Chapter 12 The Circulatory System

1. Chapter 12The Circulatory System

2. HEART • Location, size, and position • Triangular organ • located in mediastinum • two thirds of the mass to the left of the body midline and one third to the right • the apex on the diaphragm • shape and size of a closed fist (Figure 12-1)

3. CPR • Cardiopulmonary resuscitation (CPR)— • the 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 • http://medicine.arizona.edu/spotlight/learn-sarver-heart-centers-continuous-chest-compression-cpr

5. HEART • Anatomy • Heart chambers (Figure 12-2) • Two upper chambers called atria (receiving chambers)—right and left atria • Two lower chambers called ventricles (discharging chambers)—right and left ventricles • Wall of each heart chamber is composed of cardiac muscle tissue called myocardium • Endocardium—smooth lining of heart chambers—inflammation of endocardium called endocarditis

6. Heart • Anatomy-con’t • Covering sac, or pericardium- • Pericardium is a two-layered fibrous sac with a lubricated space between the two layers • Inner layer called visceral pericardium or epicardium • Outer layer called parietal pericardium

8. HEART • Anatomy • Heart action • Contraction of the heart is called systole • Relaxation is called diastole

9. Heart valves (Figure 12-3) • Valves keep blood flowing through the heart and prevent backflow • Consist of two atrioventricular, or AV, and two semilunar (SL) valves • Tricuspid—at the opening of the right atrium into the ventricle • Bicuspid (mitral)—at the opening of the left atrium into the ventricle • Pulmonary semilunar—at the beginning of the pulmonary artery • Aortic semilunar—at the beginning of the aorta

10. BLOOD VESSELS • Types • Arteries—carry blood away from the heart • Veins—carry blood toward the heart • Capillaries—carry blood from the arterioles to the venules

11. BLOOD VESSELS • Structure (Figure 12-9) • Arteries • Tunica intima—inner layer of endothelial cells • Tunica media—smooth muscle with some elastic tissue, thick in arteries; important in blood pressure regulation • Tunica externa—thin layer of fibrous elastic connective tissue

12. Capillaries—microscopic vessels with only one layer—tunica intima • Veins • Tunica intima—inner layer; valves prevent retrograde movement of blood • Tunica media—smooth muscle; thin in veins • Tunica externa—heavy layer of fibrous connective tissue in many veins

14. BLOOD VESSELS • Functions • Arteries—distribution of nutrients, gases, etc., with movement of blood under high pressure; assist in maintaining the arterial blood pressure • Capillaries—serve as exchange vessels for nutrients, wastes, and fluids • Veins—collect blood for return to the heart; low pressure vessels

15. Names of main arteries—see Figure 12-10 and Table 12-1 • Names of main veins—see Figures 12-11 and 12-12 and Table 12-2

18. HEART • Blood supply to the heart muscle • Blood, which supplies oxygen and nutrients to the myocardium of the heart, flows through the right and left coronary arteries (Figure 12-5); called coronary circulation • Blockage of blood flow through the coronary arteries is called myocardial infarction (heart attack)

19. Angina pectoris—chest pain caused by inadequate oxygen to the heart • Coronary bypass surgery—veins from other parts of the body are used to bypass blockages in coronary arteries (Figure 12-6)

21. CIRCULATION • Systemic and pulmonary circulation Refers to the blood flow through the vessels arranged to form a circuit or circular pattern (Figure 12-13)

22. Pulmonary circulation • Carries blood to and from the lungs; arteries deliver deoxygenated blood to the lungs for gas exchange • Path goes from right ventricle through pulmonary arteries, lungs, pulmonary veins, to left atrium

23. Systemic circulation • Carries blood throughout the body • Path goes from left ventricle through aorta, smaller arteries, arterioles, capillaries, venules, venaecavae, to right atrium

25. HEART • Blood flow through the heart (Figure 12-4) • The heart acts as two separate pumps—the right atrium and ventricle performing different functions from the left atrium and ventricle

26. Pulmonary Circulation • venous blood enters the right atrium through the superior and inferior venae cavae • passes from the right atrium through • the tricuspid valve to the right ventricle; • from the right ventricle it passes through the pulmonary semilunar valve to the pulmonary artery to the lungs

27. Systemic Circulation • Blood moves from the lungs to the pulmonary veins into the left atrium, • passing through the bicuspid (mitral) valve to the 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

28. SSVC

29. CIRCULATION • Hepatic portal circulation (Figure 12-14) • Unique blood route through the liver • Vein (hepatic portal vein) exists between two capillary beds • Assists with homeostasis of blood glucose levels

31. CIRCULATION • Fetal circulation (Figure 12-15) • Refers to circulation before birth • Modifications required for fetus to efficiently secure oxygen and nutrients from the maternal blood • Unique structures include the placenta, umbilical arteries and vein, ductus venosus, ductus arteriosus, and foramen ovale

33. Next week • Unit 3 Seminar • Chapter 13 • The Lymphatic System and Immunity