1. Chapter 14
The Heart

2. Anatomy and Blood Flow in the Heart
Lesson 14.1
Anatomy and Blood Flow in the Heart
Discuss the location, size, and position of the heart in the thoracic cavity and identify the heart chambers, valves and their major disorders, and sounds.
Trace blood through the heart, compare the functions of the heart chambers on the right and left sides, and explain how a myocardial infarction might occur.

3. Location, Size, & Position of the Heart
Triangular organ located in mediastinum with two-thirds of the mass to the left of the body midline and one-third to the right; the apex is on the diaphragm
Shape and size of a closed fist

4. The Heart

5. Cardiopulmonary Resuscitation (CPR)
Heart lies between the sternum in front and the bodies of the thoracic vertebrae behind
Rhythmic compression of the heart between the sternum and vertebrae can maintain blood flow during cardiac arrest
If combined with artificial respiration procedure, it can be lifesaving

6. Anatomy of the Heart Heart chambers
Two upper chambers are called atria (receiving chambers)—right and left atria
Two lower chambers called ventricles (discharging chambers)—right and left ventricles

7. Heart Chambers
Wall of each heart chamber is composed of cardiac muscle tissue called myocardium
Endocardium—smooth lining of heart chambers
Inflammation of endocardium is called endocarditis
Inflamed endocardium can become rough and abrasive and thereby cause a thrombus

8. The Pericardium and Pericarditis
Pericardium—two-layered fibrous sac with a lubricated space between the two layers
Inner layer is called visceral pericardium or epicardium
Outer layer called parietal pericardium
Pericarditis—inflammation of the pericardium
Cardiac tamponade—compression of the heart caused by fluid building up between the visceral pericardium and parietal pericardium

9. An Internal View of the Heart

10. Heart Action Contraction of the heart is called systole
Relaxation of the heart is called diastole

11. Heart Action

12. Heart Valves
Valves keep blood flowing through the heart; prevent backflow
Atrioventricular (AV) valves
Tricuspid—at the opening of the right atrium into the ventricle
Bicuspid (mitral) —at the opening of the left atrium into the ventricle

13. Semilunar (SL) Valves
Pulmonary semilunar—at the beginning of the pulmonary artery
Aortic semilunar—at the beginning of the aorta

14. Valve Disorders
Incompetent valves “leak,” allowing some blood to flow backward into the chamber from which it came
Stenosis- valves are narrower than normal, reducing blood flow
Rheumatic heart disease—cardiac damage resulting from a delayed inflammatory response to streptococcal infection
Mitral valve prolapse (MVP)—incompetence of mitral valve caused by its edges extending back into the left atrium when the left ventricle contracts

15. Mitral Valve Stenosis

16. Mitral Valve Prolapse

17. Heart Sounds
Two distinct heart sounds in every heartbeat, or cycle—“lub-dup”
First sound (lub) caused by the vibration and closure of AV valves during contraction of the ventricles
Second sound (dup) caused by the closure of the semilunar valves during relaxation of the ventricles
Heart murmurs—abnormal heart sounds often caused by abnormal valves

18. Blood Flow Through the Heart
Heart acts as two separate pumps—the right atrium and ventricle performing different functions from the left atrium and ventricle

19. Blood Flow Through the Cardiovascular System

20. Sequence of Blood Flow
Venous blood enters the right atrium through the superior and inferior venae cava—passes from the right atrium through the tricuspid valve to the right ventricle
From the right ventricle through the pulmonary semilunar valve to the pulmonary artery to the lungs—blood from the lungs to the left atrium, passes through the bicuspid (mitral) valve to left ventricle
Blood in the left ventricle is pumped through the aortic semilunar valve into the aorta and is distributed to the body as a whole

21. Coronary Circulation
Blood, which supplies oxygen and nutrients to the myocardium of the heart, flows through the right and left coronary arteries
Blockage of blood flow through the coronary arteries can cause myocardial infarction (heart attack)

22. Coronary Circulation

23. Blood vessels that supply the myocardium23

24. Coronary Heart Disease
Coronary thrombosis and coronary embolism involve a blood clot blocking some part of a coronary artery
Blood cannot flow through to the heart, and those cells start to die
Myocardial infarction (MI), or tissue death, occurs

25. Coronary Heart Disease, Cont'd.
Atherosclerosis—type of “hardening of arteries” in which lipids build up on the inside wall of blood vessels; can partially or totally block coronary blood flow
Angina pectoris—chest pain caused by inadequate oxygen to the heart

26. Treatment of Heart Disease
Coronary angioplasty. 26

27. Treatment of Heart Disease (cont.)
Arterial stent. 27

28. Coronary Bypass Surgery
Common treatment for patients with severely restricted coronary artery blood flow
Other veins or vessels are taken from the body and used to bypass blockages in the coronary arteries

