1. Circulatory System

2. Location and projection of heart 5 inch, cone shaped 3.5 inches wide, 2.5 inches thick Rests on diaphragm in the mediastinum 2/3 on left of midline Apex (pointed side of heart) is anteriorly, inferiorly, and to the left Base (large side of heart) is posteriorly, superiorly, and to the right

3. Location and projection continued Anterior surface is deep to the sternum and ribs Inferior surface rests on diaphragm and is between the apex and right border Right border 1.faces right lung 2. extends from inferior surface to base Left border 1. faces left lung 2. extends from base to apex

5. Structure and function of the heart Pericardium 1. surrounds and protects 2. confines the heart to midiastinum, while allowing for movement 3. Fiberous pericardium a. superficial layer b. dense, irregular connective tissue c. rests on and is attached to diaphragm d. provides protection, anchors heart

6. Structure and function continued 4. serous pericardium a. forms a double layer around heart b. parietal layer is fused with fiberous pericardium c. visceral layer attaches to surface of the heart

7. Structure and function continued Pericardial cavity 1. space between parietal and visceral layer of the serous pericardium 2. Pericardial fluid a. secretion of pericardial cells b. located in pericardial cavity c. reduces friction of the membrane as the heart moves

8. Layers of the heart wall Epicardium 1. thin, transparent outermost layer 2. gives heart its smooth texture Myocardium 1. middle layer 2. composed of cardiac muscle tissue Endocardium 1. innermost layer 2. provides a smooth lining for heart chambers

10. Chambers of the heart Atria (upper chambers) Ventricles (lower chambers) Auricles a. on anterior surface of atria b. slightly increase volume of atria Suci a. grooves that contain coronary blood vessels b. each marks boundaries of heart chambers

12. Chambers of the heart continued Right atrium a. forms right border of heart b. recieves blood from three veins: Superior vena cava, inferior vena cava, and Coronary sinus Separated from left atrium by interatrial septum Tricuspid valve a. allows blood to flow from right atria to to right ventricle b. consists of three cusps

14. Chambers of the heart continued Right ventricle a. forms most of anterior surface b. Trabeculae Carneae 1. raised bundles of cardiac muscle 2. convey part of the conduction system of the heart c. Chordae tendineae 1. attach to cusps of tricuspid valves 2. attach to trabeculae Carneae

16. Chambers of the heart continued Right ventricle continued d. separated from left ventricle by interventricular septum e. Blood enters pulmonary semilunar valve into pulmonary trunk of right and left pulmonary arteries

18. Chambers of the heart continued Left atria 1. Forms most of the base of the heart 2. receives blood from the lungs through pulmonary veins 3. blood passes into left ventricle through the bicuspid valve

20. Chambers of the heart continued Left ventricle 1. forms apex of heart 2. Also contains trabeculae carneae 3. Blood passes from left ventricle through aortic semilunar valve into ascending aorta 4. Some blood flows into Coronary arteries 5. Remainder of blood flows into arch of the aorta and descending aorta

22. Myocardial thickness and function Atria are thin walled because they deliver blood to adjacent ventricles Left ventricle has largest wall because it pumps blood to the body Even though the right ventricle pumps the same amount of blood simultaneously as the left ventricle, the lungs offer little resistance so its wall is much smaller

23. Operation of heart valves Atrioventricular valves 1. bicuspid and tricuspid valves 2. when opened pointed end of cusps project into ventricle 3. They open when ventricular pressure is less than atrial pressure 4. When ventricles contract, they drive the cusps upward until they close 5. Chordae Tendinae prevent cusps from everting

24. Operation of heart valves continued Semilunar valves 1. Allow ejection of blood into arteries but prevents backflow 2. Consists of three crescent shaped cusps 3. When ventricles contract valves open 4. pressure from backflow causes them to close

26. Circulation of blood Systemic circulation 1. Left side of heart 2. Receives blood from lungs 3. pumps blood through arteries to all parts of body 4. Arteries give rise to arterioles, which lead to systemic capillaries 5. Blood flows through one capillary and enters a venule 6. Venules carries blood to veins and back to heart

27. Circulation of Blood Continued Pulmonary circulation 1. Right side of heart 2. Blood ejected from right ventricle flows into pulmonary arteries 3. Blood flows through pulmonary veins to left atria

29. Circulation of blood continued Coronary circulation 1. Blood can not diffuse through all layers of the heart 2. Small amount of blood flows through coronary arteries which branch from ascending aorta 3. High aortic pressure pushes blood through arteries, into capillaries, and into coronary veins when the heart is at rest

31. Conduction system of the heart Autorhythmic cells 1. Cardiac muscle fibers that are self excitable 2. allows heart to be removed for transplants 3. act as pacemakers 4. form the conduction system ( the route for (propagating action potentials)

32. Components of conduction system Sinoatrial (SA) node 1. begins cardiac excitation 2. located in right atria Ateroventricular (AV) node 1. receives action potential from SA node 2. Located in septum of atria

33. Components of conduction system continued AV bundle or bundle of his 1. only electrical connection of atria and ventricles 2. Potential enters left and right branches that lead to apex of the heart Purkinje Fibers 1. Conduct action potential through ventricular myocardium 2. causes ventricles to contract about.20 seconds after atria