AP 110 Fundamentals of Anatomy and Physiology

1. AP 110Fundamentals of Anatomy and Physiology

2. Objectives • Describe the structure and function of the cardiovascular system • List five actions that can be taken for the prevention of heart disease

3. http://www.heartsite.com/html/the_heart_3.html

4. Circulation and the Heart • Circulation: • Continuous • One-way circuit of the blood vessels • Propelled by the heart

5. Location of the Heart • Between the lungs • Left of the midline of the body • In mediastinum • Apex pointed toward left hip • Base pointed toward right shoulder

7. The Pericardium • The sac that encloses the heart • Fibrous pericardium holds heart in place – anchors to the diaphragm and sternum • Serous membrane • Visceral layer (epicardium) • Parietal layer- outer layer • Serous fluid between the 2 layers that allows friction-free movement of the heart as it contracts and relaxes

8. The Heart Wall • Three tissue layers of the heart wall • Epicardium is thin outermost layer • Myocardium is thickest layer and middle layer • Endocardium lines heart’s interior

9. Layers of the heart wall and pericardium. The serous pericardium covers the heart and lines the fibrous pericardium.

10. Myocardium • Special Features: The cardiac muscle is: • lightly striated (striped) • Has a single nucleus cell • Is controlled involuntarily • Has intercalated disks = modified plasma membranes that firmly attach adjacent cells to each other but allow for rapid transfer of electric impulses between them • Has branching muscle fibers – interwoven so that stimulation that causes the contraction of one fiber results in the contraction of a whole group.

13. Blood Flow • 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

14. Divisions of the Heart • Double pump • Right side pumps blood low in oxygen to the lungs => pulmonary circuit • Left side pumps oxygenated blood to remainder of body => systemic circuit

15. The heart as a double pump. The right side of the heart pumps blood through the pulmonary circuit to the lungs to be oxygenated; the left side of the heart pumps blood through the systemic circuit to all other parts of the body.

16. Anatomy • Heart Chambers • Two upper chambers are called atria (receiving chambers)—right and left atria • Two lower chambers are called ventricles (discharging chambers)—right and left ventricles

17. Anatomy • Wall of each heart chamber is composed of cardiac muscle tissue called myocardium • Endocardium—smooth (internal) lining of heart chambers—(inflammation of endocardium is endocarditis)

18. Anatomy • FOUR CHAMBERS • RIGHT ATRIUM: Receives low-oxygen blood from the body • LEFT ATRIUM: Receives high-oxygenated blood from the lungs • RIGHT VENTRICLE: Pumps blood from right atrium  lungs • LEFT VENTRICLE: Pumps oxygenated blood body

19. Septa (wall) • Interventricular septum • Separates the two ventricles • Interatrial septum • Separates the two atria

21. Anatomy • VALVES • Atrioventricular valves [Entrance valves] • Right atrioventricular (AV) valve (tricuspid valve) • Left atrioventricular (AV) valve (bicuspid valve or mitral)

22. Anatomy • VALVES cont. • Semilunar valves [Exit valves] 3. Pulmonary valve 4. Aortic valve

23. Pathway of Blood through the Heart

24. Pathway of blood through the heart. Blood from the systemic circuit enters the right atrium (1) through the superior and inferior venaecavae, flows through the right AV (tricuspid) valve (2), and enters the right ventricle (3). The right ventricle pumps the blood through the pulmonary (semilunar) valve (4) into the pulmonary trunk, which divides to carry blood to the lungs in the pulmonary circuit. Blood returns from the lungs in the pulmonary veins, enters the left atrium (5), and flows through the left AV (mitral) valve (6) into the left ventricle (7). The left ventricle pumps the blood through the aortic (semilunar) valve (8) into the aorta, which carries blood into the systemic circuit.

25. Coronary Circulation • Blood supply to the myocardium via: • Coronary arteries • Coronary veins • Flows through the Right and Left coronary arteries • Brings oxygen and nutrients Blockage of blood flow through the coronary arteries is called “myocardial infarction” [heart attack]

26. Blood vessels that supply the myocardium. Coronary arteries and cardiac veins are shown. (A) Anterior view. (B) Posterior view.

27. Function of the Heart • Left and Right sides work together in “cardiac cycle” ( a complete heartbeat). • Systole = active phase, contraction • Diastole = resting phase

28. Heart Sounds • Two distinct heart sounds in every heartbeat or cycle—“lubb-dubb” • First (lubb) sound is caused by the vibration and closure of AV valves during contraction of the ventricles • Second (dubb) sound is caused by the closure of the semilunar valves during relaxation of the ventricles

29. The cardiac cycle.

30. Cardiac Output • Stroke volume —volume of blood ejected from one ventricle with each beat • Cardiac output —amount of blood that one ventricle can pump each minute; average is about 5 L per minute at rest • Calculating cardiac output : • Cardiac output (CO) • Stroke volume (SV) • Heart rate (HR) • CO = HR x SV

31. Conduction • Automaticity and Irritability are 2 characteristics that affect the functions of the conduction systems of the heart • Automaticity = an inherent ability to contract in a rhythmic pattern • Irritability = if heart muscle cells are removed and placed under a microscope, they continue to beat. In addition, they can respond to a stimulus in the same way that nerve cells do.

32. Conduction System • Electrical energy stimulates heart muscle • Nodes • Sinoatrial (SA) node (pacemaker) • Atrioventricular (AV) node • Specialized fibers • Atrioventricular bundle (bundle of His) • Purkinje fibers (conduction myofibers) • Intercalated disks

33. Conduction system of the heart. The sinoatrial (SA) node, the atrioventricular (AV) node, and specialized fibers conduct the electrical energy that stimulates the heart muscle to contract. ZOOMING IN • What parts of the conduction system do the internodal pathways connect?

34. Conduction system • 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 • Right and left bundle branches

35. Conduction system • Purkinje fibers —located in the walls of the ventricles • Intercalated disks are electrical connectors that join all the cardiac muscle fibers in a region together so that they receive their impulse, and thus contract, at about the same time

36. The Conduction Pathway Sinus rhythm • Sinoatrial (SA) node • Atria • Atrioventricular (AV) node • Internodal pathways • Bundle of His • Bundle branches and Purkinje fibers • Ventricles

37. Control of the Heart Rate • Influences that allow heart to meet changing needs rapidly: • Autonomic nervous system (ANS) • Sympathetic nervous system • Parasympathetic system • Cranial nerve X • Hormones

38. Variation in Heart Rates • Bradycardia – pulse rate < 60bpm • Tachycardia – pulse rate 100-150bpm + • Sinus arrhythmia – alteration in formation of impulses through the SA Node to the rest of the heart • Premature beat (extrasystole)

39. The Aging Heart • Shrinkage • Decreased contraction strength • Valves become less flexible • Murmur develops • Cardiac output decreases • Abnormal rhythms may develop • Heart block

40. Prevention of Heart Disease • Non-modifiable risk factors • Age • Gender • Heredity • Body type

41. Prevention of Heart Disease • Modifiable risk factors • Smoking • Physical inactivity • Weight • Saturated fat in diet • Hypertension • Diabetes and gout

42. Heart Studies • Assessment, ausculatation • EKG • Cardiac catheterization • Echocargiogram • Holter Monitor