29. Prevention of Coronary Artery Disease
Risk Factors for Coronary Artery Disease
Risk Factors That Cannot Be Modified
Risk Factors That Can Be Modified
Age
Smoking and other forms of tobacco use
Gender
Physical inactivity
Heredity
Overweight
Body type
Saturated fat in diet
Hypertension
Type 2 diabetes
Sleep apnea

30. Cardiac Cycle
Heartbeat is regular and rhythmical—each complete beat called a cardiac cycle—average is about 72 beats per minute
Each cycle, about 0.8 seconds long, subdivided into systole (contraction phase) and diastole (relaxation phase)

31. Conduction System of the Heart
Normal structure and function
SA (sinoatrial) node, the pacemaker—located in the wall of the right atrium near the opening of the superior vena cava
AV (atrioventricular) node—located in the right atrium along the lower part of the interatrial septum
AV bundle (bundle of His) —located in the septum of the ventricle
(subendocardial fibers)—located in the walls of Purkinje fibers the ventricles

32. Conduction System of the Heart

33. Conduction System of the Heart

34. Electrocardiography
Specialized conduction system structures generate and transmit the electrical impulses that result in contraction of the heart
These tiny electrical impulses traveling through the heart's conduction system can be picked up on the surface of the body and transformed into visible tracings by a machine called an electrocardiograph
The visible tracing of these electrical signals is called an electrocardiogram, or ECG or EKG

35. ECG Deflections Electrocardiography
The normal ECG has three deflections or waves
P wave—associated with depolarization of the atria
QRS complex—associated with depolarization of the ventricles
T wave—associated with repolarization of the ventricles

36. Events Represented by the Electrocardiogram (ECG)

37. Events Represented by the Electrocardiogram (ECG)

38. Cardiac Dysrhythmia Abnormality of heart rhythm
Heart block—conduction of impulses is blocked
Complete heart block—impaired AV node conduction, producing complete dissociation of P waves from QRS complexes
Can be treated by implanting an artificial pacemaker

39. Dysrhythmia

40. Types of Dysrhythmia
Bradycardia—slow heart rate (less than 60 beats/min)
Tachycardia—rapid heart rate (more than 100 beats/min)
Sinus dysrhythmia—variation in heart rate during breathing cycle
Premature contraction (extrasystole)—contraction that occurs sooner than expected in a normal rhythm
Fibrillation—condition in which cardiac muscle fibers are “out of step,” producing no effective pumping action

41. Fibrillation
Atrial fibrillation—(AF or A-fib) occurs in mitral stenosis, rheumatic heart disease, and infarction of atrial myocardium
Ventricular fibrillation—(VF or V-fib) is life-threatening; occurs when a lack of ventricular pumping stops blood flow to vital tissues
Defibrillation—can treat fibrillation by applying an electric shock to force cardiac fibers back into rhythm

42. AEDs and Atrial Ablation
Automatic external defibrillators (AEDs) are small, lightweight devices that detect heart rhythms and can produce a shock, if necessary
Atrial ablation is used to treat atrial fibrillation by destroying heart muscle in a specific location and eliminating the pathway of abnormal electrical signals

43. Stroke Volume and Cardiac Output
Stroke volume is the volume of blood ejected from one ventricle with each beat
Cardiac output (CO) is amount of blood that one ventricle can pump each minute—average is about 5 L per minute at rest
CO is determined by heart rate (HR) and stroke volume (SV)
HR (beat/min) x SV (volume/beat) = CO (volume/min)

44. Heart Rate (HR)
Autonomic nervous system (ANS) can alter the heart's rhythm to increase or decrease HR
When blood CO2 levels rise due to exercise, HR rises to restore homeostasis of blood gases
Sudden drop in blood pressure can increase HR to restore normal blood flow .

45. Stroke Volume (SV)
The volume of blood ejected by the ventricles is determined by the volume of blood returned to the heart by the veins, or venous return
The higher the venous return, the higher the SV
Strength of myocardial contraction also helps determine SV
Valve disorders, coronary artery blockage, or myocardial infarction can all decrease stroke volume and may decrease cardiac output

46. Cardiac Output

47. Heart Failure
Heart failure—inability to pump enough returned blood to sustain life; it can be caused by many different heart diseases
Right heart failure—failure of the right side of the heart to pump blood, usually because the left side of the heart is not pumping effectively

48. Cor Pulmonale

49. Heart Failure
Left heart failure (congestive heart failure, CHF)—inability of the left ventricle to pump effectively, resulting in congestion of the systemic and pulmonary circulations
Diseased hearts can be replaced by donated living hearts (transplants) or by artificial hearts (implants), although both procedures have yet to be perfected

50. Courtesy Patricia Kane, Indiana University Medical School.
Heart Transplant
Courtesy Patricia Kane, Indiana University Medical School.