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Basic Principles of the Cardiovascular System

This course covers the anatomy of the heart, the pumping mechanism, blood flow through the heart, and the components of the conduction system. It also explores the structure and function of cardiac cells and the generation of electrical impulses.

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Basic Principles of the Cardiovascular System

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  1. Basic Principles of the Cardiovascular System Patient Care Techncian

  2. Objectives • Describe the structures of the heart. • Explain the pumping mechanism of the heart and the path of blood flow through the heart. • Distinguish between pulmonary circulation and systemic circulation. • List the components of the conduction system and the sequence of impulse origination. • State four properties of cardiac cells.

  3. Anatomy of the Heart • 4 chambered pump • Weighs less than 1 pound • Size of closed fist • Located in mediastinum – between lungs, sternum, spine

  4. Chambers

  5. Valves

  6. Question • The right side of the heart pumps just as much blood as the left side – why are the walls of the right side thinner than those of the left?

  7. Where are these valves? • Tricuspid valve • Mitral valve • Pulmonary semilunar valve • Aortic valve

  8. Chordae tendoneae

  9. Heart Layers

  10. Heart Layers • Endocardium – layer of smooth cells that line heart • Myocardium – layer of muscle that cause contraction (myocardial infarction) • Epicardium – fatty layer that protects heart • Pericardial sac – holds heart in place, reduces friction of beat

  11. Circulation • Pulmonary • Systemic • Coronary

  12. Pulmonary Circulation

  13. Pulmonary Circulation

  14. Systemic Circulation

  15. Coronary Circulation

  16. Coronary Circulation

  17. Anterior (A) and posterior (B) views of epicardial coronary circulation. LAD indicates left anterior descending coronary artery; AIV, anterior interventricular vein; CFX, circumflex coronary artery; RCA, right coronary artery; GCV, great cardiac vein; PDA, posterior descending artery; CS, coronary sinus; MCV, middle coronary vein; and SCV, small coronary vein. Coronary Circulation

  18. Question • Where and when do coronary arteries fill?

  19. Coronary Sinus

  20. Blood Vessels • Define the following: • Artery • Arteriole • Vein • Venule • Capillary • Aorta • Vena Cava • Pulmonary artery • Pulmonary vein

  21. Question • What vessels, structures and/or organs are included in each type of circulation?

  22. Question • Show the path of a drop of blood from the right atrium back to the right atrium. • Be sure to include major vessels, organs, and valves.

  23. Cardiac cycle • Series of events that constitute complete heartbeat • Atrial systole - Contraction of atria to pump blood to ventricles • Ventricle systole – contraction of ventricles to pump blood to body • Atrial diastole – the atria begin refilling during ventricular systole • Ventricular diastole – blood from the atria begins refilling the ventricles during atrial systole.

  24. Conduction Pathways • Network of conducting tissue • Specialized cells – do not contract • Initiates each heartbeat and controls rhythm

  25. Sinoatrial Node • Located in right atrium • Main cardiac pacemaker • Normally generates impulses at rate of 60 to 100 beats per minute

  26. Atrioventricular Node • Receives impulse via internodal pathways • Located in floor of atrium near septum • Delay the impulse to allow ventricular filling • Intrinsic rate 40 to 60 • Two basic functions • Protect ventricles from fast heart rate that may originate in atrium • Serves as pacemakers if SA node fails

  27. AV Bundle or Bundle of His • Conducts impulse from AV Node • Divides into right and left bundle branches at intraventicular septum • Right bundle branch supplies right ventricle • Left bundle branch splits • Anterior supplies upper portion of left ventricle • Posterior supplies lower portion of left ventricle

  28. Purkinje Fibers • Enlarged fibers • Spread along septum toward apex and over lateral walls of ventricles • Work with Bundle of His and bundle branches to contract ventricles • Intrinsic rate 20 to 40 • May act as backup pacemaker

  29. Cardiac Electrical System

  30. Cool Website! • http://science.howstuffworks.com/environmental/life/human-biology/heart4.htm

  31. Special Properties of Cardiac Cells • Automaticity – ability to generate own impulse and maintain rhythmic activity • Excitability – ability of all heart cells to respond to impulse • Conductivity – cardiac cell able to relay impulse to neighboring cells and create wave of excitation • Contractility – ability to respond to electrical impulse with pumping action

  32. Two Types of Cardiac Cells • Capable of contraction • Capable of conduction

  33. Contraction of the Heart • Cell membrane must be electrically activated • Depolarization - Positive ions move into cell and negative ions move out of cell • Repolarization – negative ions return to inside of cell and positive ions move out of cell • This movement of ions is recorded by EKG

  34. Cardiac Terminology

  35. EKG Representation of Heartbeat

  36. The Normal Electrocardiogram

  37. Objectives • Explain how electrical current in the heart is generated • Differentiate between EKG waves, segments, intervals, and complexes • Describe how the movement of electricity through the heart produces predictable wave patterns • Describe the method of detection and recording of these wave patterns by the EKG machine

  38. Detection and Recording • Transmembrane potential – electrical difference between the inside and outside of the cell • Action potential – changes that occur during the process of depolarization and repolarization within a cell as activated by electrical impulse • Refractory period – time during which the cell is unable to respond to a stimulus • Vector – path of impulse displaying the direction and magnitude of the electrical current

  39. Normal Heart • Vector proceeds in same sequence • Vector is predictable

  40. EKG machine • Writing arm • Recording device (galvanometer) • Stylus needle responds by heat or pressure • Lead wires • Attaches electrodes to machine • Electrodes • Provides direct contact with skin

  41. EKG • Tracing of electrical voltage produced by continual depolarization and repolarization of heart • Shows direction and magnitude of electrical current produced by the heart

  42. Waves Deflections from the baseline Designated as: P, QRS, T

  43. Waves • P wave – depolarization of atria • Q wave – (may be absent) activation in intraventicular septum, first negative deflection of QRS • R wave – impulse progression through right and left ventricles, first upward deflection of QRS • S wave – completion of left ventricular activation • T wave – repolarization of ventricles

  44. Waves

  45. Segments • Straight lines or spaces between waves • ST segment • Measured from end of S wave to beginning of T wave • 0.35 to 0.45 seconds • Isoelectric (flat)

  46. Segments

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