwaukee School of Engineering Gerrits@msoe.edu. Case Study: Factors that Affect Blood Pressure Instructor Version

Milwaukee School of Engineering Gerrits@msoe.edu. Case Study: Factors that Affect Blood Pressure Instructor Version Case Study: Factors that Affect Blood Pressure Instructor Version Goal This activity (case study and its associated questions) is designed to be a student-centered learning activity relating to the factors

More information

Problem Sets: Questions and Answers

Problem Sets: Questions and Answers BI 360: Neurobiology Fall 2014 Problem Sets: Questions and Answers These problems are provided to aid in your understanding of basic neurobiological concepts and to guide your focus for in-depth study.

More information

Andrew T. Reisner, Gari D. Clifford, and Roger G. Mark

Andrew T. Reisner, Gari D. Clifford, and Roger G. Mark CHAPTER 1 The Physiological Basis of the Electrocardiogram Andrew T. Reisner, Gari D. Clifford, and Roger G. Mark Before attempting any signal processing of the electrocardiogram it is important to first

More information

Atrioventricular (AV) node ablation

Atrioventricular (AV) node ablation Patient information factsheet Atrioventricular (AV) node ablation The normal electrical system of the heart The heart has its own electrical conduction system. The conduction system sends signals throughout

More information

Neurophysiology V. Neurotransmitters and the Autonomic Nervous System: A Modified Loewi s Experiment 2

Neurophysiology V. Neurotransmitters and the Autonomic Nervous System: A Modified Loewi s Experiment 2 Neurophysiology V. Neurotransmitters and the Autonomic Nervous System: A Modified Loewi s Experiment 2 Materials Purpose Latex gloves Bull Frog Dissecting tools MacLab Data Acquisition Equipment and Chart

More information

Biology/ANNB 261 Exam 1 Name Fall, 2006

Biology/ANNB 261 Exam 1 Name Fall, 2006 Biology/ANNB 261 Exam 1 Name Fall, 2006 * = correct answer. 1. The Greek philosopher Aristotle hypothesized that the brain was a) A radiator for cooling the blood.* b) The seat of the soul. c) The organ

More information

Muscles How muscles contract - The Sliding Filament Theory

Muscles How muscles contract - The Sliding Filament Theory Muscles How muscles contract - The Sliding Filament Theory A muscle contains many muscle fibers A muscle fiber is a series of fused cells Each fiber contains a bundle of 4-20 myofibrils Myofibrils are

More information

Teppe Treppe: A staircase increase in tension production after repeated simulation, even though the muscle is allowed to relax between twitches.

Teppe Treppe: A staircase increase in tension production after repeated simulation, even though the muscle is allowed to relax between twitches. Part II, Muscle: Mechanisms of Contraction and Neural Control, Chapter 12 Outline of class notes Objectives: After studying part II of this chapter you should be able to: 1. Discuss how contractile force

More information