1. Heart Seatwork The heart rests on the _________ surface of the diaphragm. It lies___________ to the vertebral column and __________to the sternum. The base of the heart points to the _______ shoulder and the apex points inferiorly toward the _______hip.

2. The heart rests on the superior surface of the diaphragm. It lies anterior to the vertebral column and posterior to the sternum. The base of the heart points to the right shoulder and the apex points inferiorly toward the left hip.

3. The Heart

4. double pump (blood enters & leaves twice in one circuit)

5. 1. Size & Location a. size—(average adult) about 5.5” long & 3.5” wide b. location—mediastinal cavity 1) Between lungs, under sternum 2) Apex: left side; between 5 th & 6 th ribs

6. 2. coverings—double layered, serous, membranous pericardium a.Visceral pericardium (epicardium) directly against heart b.Parietal pericardium—on the outside c.Pericardial cavity—between 2 layers

7. 3. Wall of heart (3 layers) a. epicardium—outer, serous layer. Thin b. myocardium—middle, thick layer –Cardiac muscle c. Endocardium—inner, epithelium & connective tissue –Continuous with inner lining of blood vessels

9. 4. Chambers and vessels a. 4 chambers or cavities 1) two atria—right and left a) receive blood from veins b) thin walls & “earlike” auricles project out 2) two ventricles—right and left a) pump blood out into arteries b) thick walls 3) septum—separates heart into right and left (divides atria & ventricles)

10. b. vessels—veins enter heart, arteries leave heart 1) veins—enter atria a) superior & inferior vena cava bring blood from body→right atrium; superior from upper body regions; inferior from lower. b) Coronary sinus—wall of heart into right atrium c) Pulmonary veins—enter left atrium from lungs

11. 2) arteries—leave ventricles a)pulmonary artery—pumps blood from right ventricle to lungs b)aorta—pumps blood from left ventricle to body

12. 5.Valves of the heart (4) a.Atrioventricular valves—between atria & ventricles—function: to prevent backflow into atria 1)Tricuspid valve—right side 2)Bicuspid valve (mitral valve)—left side --both valves are composed of flaps (cusps) to which the chordae tendineae attach on the lower surface to keep the cusps in position --papillary muscles attach to chordae tendinae & keep them taut.

13. b. Semilunar valves—between ventricles and arteries—function: to prevent backflow into ventricles 1)Pulmonary semilunar—between right ventricle & pulmonary artery 2)Aortic semilunar—between left ventricle & aorta

16. 6. Path of Blood through the HeartBlood a. Oxygen poor blood returns to the right atrium via the vena cavae and coronary sinus. b. The right atrium contracts, forcing blood through the tricuspid valve into the right ventricle.

17. c.The right ventricle contracts, closing the tricuspid valve, and forcing blood through the pulmonary valve into the pulmonary trunk and arteries. d.The pulmonary arteries carry blood to the lungs where it gets rid of carbon dioxide and picks up a new supply of oxygen.

18. e.Freshly oxygenated blood is returned to the left atrium of the heart through the pulmonary veins. f.The left atrium contracts, forcing blood through the left bicuspid valve into the left ventricle.

19. g.The left ventricle contracts, closing the bicuspid valve and forcing open the aortic valve as blood enters the aorta for distribution to the body. Copyright  The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

20. 7. Blood supply to heart a.Main supply—right & left coronary artery b.Drained by cardiac veins

21. Copyright  The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

23. Seatwork Name the pathway blood takes through the heart. (Try it without notes) Start with the vena cavae (plural) and end with the systemic (body) circuit. Pick up RQ1: Heart –Due Friday

24. 8. Fetal Adaptations a.Foramen ovale—opening in the atrial septum a.(fetal adaptation that allows oxygenated blood to enter the left atrium from the right)

25. 8. Fetal AdaptationsAdaptations a.Ductus arteriosus: fetal adaptation that prevents blood that enters the right ventricle from entering the pulmonary circuit; protects lungs and lets ventricle become strong

26. 9. Heart actions a.Cardiac cycle (3 phases) 1)Atrial & ventricular diastole 2)Atrial systole & ventricular diastole 3)Ventricular systole & atrial diastole Diastole = relaxation Systole = contraction

