Chapter 12


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Chapter 12

  1. 1. Chapter 12 Cardiovascular System
  2. 2. <ul><li>All but the simplest animals have circulatory systems with 3 main components: </li></ul><ul><ul><ul><li>A central pump </li></ul></ul></ul><ul><ul><ul><li>A vascular system </li></ul></ul></ul><ul><ul><ul><li>The circulating fluid </li></ul></ul></ul><ul><li>In the human cardiovascular system, </li></ul><ul><ul><li>The central pump is the heart . </li></ul></ul><ul><ul><li>The vascular system is the blood vessels. </li></ul></ul><ul><ul><li>The circulating fluid is the blood . </li></ul></ul>
  3. 3. 1. Blood Vessels
  4. 4. 1. Blood Vessels <ul><li>3 types: </li></ul><ul><ul><li>ARTERIES carry blood away from the heart. </li></ul></ul><ul><ul><li>VEINS carry blood toward the heart . </li></ul></ul><ul><ul><li>CAPILLARIES allow for exchange between the bloodstream and tissue cells . </li></ul></ul>
  5. 5. All blood vessels are lined by a thin layer of tightly packed epithelial cells . Structural differences in the walls of the different kinds of blood vessels correlate with their different functions.
  6. 6. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. arteriole venule b. Capillary valve a. Artery outer layer middle layer inner layer c. Vein <ul><li>3 layers to an arterial wall </li></ul><ul><li>Endothelium </li></ul><ul><li>Inner layer </li></ul><ul><li>simple squamous </li></ul><ul><li>epithelium </li></ul><ul><li>Middle layer </li></ul><ul><li>smooth muscle </li></ul><ul><li>Outer layer </li></ul><ul><li>connective tissue </li></ul><ul><li>Veins contain 3 </li></ul><ul><li>layers but less </li></ul><ul><li>smooth muscle </li></ul>
  7. 7. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. © Ed Reschke d. outer layer middle layer inner layer outer layer middle layer inner layer artery vein 20 µ m
  8. 8. THE CAPILLARIES <ul><li>Join arterioles to venules </li></ul><ul><li>Extremely narrow and only a single layer of endothelium thick </li></ul><ul><li>Form vast networks in all regions of the body </li></ul><ul><li>Very important role in homeostasis – exchange of substances </li></ul><ul><ul><li>Oxygen and nutrients </li></ul></ul><ul><ul><li>Wastes and carbon dioxide </li></ul></ul><ul><ul><li>Excess fluid picked up by lymphatic system </li></ul></ul>
  9. 9. Anatomy of a Capillary Bed blood flow arteriole capillaries arteriovenous shunt venule blood flow vein precapillary sphincters artery Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
  10. 10. Blood Flow Through Capillary Beds Notice how small the capillaries are, just wide enough for one red cell
  11. 11. The walls of capillaries are thin and leaky . <ul><li>As blood enters a capillary at the arterial end, blood pressure pushes fluid rich in oxygen, nutrients, and other substances into the interstitial fluid. </li></ul><ul><li>At the venous end of the capillary, CO 2 and other wastes diffuse from tissue cells and into the capillary bloodstream. </li></ul>
  12. 13. THE VEINS <ul><li>Walls are structured similarly to the walls of arteries (3 layers) </li></ul><ul><ul><li>Less smooth muscle and connective tissue in veins </li></ul></ul><ul><li>Often have valves to prevent the backflow of blood </li></ul><ul><ul><li>Varicose veins, hemorrhoids </li></ul></ul><ul><li>Great capacity to expand </li></ul><ul><ul><li>Serve as blood reservoir </li></ul></ul>
  13. 14. Varicoses <ul><li>Weak valves may be due to weak vein walls. </li></ul><ul><li>Weak walls </li></ul><ul><li>not so elastic </li></ul><ul><li>longer and wider walls </li></ul><ul><li>valves flaps separate </li></ul><ul><li>blood can flow backward through the valves </li></ul><ul><li>The backflow of blood fills the veins and stretches the walls even more </li></ul><ul><li>Bigger, swollen veins, often twisted as they try to squeeze into their normal space. </li></ul>
