Cardiovascular system presentation.bert

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Cardiovascular system presentation.bert

  1. 1. The Cardiovascular System  Blood  Heart  Blood vessels
  2. 2. 1 – 3. Functions of the blood 4. The normal pH range of the blood 5 – 6. The two components of the blood 7. The formation of blood cells takes place in the _______________. 8. The oxygen carrying pigment of RBC that gives its red color 9 – 12. Necessary elements for the production of RBC
  3. 3. 13 – 14. two general types of WBC 15 – 16. Two general phagocytic WBCs 17. contain HISTAMINE, HEPARIN and other active biochemical agents (released appropriately) 18 – 20. Three mechanisms in Hemostasis
  4. 4. - is an opaque, viscous fluid that can be classed as a tissue because of its complex structure and cellular components. - is a connective tissue composed of a liquid matrix called plasma that dissolves and suspends various cells and cell fragments
  5. 5. Functions of Blood 1. Transportation – blood transport oxygen from the lungs to the cells of the body and carbon dioxide from the cells to the lungs for exhalation; carries nutrients from the GI tract to body cells 2. Regulation - circulating blood helps maintain homeostasis in all body fluids 3. Protection – blood clotting mechanism, protection against diseases by phagocytosis
  6. 6. Physical Characteristics of Blood  Blood is denser and more viscous than water and feels slightly sticky  Its temperature is 38 degrees celsius  It has a slightly alkaline pH ranging from 7.35 – 7.45  It constitutes about 20% of extracellular fluid amounting to 8% of the total body mass  The blood volume is 5 – 6 liters ( average size adult male)
  7. 7. Components of Blood  Whole blood has two components: 1. Blood plasma – a watery liquid matrix that contains dissolved substances ( 55%) 2. Formed Elements – are cells and cell fragments ( red blood cells (RBC), white blood cells (WBC), platelets ) 45%
  8. 8. Components of the Blood
  9. 9. Formed elements of the Blood
  10. 10. Formation of Blood Cells  Hemopoiesis is the formation of blood cells from hemopoietic stem cells in red bone marrow  Myeloid stem cells form RBCs, platelets, granulocytes, monocytes; lymphoid stem cells give rise to lymphocytes  Several hemopoietic growth factors stimulate differentiation and proliferation of various blood cells
  11. 11. RED BLOOD CELLS (RBC)  Also called erythrocytes  It contain the oxygen – carrying protein ( hemoglobin) which is a pigment that gives whole blood its red color  Mature RBCs are biconcave discs that lack a nuclei and contain hemoglobin  The function of the hemoglobin in red blood cells is to transport oxygen and some carbon dioxide  RBCs live about 120 days
  12. 12.  After phagocytosis of aged RBCs by macrophages, hemoglobin is recycled  RBC formation ( erythropoiesis) occurs in adult red bone marrow of certain bones. It is stimulated by hypoxia, which stimulates release of erythropoietin by the kidneys
  13. 13. The Red blood cell
  14. 14. RBC Life cycle
  15. 15. WHITE BLOOD CELLS (WBC)  White blood cells are also called leucocytes  WBCs are nucleated cells  The two principal types are granulocytes ( neutrophils, eosinophils, and basophils) and agranulocytes ( lymphocytes and monocytes )  Its general function is to combat inflammation and infection. Neutrophils and macrophages ( evolved from monocytes) do so by phagocytosis
  16. 16.  Eosinophils combat the effects of histamine in allergic reaction, phagocytize antigen – antibody complexes and combat parasitic worms  Basophils liberate heparin, histamine and serotonin in allergic reactions that intensify the inflammatory response  B lymphocytes, in response to the presence of foreign substances called antigens, differentiate into plasma cells that produce antibodies. Antibodies attach to antigens and render them harmless providing immunity; T lymphocytes destroy foreign invaders directly
  17. 17. Types of White Blood Cells
  18. 18. the most numerous polymorphonuclear leukocytes/most numerous white blood cells, functions as phagocytes
  19. 19. phagocytes and function in allergic and other immune response.
