Electrical Activity of Heart
Presentation by:Tarique AhmadJohn FrostGrant PostIan Osborne
Introduction VideoCardiac Conduction System:http://www.youtube.com/watch?v=zdoSreUAthA
Conducting System• also known as cardiac conducting
system or the nodal system• its a network of specialized cardiac
muscle cells that initiates and distributes electrical impulses
• includes:o Sinoatrial (SA) Nodeo Atrioventricular (AV) Nodeo Conducting Cells
Bundle of his (hiss )/ Atrioventricular (AV) Bundle Purkinje Fibers
Continued...• conducting system allows heart to be
automaticity, or autorhythmicityo it contracts on its own, in absence of neural
and hormonal stimulation• actual contraction lags behind the
electrical pulseo due to time is takes calcium ions to enter the
sarcoplasm
http://www.ceufast.com/courses/239/04_Cardiac_Conduction_System.jpg
Sinoatrial (SA) Node• In the upper part of the right atrium• specialized bundle of neurons known
as the sinoatrial node (SA node)• Acting as the heart's natural
pacemaker, o "fires" at regular intervals to cause the heart
to beat at a rhythm of 60 to 70 beats per minute
AV / Atrioventricular Node• Specialized Cardiocytes relay the
contractile stimulus to the AV bundle, the bundle branches, the Purkinje fibers, and the ventricular myocardium
• Located between the atria and the ventricles
• There's a 100 millisecond delay once signal is received at AV node
= 100 millisecond long delay
Lasts a total of 225 Milliseconds
http://washingtonhra.com/16.html
Conducting Cells: Bundle of His
• Also known as the AV bundle
• Carry the contracting stimulus from the AV node to the Purkinje Fibers
• Separates into left and right bundle branches, which are spread across the inner surfaces of the left and right
http://www.ambulancetechnicianstudy.co.uk/card.html#.UXHG16KsiSo
Conducting Cells: Purkinje Fibers• Located in the inner ventricle walls of the heart
just below the epicardium• Assist the conduction system in the
synchronization of contractions• Carry the electrical impulses from the Sinoatrial
Node to the Myocardium• Conduct action potentials
Electrocardiogram (ECG/EKG)• graphic record of heart, monitored by
electrical activity of heart at certain locations
• Electrical events of heart are powerful enough to be detected by electrodes on body surface
http://smartmedicalindo.com/product_images/w/452/Schiller_Cardiovit_AT-10_Plus_EKG_Machine__22732_zoom.jpg
Continued...• comparing information from different
locations to monitor and check performance of hearto specific components can be checked as well
• tracing varies on placement of electrodes, also called leads
• used to detect cardiac arrhythmiaso abnormal cardiac activity
Understanding an ECG/EKG• P Wave- small wave that accompanies
depolarization of atria• QRS Complex- wave that appears after
contraction of ventricleso ventricles begin contraction at peak of R wave
• T Wave- small wave that indicates ventricular repolarization
http://www.usfca.edu/fac-staff/ritter/Image20.gif
Analyzing an EKG• involves measuring size of voltage
changes• determining temporal relations
between components• focus on amount depolarization during
P wave and QRS complex
POP QUIZ!!!1.What is the pacemaker of the heart?
a. Where is it located?2.What does AV stand for?
a. Where is the node located?3.What does the bundle of hiss do?4.Where are the Purkinje Fibers located?5.What does ECG/EKG stand for?
Works CitedMartini, Frederic H., and Edwin F. Bartholomew. Essentials of
Anatomy and Physiology. 4th ed. San Francisco: Pearson,2007. Print.
Martini, Frederic H., and Judi L. Nath. Fundamentals of Anatomy andPhysiology. 8th ed. San Francisco: Prentice Hall, 2009. Print.