  14. 15. 2. the Heart
  15. 16. Pericardium : Sac around the heart <ul><li>Myocardium : </li></ul><ul><li>Major portion of the heart </li></ul><ul><ul><li>Consists mainly of cardiac muscle </li></ul></ul><ul><li>Endocardium: </li></ul><ul><ul><li>Lines the inner surface of the heart </li></ul></ul><ul><ul><li>Membrane consisting of connective tissue and endothelium </li></ul></ul>
  16. 17. <ul><li>The human heart is a muscular organ about the size of a fist. </li></ul><ul><ul><ul><li>It is located under the breastbone. </li></ul></ul></ul><ul><ul><ul><li>It has 4 chambers: </li></ul></ul></ul><ul><ul><ul><ul><li>Right atrium </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Left atrium </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Right ventricule </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Left ventricule </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Four Valves between chambers separate them, they are like “doors”. </li></ul></ul></ul></ul><ul><ul><ul><ul><li>The septum separates the left from the right side. </li></ul></ul></ul></ul>
  17. 18. septum semilunar valve left atrium right atrium atrio ventricular (bicuspid) valve atrio ventricular (tricuspid) vave chordae tendineae tendons right ventricle left ventricle
  18. 19. Blood arrives first in the atrium then goes to the ventricule. The valves prevent the blood to go back to the previous chamber
  19. 20. Path of Blood Through the Heart <ul><ul><li>Vena cava  right atrium  tricuspid valve  right ventricle  pulmonary semilunar valve  pulmonary trunk  pulmonary arteries  lungs  pulmonary veins  left atrium  bicuspid valve  left ventricle  aortic semilunar valve  aorta  body </li></ul></ul><ul><ul><li> </li></ul></ul>
  20. 21. <ul><li>The pulmonary circuit </li></ul><ul><li>carries blood between the heart and the lungs. </li></ul>
  21. 22. 2. The systemic circuit carries blood between the heart and the rest of the body.
  22. 23. Blood rich in CO 2 , vessels are blue Blood rich in O 2 , vessels are red
  23. 24. The Heartbeat (Cardiac Cycle) <ul><ul><li>Each time the heart beats: </li></ul></ul><ul><ul><ul><ul><li>The 2 atria contract simultaneously </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Then the 2 ventricles contract simultaneously </li></ul></ul></ul></ul><ul><ul><ul><ul><li>All the chambers then relax </li></ul></ul></ul></ul><ul><ul><li>Systole : Contraction of the heart muscle </li></ul></ul><ul><ul><li>Diastole : Relaxation of the heart muscle </li></ul></ul>
  24. 25. The Cardiac Cycle <ul><li>The heart relaxes and contracts regularly: </li></ul><ul><ul><li>Diastole is the relaxation phase of the heart cycle. </li></ul></ul><ul><ul><li>Systole is the contraction phase. </li></ul></ul>
  25. 26. The Heartbeat <ul><li>Heart Sounds described as </li></ul><ul><li>a “lub-dup” sound </li></ul><ul><li>“ Lub” sound: </li></ul><ul><li>atrioventricular valves closing </li></ul><ul><li>“ Dup” sound: </li></ul><ul><li>semilunar valves closing </li></ul><ul><li>A heart murmur (swishing sound) may be due to a leaky valve </li></ul><ul><li> </li></ul>
  26. 27. The Pacemaker and the Control of Heart Rate The pacemaker sets the tempo of the heartbeat . It is composed of specialized muscle tissue in the wall of the right atrium.
  27. 28. The impulses sent by the pacemaker produce electrical currents that can be detected by electrodes placed on the skin. These are recorded in an electrocardiogram (ECG or EKG). An artificial pacemaker: is a medical device which uses electrical impulses, delivered by electrodes contracting the heart muscles, to regulate the beating of the heart.