  20. 20. contain HISTAMINE, HEPARIN and other active biochemical agents (released appropriately)
  21. 21. only white blood cells not produced in the bone marrow, arise from precursor cells in the marrow but develop to maturity in lymphoid tissues (spleen, thymus gland, tonsils, lymph nodes)
  22. 22. PLATELETS  Also called thrombocytes  Platelets are disc – shaped cell fragments that splinter from megakaryocytes  Platelets help stop blood loss from damaged blood vessels by forming a platelet plug. Their granules also contain chemicals that, once released, promote blood clotting  Platelets have a short lifespan normally 5 to 9 days  Aged and dead platelets are removed by macrophages in the spleen and liver
  23. 23. Hemostasis  Hemostasis refers to the stoppage of bleeding  It involves three mechanisms: - vascular spasm, platelet plug formation, and blood clotting ( coagulation) - In vascular spasm, the smooth muscle of the blood vessel wall contracts, which slow blood loss - Platelet plug formation involves the aggregation of platelets to stop bleeding
  24. 24. Blood Clotting  A clot is network of insoluble protein fibers ( fibrin) in which formed elements of blood are trapped  The chemicals involved in clotting are known as clotting ( coagulation) factors  Blood clotting involves a cascade of reactions that may be divided into three stages:(1) formation of prothrombinase,(2) conversion of prothrombin to thrombin, and(3) conversion of soluble fibrinogen into insoluble fibrin
  25. 25.  Clotting is initiated by the interplay of the extrinsic and intrinsic pathways of blood clotting  Normal coagulation requires Vitamin K and is followed by clot retraction ( tightening of the clot) and ultimately fibrinolysis ( dissolution of the clot)  Clotting in an unbroken blood vessel is called thrombosis. A thrombus that moves from its site of origin is called an embolus
  26. 26. Blood Groups and Blood Types  ABO and Rh blood groups are genetically determined and based on antigen – antibody responses  In an ABO group, the presence or absence of A and B antigens on the surface of RBCs determines the Blood type  In Rh system, individuals whose RBCs have Rh antigens are classified as Rh+; those who lack the antigen are Rh-
  27. 27. Development of Hemolytic Disease of the Newborn
  28. 28. Homeostatic Imbalances  Anemia – is a condition in which the oxygen – carrying capacity of blood is reduced - All of the many types of anemia are characterized by reduced number of RBCs or a decreased amount of hemoglobin in the blood Causes: - Inadequate absorption of Iron - Insufficient hemopoiesis - Excessive loss of RBCs - Increased destruction of RBCs - Deficient synthesis of hemoglobin - Destruction of red bone marrow
  29. 29. The Cardiovascular System: The Heart
  30. 30. Anatomy of the Heart  The heart is located in the mediastinum; about two – thirds of its mass is to the left of the midline mediastinum – a mass of tissue that extends from the sternum to the vertebral column between the lungs  The heart is shaped like a cone lying on its side; its apex is the pointed, inferior part, whereas its base is the broad, superior part  The heart acts as pump (pumping 2400 gallons ofThe heart acts as pump (pumping 2400 gallons of blood throughout the body every 24 hours) placedblood throughout the body every 24 hours) placed between and connecting the pulmonary andbetween and connecting the pulmonary and systemic circulation systemssystemic circulation systems
  31. 31. The Heart
  32. 32.  The pericardium is the membrane that surrounds and protects the heart; it consists of an outer fibrous layer and inner serous pericardium, which is composed of a parietal and a visceral layer  Between the parietal and visceral layers of the serous pericardium is the pericardial cavity that contains pericardial fluid that reduces friction between the two membranes
  33. 33. Layers of Heart Wall  Three layers make up the wall of the heart: 1. epicardium - visceral layer of the serous pericardium 2. myocardium – composed of cardiac muscle tissue 3. endocardium – consists of endothelium and connective tissue
  34. 34. Chambers of the Heart  The heart has four chambers: a. 2 superior chambers ( left and right atria ) b. 2 inferior chambers ( left and right ventricles)  Atria are the chambers that receive blood while the ventricles are the pumping chambers
  35. 35. Valves of the Heart  Atrioventricular valves Tricuspid valveTricuspid valve – between the right atrium and right– between the right atrium and right ventricle.ventricle. Mitral valveMitral valve – between the left atrium and left ventricle.– between the left atrium and left ventricle.  Semilunar valvesSemilunar valves Pulmonary valvePulmonary valve – between the right ventricle and– between the right ventricle and pulmonary arterypulmonary artery Aortic valveAortic valve – between the left ventricle and aorta.– between the left ventricle and aorta.
