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Unit 2

Unit 2. Introduction and Questions Review of Circulatory System Playing for Kudos. Chapter 12 The Circulatory System. HEART. Location, size, and position

wesley-doyle
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Unit 2

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  1. Unit 2 Introduction and Questions Review of Circulatory System Playing for Kudos

  2. Chapter 12The Circulatory System

  3. HEART • Location, size, and position • 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 on the diaphragm; shape and size of a closed fist (Figure 12-1) • 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; if combined with artificial respiration procedure, it can be life saving

  4. HEART • Anatomy • Heart chambers (Figure 12-2) • Two upper chambers • Two lower chambers • Wall of each heart chamber is composed of cardiac muscle tissue called myocardium • Endocardium—smooth lining of heart chambers—inflammation of endocardium called endocarditis • Covering sac, or pericardium • Pericardium is a two-layered fibrous sac with a lubricated space between the two layers • Inner layer called • Outer layer called

  5. HEART • Anatomy • Heart action • Contraction of the heart • Relaxation is called • 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

  6. HEART • Heart sounds • Two distinct heart sounds in every heartbeat or cycle—“lub-dub” • First sound (lub) -the vibration and closure of AV valves during contraction of the ventricles • Second sound (dub) -the closure of the semilunar valves during relaxation of the ventricles

  7. 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 • Sequence of blood flow: 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 • blood moves from the lungs to 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

  8. HEART • Blood supply to the heart muscle • coronary circulation • myocardial infarction (heart attack) • Angina pectoris • Coronary bypass surgery

  9. HEART • Conduction system of the heart (Figure 12-7) • Intercalated disks are electrical connectors • SA (sinoatrial) node, the • AV (atrioventricular) • AV bundle (bundle of His • Purkinje fibers

  10. HEART • Electrocardiogram (Figure 12-8) • Specialized conduction system structures generate and transmit the electrical impulses that result in contraction of the heart • These tiny electrical impulses 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 • 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

  11. 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

  12. 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 • 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

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