1. Copyright © 2012 Wolters Kluwer Health | Lippincott Williams & Wilkins Chapter 22 The Cardiovascular System

2. Copyright © 2012 Wolters Kluwer Health | Lippincott Williams & Wilkins The Cardiovascular System Designed for transportation and communication throughout the body Vital in maintaining homeostasis within the body Composed of the heart and blood vessels Functions –Pumping blood –Transporting gases, nutrients, hormones, and wastes

3. Copyright © 2012 Wolters Kluwer Health | Lippincott Williams & Wilkins The Heart

4. Copyright © 2012 Wolters Kluwer Health | Lippincott Williams & Wilkins The Heart (cont’d) The heart lies in the thoracic cavity in the mediastinal space. Layers of the heart wall –Endocardium –Myocardium –Epicardium

5. Copyright © 2012 Wolters Kluwer Health | Lippincott Williams & Wilkins The Heart (cont’d) The pericardium is a sac that surrounds and protects the heart. –Epicardium portion of the heart wall also makes up the pericardium’s visceral layer. –Parietal layer is the inner serous pericardium. –The space between the visceral and parietal layers is called the pericardial space or cavity. –The outermost layer is called the fibrous pericardium.

6. Copyright © 2012 Wolters Kluwer Health | Lippincott Williams & Wilkins Heart Chambers and Valves Chambers –Atria and ventricles Valves –Atrioventricular valves Tricuspid valve and mitral valve –Overflow valves Semilunar valves: Pulmonic valve and aortic valve

7. Copyright © 2012 Wolters Kluwer Health | Lippincott Williams & Wilkins Heart Chambers and Valves (cont’d) Chordae tendineae –Tendon-like strands attached to tissue flaps of the valves –Anchored to papillary muscles –As the ventricles contract, the papillary muscles also contract at this time, tightening the chordae tendineae, to prevent the valve cusps from everting. If the AV valves, chordae tendineae, or papillary muscles become damaged, backflow of blood (regurgitation) into the atria can occur with ventricular contraction.

8. Copyright © 2012 Wolters Kluwer Health | Lippincott Williams & Wilkins Question Is the following statement true or false? The left ventricle contains the thickest layer of muscles in the heart.

9. Copyright © 2012 Wolters Kluwer Health | Lippincott Williams & Wilkins Answer True The left ventricle must pump strongly enough to send blood out to the entire body. The right ventricle also has thick muscles; the muscles in the atria are thinner than those of either ventricle.

10. Copyright © 2012 Wolters Kluwer Health | Lippincott Williams & Wilkins Route of Blood Flow Through the Heart The right atrium receives venous blood from the body via the superior and inferior vena cavae and the coronary sinus. Blood then passes through the tricuspid valve into the right ventricle. It moves on through the pulmonic valve during ventricular contraction to enter the pulmonary artery and then the lungs, where it exchanges carbon dioxide for oxygen.

11. Copyright © 2012 Wolters Kluwer Health | Lippincott Williams & Wilkins Route of Blood Flow Through the Heart (cont’d) Oxygenated blood returns to the left atrium via four pulmonary veins. It travels through the mitral (bicuspid) valve into the left ventricle. During ventricular contraction, the blood from this chamber exits through the aortic semilunar valve into the aorta and out to the systemic circulation.

12. Copyright © 2012 Wolters Kluwer Health | Lippincott Williams & Wilkins Blood Vessels of the Heart Coronary Arteries –Two coronary arteries branch off the ascending aorta to provide blood to heart muscle. Left coronary artery/left main coronary artery Left anterior descending (LAD) artery Left circumflex (LCX) artery Right coronary artery Marginal branch

13. Copyright © 2012 Wolters Kluwer Health | Lippincott Williams & Wilkins Blood Vessels of the Heart (cont’d) Collateral circulation –When two vessels that nourish the same area interconnect –In coronary obstruction, these vessels can enlarge to nourish endangered heart muscle. Ischemia: A reversible cell injury due to decreased blood and oxygen supply Myocardial infarction (MI): A localized area of dead tissue caused by a lack of blood supply

14. Copyright © 2012 Wolters Kluwer Health | Lippincott Williams & Wilkins Blood Vessels of the Heart (cont’d) Coronary Veins –Drain into capillaries in the myocardium, where delivery of oxygen and nutrients occurs, along with waste removal. Great cardiac vein Middle cardiac vein –These vessels transport blood into the coronary sinus, which returns blood to the right atrium.

15. Copyright © 2012 Wolters Kluwer Health | Lippincott Williams & Wilkins Systemic Blood Vessels Arteries –They carry blood away from the heart. Aorta is the largest artery. –Ascending aorta, aortic arch, thoracic aorta, and abdominal aorta. The smallest arteries are called arterioles. Capillaries –They make up most of the great length of the body’s blood vessels. They serve as “in-between” channels.

16. Copyright © 2012 Wolters Kluwer Health | Lippincott Williams & Wilkins Systemic Blood Vessels (cont’d) Veins and venules –They carry blood toward the heart. –The largest veins in the body are the superior vena cava (SVC) and inferior vena cava (IVC). –Venous blood return Venodilation Vasoconstriction

17. Copyright © 2012 Wolters Kluwer Health | Lippincott Williams & Wilkins Question Is the following statement true or false? The pulmonary veins carry deoxygenated blood.