  28. 29. Electrocardiogram (ECG) <ul><li>A recording of the electrical changes occurring in the heart </li></ul>Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. b. R P T Q S <ul><li>P Wave occurs just prior to atrial contraction </li></ul><ul><li>QRS complex occurs just prior to ventricular contraction </li></ul><ul><li>T wave occurs after ventricular contraction </li></ul>
  29. 30. Blood pressure <ul><li>Systolic Pressure results from the contraction of the ventricule </li></ul><ul><li>Diastolic Pressure is the pressure in the arteries when the heart relaxes </li></ul><ul><li>As blood flows from the aorta into the arteries and arterioles, blood pressure falls </li></ul><ul><li>Also, the difference between systolic and diastolic pressure gradually diminishes </li></ul><ul><li>In the capillaries, blood flow is slow and fairly even </li></ul>
  30. 31. <ul><ul><li>Blood pressure is expressed in millimeters of mercury (mmHg) </li></ul></ul><ul><li>Optimal blood pressure for adults is <120 systolic and < 80 diastolic. </li></ul><ul><li>High blood pressure or hypertension is: </li></ul><ul><li>persistent systolic blood pressure  140 </li></ul><ul><li>and/or diastolic blood pressure  90. </li></ul>
  31. 32. Blood Return Through Veins After chemicals are exchanged between the blood and body cells, blood returns to the heart via the veins . <ul><li>By the time blood enters the veins, the pressure from the heart has dropped to near zero but blood still moves through the veins against the force of gravity. </li></ul><ul><li>As skeletal muscles contract, they help squeeze the blood along. </li></ul><ul><ul><li>Valves prevent backflow </li></ul></ul>
  32. 33. 4. BLOOD
  33. 34. 4. Blood <ul><li>Contains: </li></ul><ul><li>Plasma (1/2 of this volume) liquid </li></ul><ul><li>Different types of cellular components: </li></ul><ul><ul><li>Red blood cells </li></ul></ul><ul><ul><li>White blood cells </li></ul></ul><ul><ul><li>Platelets </li></ul></ul>
  34. 35. BLOOD FUNCTIONS <ul><ul><li>Transport functions </li></ul></ul><ul><ul><li>Regulatory functions </li></ul></ul><ul><ul><li>Protective functions </li></ul></ul>c. neutrophils platelets monocyte eosinophil lymphocyte basophil 250  red blood cell Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. © EdReschke
  35. 36. A. Red Blood Cells and Oxygen Transport <ul><li>most numerous type of blood cell. </li></ul><ul><li>also called erythrocytes . </li></ul><ul><li>Manufactured in red bone marrow </li></ul><ul><li>When mature lack a nucleus </li></ul><ul><li>Hemoglobin: </li></ul><ul><li>Large amount are contained in each red blood cell. </li></ul><ul><li>contains iron and transports oxygen throughout the body. </li></ul>
  36. 37. capillary a. Blood capillary 400  b. Red blood cells SEM 4,175  helical shape of the polypeptide molecule heme group iron c. Hemoglobin molecule Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. a: © Ed Reschke/Peter Arnold; b: © Andrew Syred/Photo Researchers, Inc. <ul><li>Contain hemoglobin </li></ul><ul><ul><li>Red iron-containing pigment </li></ul></ul><ul><ul><li>Heme portion binds oxygen </li></ul></ul><ul><ul><li>Carbon monoxide can also bind at heme sites </li></ul></ul><ul><ul><ul><li>Combines more readily than oxygen </li></ul></ul></ul><ul><ul><ul><li>Can be lethal </li></ul></ul></ul>
  37. 38. <ul><li>Red Blood Cells </li></ul><ul><ul><li>Last around 120 days </li></ul></ul><ul><ul><li>Destroyed in the liver and spleen </li></ul></ul><ul><ul><ul><li>Iron is mostly recycled </li></ul></ul></ul><ul><ul><ul><li>Heme portion degraded – bile pigments </li></ul></ul></ul><ul><ul><li>Carbohydrates at the surface will determine blood type </li></ul></ul>
