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Cardiovascular system Anatomy and Physiology
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Chapter 15 1
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Chapter 15 Cardiovascular System
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Size of Heart Average Size of Heart 14 cm long 9 cm wide 3
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Location of Heart posterior to sternum medial to lungs
anterior to vertebral column base lies beneath 2nd rib apex at 5th intercostal space lies upon diaphragm 4
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Coverings of Heart 5
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Wall of the Heart 6
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Wall of the Heart 7
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Heart Chambers Right Atrium receives blood from Left Atrium
inferior vena cava superior vena cava coronary sinus Left Atrium receives blood from pulmonary veins Right Ventricle receives blood from right atrium Left Ventricle receives blood from left atrium 8
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Heart Valves 9
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Coronal Sections of Heart
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Heart Valves Tricuspid Valve Pulmonary and Aortic Valve 11
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Skeleton of Heart fibrous rings to which the heart valves are attached
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Path of Blood Through the Heart
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Path of Blood Through the Heart
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Blood Supply to Heart 15
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Blood Supply to Heart 16
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Angiogram of Coronary Arteries
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Heart Actions Atrial Diastole/Ventricular Systole
Atrial Systole/Ventricular Diastole Atrial Diastole/Ventricular Systole 18
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Cardiac Cycle Atrial Systole/Ventricular Diastole
blood flows passively into ventricles remaining 30% of blood pushed into ventricles A-V valves open/semilunar valves close ventricles relaxed ventricular pressure increases 19
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Cardiac Cycle Ventricular Systole/Atrial diastole
A-V valves close chordae tendinae prevent cusps of valves from bulging too far into atria atria relaxed blood flows into atria ventricular pressure increases and opens semilunar valves blood flows into pulmonary trunk and aorta 20
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Heart Sounds Lubb first heart sound occurs during ventricular systole
A-V valves closing Dupp second heart sound occurs during ventricular diastole pulmonary and aortic semilunar valves closing Murmur – abnormal heart sound 21
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Heart Sounds 22
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Cardiac Muscle Fibers Cardiac muscle fibers form a functional syncytium group of cells that function as a unit atrial syncytium ventricular syncytium 23
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Cardiac Conduction System
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Cardiac Conduction System
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Muscle Fibers in Ventricular Walls
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Electrocardiogram recording of electrical changes that occur in the myocardium used to assess heart’s ability to conduct impulses P wave – atrial depolarization QRS wave – ventricular depolarization T wave – ventricular repolarization 27
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Electrocardiogram 28
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Electrocardiogram A prolonged QRS complex may result from damage to the A-V bundle fibers 29
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Clinical Application Arrhythmias Ventricular fibrillation Tachycardia
rapid, uncoordinated depolarization of ventricles Tachycardia rapid heartbeat Atrial flutter rapid rate of atrial depolarization 30
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Cardiac Cycle 31
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Regulation of Cardiac Cycle
Autonomic nerve impulses alter the activities of the S-A and A-V nodes 32
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Regulation of Cardiac Cycle
Additional Factors that Influence HR physical exercise body temperature concentration of various ions potassium calcium parasympathetic impulses decrease heart action sympathetic impulses increase heart action cardiac center regulates autonomic impulses to the heart 33
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Blood Vessels arteries carry blood away from ventricles of heart
arterioles receive blood from arteries carry blood to capillaries capillaries sites of exchange of substances between blood and body cells venules receive blood from capillaries veins carry blood toward ventricle of heart 34
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Arteries and Arterioles
Artery thick strong wall endothelial lining middle layer of smooth muscle and elastic tissue outer layer of connective tissue carries blood under relatively high pressure Arterioles thinner wall than artery endothelial lining some smooth muscle tissue small amount of connective tissue helps control blood flow into a capillary 35
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Walls of Artery and Vein
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Arteriole smallest arterioles only have a few smooth muscle fibers
capillaries lack muscle fibers 37
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Metarteriole connects arteriole directly to venule 38
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Capillaries smallest diameter blood vessels
extensions of inner lining of arterioles walls are endothelium only semipermeable sinusoids – leaky capillaries 39
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Capillary Network 40
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Regulation of Capillary Blood Flow
Precapillary sphincters may close a capillary respond to needs of the cells low oxygen and nutrients cause sphincter to relax 41
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Exchange in the Capillaries
water and other substances leave capillaries because of net outward pressure at the capillaries’ arteriolar ends water enters capillaries’ venular ends because of a net inward pressure substances move in and out along the length of the capillaries according to their respective concentration gradients 42
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Venules and Veins Venule thinner wall than arteriole
less smooth muscle and elastic tissue than arteriole Vein thinner wall than artery three layers to wall but middle layer is poorly developed some have flaplike valves carries blood under relatively low pressure serves as blood reservoir 43
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Venous Valves 44
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Characteristics of Blood Vessels
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Blood Volumes in Vessels
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Arterial Blood Pressure
Blood Pressure – force the blood exerts against the inner walls of the blood vessels Arterial Blood Pressure rises when ventricles contract falls when ventricles relax systolic pressure – maximum pressure diastolic pressure – minimum pressure 47
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Pulse alternate expanding and recoiling of the arterial wall that can be felt 48
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Factors That Influence Arterial Blood Pressure
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Control of Blood Pressure
Controlling cardiac output and peripheral resistance regulates blood pressure 50
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Regulation of Cardiac Cycle
Autonomic nerve impulses alter the activities of the S-A and A-V nodes 51
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Control of Blood Pressure
If blood pressure rises, baroreceptors initiate the cardioinhibitory reflex, which lowers the blood pressure 52
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Control of Blood Pressure
Baroreceptors in the Vena Cava signal cardioaccelerator reflex and sends sympathetic impulses to the heart. Baroreceptors in Vena Cava stretched send signal to cardiac center sends sympathetic impulses to the heart Heart rate increases 53
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Control of Blood Pressure
Dilating arterioles helps regulate blood pressure (peripheral resistance) 54
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Venous Blood Flow not a direct result of heart action dependent on
skeletal muscle contraction breathing venoconstriction 55
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Central Venous Pressure
pressure in the right atrium factors that influence it alter flow of blood into the right atrium affects pressure within the peripheral veins weakly beating heart increases central venous pressure increase in central venous pressure causes blood to back up into peripheral vein 56
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Pulmonary Circuit consists of vessels that carry blood from the heart to the lungs and back to the heart 57
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Blood Flow Through Alveoli
cells of alveolar wall are tightly joined together the high osmotic pressure of the interstitial fluid draws water out of them 58
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Systemic Circuit composed of vessels that lead from the heart to all body parts (except the lungs) and back to the heart includes the aorta and its branches includes the system of veins that return blood to the right atrium 59
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Major Vessels of Arterial System
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Major Blood Vessels of the Heart
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Principal Branches of the Aorta
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Abdominal Aorta and Its Major Branches
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Cerebral Arterial Circle
Circle of Willis formed by anterior and posterior cerebral arteries, which join the internal carotid arteries 64
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Major Vessels of the Venous System
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Veins That Drain the Abdominal Viscera
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Veins from the Abdominal Viscera: Hepatic Portal Vein
Hepatic portal vein drains one set of capillaries and leads to another set 67
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Life-Span Changes cholesterol deposition in blood vessels
heart enlargement death of cardiac muscle cells increase in fibrous connective tissue of the heart increase in adipose tissue of the heart increase in blood pressure decrease in resting heart rate 68
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Clinical Application Arrhythmias Ventricular fibrillation Tachycardia
rapid, uncoordinated depolarization of ventricles Tachycardia rapid heartbeat Atrial flutter rapid rate of atrial depolarization 69
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