18. Copyright © 2012 Wolters Kluwer Health | Lippincott Williams & Wilkins Answer False The pulmonary veins are the only veins that carry oxygenated blood. The pulmonary arteries are the only arteries in the body that carry deoxygenated blood.

19. Copyright © 2012 Wolters Kluwer Health | Lippincott Williams & Wilkins Tissue Layers Within Blood Vessels Tunica adventitia—the outermost layer –Composed of connective tissues, nerve cells, and nutrient capillaries; protects the outside of the vessel Tunica media—the middle layer –Contains the thickest elastic fibers, as well as connective tissue composed of polysaccharides; covered by a thick elastic band and smooth muscle fibers, which control the caliber of the vessel Tunica intima—the innermost layer –Thinnest layer held together by an intercellular matrix surrounded by connective tissue

20. Copyright © 2012 Wolters Kluwer Health | Lippincott Williams & Wilkins Cardiac Conduction

21. Copyright © 2012 Wolters Kluwer Health | Lippincott Williams & Wilkins Cardiac Conduction (cont’d) Conduction system of the heart –SA (sinoatrial) node (pacemaker) –AV (atrioventricular) node –Bundle of His (AV bundle) –Right and left bundle branches –Purkinje fibers to muscles of ventricles

22. Copyright © 2012 Wolters Kluwer Health | Lippincott Williams & Wilkins Cardiac Cycle Cardiac cycle or one heartbeat –In less than 1 second, both atria contract as both ventricles relax. Immediately after this, both ventricles contract as both atria relax. Systole: Sequence of dual contractions—the atria followed by the ventricles Diastole: Atrial relaxation, followed by ventricular relaxation One complete cardiac diastole –Ventricular diastole + atrial diastole

23. Copyright © 2012 Wolters Kluwer Health | Lippincott Williams & Wilkins Cardiac Cycle (cont’d) (S 1 ) –The first normal heart sound is called the “lub” and is produced by closure of the AV valves when the ventricles contract. (S 2 ) –The second normal heart sound is called the “dub” or “dup” and is produced by the closure of the aortic and pulmonary semilunar valves when the ventricles relax.

24. Copyright © 2012 Wolters Kluwer Health | Lippincott Williams & Wilkins Cardiac Cycle (cont’d) Abnormal heart sounds –Gallops, rubs, or murmurs Pulse –Rhythmic expansion of the arterial walls as the heart pumps blood to the body –Average of 72 beats per minute in an adult

25. Copyright © 2012 Wolters Kluwer Health | Lippincott Williams & Wilkins Cardiac Output Cardiac output (CO) –Amount of blood pumped by the ventricles in 1 minute Stroke volume (SV) –Volume of blood ejected with each heartbeat. Factors affecting CO –Body’s metabolic needs, autonomic nervous system’s influence on heart rate, effect of preload and afterload on SV, norepinephrine and epinephrine released by the sympathetic nervous system

26. Copyright © 2012 Wolters Kluwer Health | Lippincott Williams & Wilkins Blood Pressure Blood pressure –The force that blood exerts against the walls of blood vessels –Systolic blood pressure (sBP) –Diastolic blood pressure (dBP) Pulse pressure –Difference between systolic and diastolic pressure Average blood pressure in an adult is 120/80.

27. Copyright © 2012 Wolters Kluwer Health | Lippincott Williams & Wilkins Blood Pressure Regulation Factors other than the force and rate of the pumping heart that help to maintain or regulate blood pressure include –Amount and contents of circulating blood –Elasticity and ability of smooth muscles in arterial walls to dilate and constrict –Plaque build-up on arterial walls –Kidney functioning –Hormones

28. Copyright © 2012 Wolters Kluwer Health | Lippincott Williams & Wilkins Question Which of the following heart sounds are caused by the narrowing of a valve? a. Lub b. Dub c. Rub d. Murmur e. Gallop

29. Copyright © 2012 Wolters Kluwer Health | Lippincott Williams & Wilkins Answer d. Murmur Murmurs are most typically caused by narrowing (stenosis) of a valve or by blood regurgitating through a valve that does not close properly. Gallop sounds occur when ventricular filling creates audible vibrations during a normally silent diastolic phase. Rubs may be heard when layers of the pericardium rub together due to inflammation, as in pericarditis. Normal heart sounds are “lub” and “dub.”

30. Copyright © 2012 Wolters Kluwer Health | Lippincott Williams & Wilkins Effects of Aging Increased rigidity of vessels from decreased elasticity Dilation of blood vessels due to weakening muscle tone Fibrosis in the conduction system and heart Calcification of the valves Increased size of myocardium and atria Decreased cardiac output Decreased ability of cells to absorb oxygen Decreased sensitivity to stimuli

31. Copyright © 2012 Wolters Kluwer Health | Lippincott Williams & Wilkins Effects of Aging (cont’d) Blood vessel disorders can cause other problems such as –Downstream ischemia (insufficient blood supply) –Vessel damage or hemorrhage –Atherosclerosis –Vasculitis –Edema –Varicose veins or obstructed blood flow

32. Copyright © 2012 Wolters Kluwer Health | Lippincott Williams & Wilkins End of Presentation