  38. 39. BLOOD TYPE
  39. 40. Anemia <ul><li>Too few red blood cells </li></ul><ul><li>Not enough hemoglobin in red blood cells </li></ul><ul><li>3 causes </li></ul><ul><ul><li>Decreased production of red blood cells </li></ul></ul><ul><ul><ul><li>Iron-deficiency anemia </li></ul></ul></ul><ul><ul><li>Loss of red blood cells </li></ul></ul><ul><ul><li>Destruction of red blood cells </li></ul></ul>
  40. 41. B. White Blood Cells and Defense <ul><li>fight infections and cancer. </li></ul><ul><li>also called leukocytes . </li></ul><ul><li>Larger than red blood cells </li></ul><ul><li>Nucleated </li></ul>
  41. 42. White Blood Cells <ul><li>Granular leukocytes have visible granules in cytoplasm (enzymes and proteins) </li></ul><ul><ul><li>Neutrophils : most abundant leukocyte, phagocytic </li></ul></ul><ul><ul><li>Basophils: granules stain deep blue and release histamine </li></ul></ul><ul><ul><li>Eosinophils : stain deep red, fight parasitic worms </li></ul></ul><ul><li>Agranular leukocytes lack visible granules </li></ul><ul><ul><li>Lymphocytes-T and B cells , roles in immunity </li></ul></ul><ul><ul><li>Monocytes -largest WBC ’s, phagocytic dendritic cells and macrophages </li></ul></ul>
  42. 43. C. Platelets and Blood Clotting <ul><li>Blood contains 2 components that aid in clotting: </li></ul><ul><ul><li>Platelets (thrombocytes) are bits of cytoplasm pinched off from larger cells in the bone marrow. </li></ul></ul><ul><ul><li>Fibrinogen is a membrane-wrapped protein found in plasma. </li></ul></ul>
  43. 44. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Fibrinogen Ca2 + 1. Blood vessel is punctured. 2. Platelets congregate and form a plug. 3. Platelets and damaged tissue cells release prothrombin activator, which initiates a cascade of enzymatic reactions. 4. Fibrin threads form and trap red blood cells. Blood-clotting process Prothrombin activator Prothrombin Thrombin Fibrin threads Ca2 +
  44. 45. Platelets release molecules that convert fibrinogen into fibrin. <ul><li>Fibrin is a threadlike protein. </li></ul><ul><li>Fibrin forms a dense network to create a patch. </li></ul>
  45. 46. Hemophilia <ul><li>Inherited disorder </li></ul><ul><ul><li>Most common type has faulty gene on X chromosome </li></ul></ul><ul><li>Deficiency in a clotting factor </li></ul><ul><li>Internal bleeding can cause serious damage to cells and tissues </li></ul><ul><li>Hemophilia is treated by blood transfusions and injections of clotting factors </li></ul>
  46. 47. 6.The Role of the Cardiovascular System in Homeostasis
  47. 48. 5.The Role of the Cardiovascular System in Homeostasis <ul><li>The cardiovascular system performs several homeostatic functions: </li></ul><ul><ul><ul><li>Controlling chemical balance </li></ul></ul></ul><ul><ul><ul><li>Controlling the composition of the blood </li></ul></ul></ul><ul><ul><ul><li>Regulating body temperature </li></ul></ul></ul><ul><ul><ul><li>Distributing hormones </li></ul></ul></ul><ul><ul><ul><li>Defending against foreign invaders </li></ul></ul></ul>
  48. 49. What happens when this homeostasis is not maintained? Cardiovascular Disease Cardiovascular disease accounts for 40% of all deaths in the United States. The leading cause of death in the United States is heart attack.
  49. 50. <ul><li>chronic cardiovascular disease (lasts for a long time or recurrent). </li></ul><ul><li>The blood vessels become impaired gradually. </li></ul><ul><li>Vessels are narrowed by plaques of cholesterol and other substances. This fatty material thickens, hardens, and may eventually block the arteries. </li></ul><ul><li>The tissue will not be supplied with blood and will die. </li></ul>A. Atherosclerosis Cause of strokes, heart attack.