27. --heart sounds: closing of valves— 1 st one is closing of AV valves as ventricles contract (lubb) 2 nd one is closing of semilunar valves when ventricles relax (dubb)

28. b. Cardiac muscle fibers 1) fibers interconnected, called functional syncytium; function is to conduct impulses synchronously 2) two in heart: (a) atrial syncytium—wall of atrium (b) ventricular syncytium—walls of ventricles (c) two connected at floor of right atrium by fibers of the cardiac conduction system

29. c. Cardiac conduction system—coordinates cardiac cycle (1) specialized muscle fibers initiate & distribute impulses (2) sinoatrial node (S-A node); key portion. Where heartbeat is initiated

30. Cardiac conduction system: S-A node –(a) location; wall of right atrium near superior vena cava –(b) excite themselves without outside stimulation –(c) rhythmic –(d) also called pacemaker –(e) impulses leave S-A node, travel through walls

31. –(f) right and left atria contract simultaneously –(g) impulses lead into atrioventricular (A-V) node—impulse can’t travel directly to ventricles

32. –(3) A-V node—floor of right atrium (a) only pathway between atrial & ventricular syncytia (b) delay as impulses pass into node & out of it (c) move from node into A-V bundle (Bundle of His) –it travels into the ventricular septum and branches into a left & right branch (d) branches give rise to Purkinje fibers which actually distribute impulses to the ventricular myocardia

33. –(4) Purkinje fibers (a) muscle fibers in ventricular walls are arranged in irregular whorls, contract in twisting motion (b) contraction starts at apex & moves upward

34. Video clip & ECGclip

35. What is another name for the visceral pericardium of the heart?

36. Answer The Epicardium

37. Body fluids conduct electrical currents

38. d. electrocardiogram (ECG) –(1) records changes in electrical activity of myocardium during cardiac cycle (body fluids conduct electrical currents) –(2) electrodes placed on skin; machine records activity Depolarization & repolarization in fibers Forms waves

39. –(3) waves (a) P wave—depolarization of atria (b) QRS complex—depolarization of ventricles (c) T wave—repolarization of ventricles

40. Normal ECG (sinus rhythm)ECG

42. –(4) abnormal recordings (a) auricular fibrillation –i. no distinct P wave –ii. Atria do not distinctly contract (flutter, 200-400/min) (b) delayed conduction –i. greater time period between P & QRS complex –ii. From 0.2 up to 0.5 seconds

43. ECG Interpretation Graph paper that the ECG records on is standardized to run at 25mm/second Paper is marked at 1 second intervals on the top and bottom. The horizontal axis correlates the length of each electrical event with its duration in time. Each small block (defined by lighter lines) on the horizontal axis represents 0.04 seconds. Five small blocks (shown by heavy lines) is a large block, and represents 0.20 seconds.

44. ??

45. Examples of Abnormal ECGs: http://www.ambulancetechnicianstudy.co.u k/rhythms.htmlhttp://www.ambulancetechnicianstudy.co.u k/rhythms.html

46. e. regulation of cardiac cycle –(1) rate increased in response to need –(2) changes often involve factors which affect the pacemaker –(3) cardiac center in medulla maintains a balance between parasympathetic and sympathetic impulses reaching the heart, or increases in one or the other. (accelerate or inhibit the heart rate)

47. (a) parasympathetic fibers innervate S-A and A-V nodes –i. nerve endings release acetylcholine –ii. Decreases heart rate (braking action) –Iii. Less impulses release brake, speeds up rate (b) sympathetic fibers innervate nodes by way of accelerator nerves –i. endings release norepinephrine –ii. Increases rate & force of myocardial contractions

48. (c) cardiac center receives sensory impulses from various areas and responds accordingly –i. pressoreceptors ( aka. baroreceptors) in aortic arch & carotid sinus are sensitive to changes in blood pressure; if high, parasympathetic impulses slow rate to drop pressure –ii. Also opposite effect –(4) affect of temperature (a) hypothermia—low temperature slows rate (b) increased temperature increases rate

49. –(5) affect of ions (a) excess of K +, hyperkalemia (decrease in rate and force of contraction) –Decrease in K +, hypokalemia (abnormal rhythm, arrhythmia) (b) excessive Ca ++, hypercalcemia (increased rate or prolonged contraction) –Low Ca ++, hypocalcemia (depresses heart action, inhibits heart rate)