  50. 51. fat coronary artery ulceration lumen of vessel cholesterol crystals atherosclerotic plaque Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. © Biophoto Associates/Photo Researchers, Inc.
  51. 52. B. Heart Valve Disease <ul><ul><li>90,000 people/year have faulty heart valves repaired or replaced </li></ul></ul><ul><ul><li>May be malformed at birth </li></ul></ul><ul><ul><li>More commonly degenerate due to age or disease </li></ul></ul><ul><ul><li>A narrowing of the aorta is the </li></ul></ul><ul><ul><li>most common cause, it results in </li></ul></ul><ul><ul><li>the bicuspid valve to prolapse or </li></ul></ul><ul><ul><li>“ fall” into the ventricule. </li></ul></ul>
  52. 53. C. STROKE <ul><li>Cerebrovascular accident </li></ul><ul><li>Arteriole in the brain bursts or is blocked by an embolus </li></ul><ul><li>Lack of oxygen to brain can cause paralysis or death </li></ul><ul><li>Warning signs: numbness in hands or face, difficulty speaking, temporary blindness in one eye </li></ul>
  53. 54. D. HEART ATTACK When blood exits the heart, several coronary arteries immediately branch off to supply the heart muscle. If 1 or more of these arteries is blocked, the heart muscle cells will quickly die.
  54. 55. Coronary Bypass Operations <ul><li>Bypass blocked areas of coronary arteries </li></ul><ul><li>Can graft another vessel to the aorta and then to the blocked coronary artery past the point of blockage </li></ul><ul><li>Gene therapy may be a future treatment </li></ul>
  55. 56. <ul><li>Angioplasty </li></ul><ul><ul><li>Catheter is placed in clogged artery </li></ul></ul><ul><ul><li>Balloon attached to catheter is inflated </li></ul></ul><ul><ul><li>Increases the lumen of the vessel </li></ul></ul><ul><ul><li>Stents can be placed to keep vessel open </li></ul></ul>Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. stent catheter a. Artery is closed. b. Stent is placed. c. Balloon is inflated. arterial wall
  56. 57. Heart Transplants <ul><ul><li>Transplants usually successful but shortage of donors </li></ul></ul><ul><ul><li>LVAD-left ventricular assist device </li></ul></ul><ul><ul><ul><li>Temporary alternative to heart transplant </li></ul></ul></ul><ul><ul><ul><li>Tube passes blood from left ventricle to the LVAD </li></ul></ul></ul><ul><ul><ul><li>Blood is pumped to the aorta </li></ul></ul></ul>
  57. 58. TAH-total artificial heart <ul><ul><li>Generally only used on very ill patients </li></ul></ul><ul><ul><li>Survival rates are not good but may be because patients are so ill </li></ul></ul>
  58. 59. Hypertension (high blood pressure) <ul><ul><li>Affects about 20% of all Americans </li></ul></ul><ul><ul><li>Usually caused by a narrowing of the arteries, which means the blood pressure needs to be higher to get the blood through </li></ul></ul><ul><ul><li>Age, gender, and lifestyle can influence blood pressure </li></ul></ul><ul><ul><ul><li>Obesity </li></ul></ul></ul><ul><ul><ul><li>Smoking </li></ul></ul></ul><ul><ul><ul><li>High dietary salt intake </li></ul></ul></ul><ul><ul><li>Medications can be used to treat this disease </li></ul></ul>
  59. 60. <ul><li>How can you avoid becoming a heart disease victim? </li></ul><ul><ul><li>Don ’t smoke. </li></ul></ul><ul><ul><ul><li> O 2 to the heart and to other tissues </li></ul></ul></ul><ul><ul><ul><li> exercise tolerance. </li></ul></ul></ul><ul><ul><ul><li> HDL (good) cholesterol. </li></ul></ul></ul><ul><ul><ul><li> blood pressure and heart rate </li></ul></ul></ul><ul><ul><li>Exercise. </li></ul></ul><ul><ul><li>Eat a heart-healthy diet. </li></ul></ul>