  36. 36. Cardiac Muscle Tissue  Cardiac muscle tissue usually contain a single centrally located nucleus  Compared to skeletal muscle tissue, cardiac muscle fibers have more and larger mitochondria, slightly smaller sarcoplasmic reticulum and wider transverse tubule  Cardiac muscle fibers are connected via end-to- end intercalated discs; desmosomes in the disc provide strength and gap junctions allow muscle action potentials to conduct from one muscle fiber to its neighbors
  37. 37. Autorhythmic Fibers: The Conducting System
  38. 38.  Autorhythmic fibers form the conducting system, cardiac muscle fibers that spontaneously depolarize and generate action potentials  Components of the conducting system are: a. sinoatrial node / (SA) node b. atrioventricular node / (AV) node c. atrioventricular bundle (AV) bundle/ bundle of His d. bundle branches e. Purkinje Fibers
  39. 39. Action Potential and Contraction of Contractile Fibers  The action potential is initiated by the SA node  It travels along the conducting system and spreads out to excite the “working” atrial and ventricular muscle fibers which are called contractile fibers  Action potential occurs as follows: 1. Depolarization 2. Plateau 3. Repolarization  Cardiac muscle tissue has long refractory period which prevents tetany
  40. 40. Electrocardiogram (ECG/EKG)  It is a composite record of action potentials produced by all the heart muscle fibers during each heartbeat  The instrument used to record the changes is an electrocardiograph  It determines if the conducting pathway is abnormal, if heart is enlarged and if certain regions of the heart are damaged
  41. 41.  A normal ECG consists of a P wave (atrial depolarization), a QRS complex ( onset of ventricular depolarization), and T wave ( ventricular repolarization)  PQ interval represents the conduction time from the beginning of atrial excitation to the beginning of ventricular excitation  The ST segment represents the time when ventricular contractile fibers are fully depolarized
  42. 42. The Cardiac Cycle  A cardiac cycle consists of the systole ( contraction) and diastole ( relaxation) of both atria, plus the systole and diastole of both ventricles  With an average heartbeat of 75 beats/min, a complete cardiac cycle requires 0.8 seconds  The phases of the cardiac cycle are: a. atrial systole b. ventricular systole c. relaxation period
  43. 43. Cardiac Output  Cardiac output ( CO) is the amount of blood ejected per minute by the left ventricle into the aorta ( or by the right ventricle into the pulmonary trunk)  It is calculated as follows: CO ( ml/min) = stroke volume in ml/beat X heart rate (HR) in beats/min Stroke volume is the amount of blood ejected by a ventricle during each systole
  44. 44.  Cardiac reserve is the difference between a person’s maximum cardiac output and his or her cardiac output at rest  Stroke volume is related to preload ( stretch on the heart before it contracts), contractility ( forcefulness of contraction), and afterload ( pressure that must be exceeded before ventricular ejection can begin)  According to the Frank – Starling law of the heart, a greater preload (end-diastolic volume) stretching cardiac muscle fibers just before they contract increases their force of contraction until the stretching becomes excessive
  45. 45. Regulation of Heart Rate  Nervous control of the cardiovascular system stems from the cardiovascular center in the medulla oblongata  Sympathetic impulses increase heart rate and force of contraction; parasympathetic impulses decrease heart rate  Heart rate is affected by hormones ( epinephrine, norepinephrine, thyroid hormones) ions (Na+, K+,Ca), age, gender, physical fitness, and body temperature
  46. 46. Homeostatic Imbalance  Coronary Artery Disease (CAD) - formation of atherosclerotic plaque in coronary arteries that reduces blood flow to the myocardium Risk factors:  High blood cholesterol  High blood pressure  Cigarette smoking  Obesity  Diabetes mellitus  Type A personality  Sedentary lifestyles
  47. 47.  Atherosclerosis begins when injury to the endothelium of an artery occurs that promotes aggregation of platelets and attracting phagocytes  At the injury site, cholesterol and triglycerides collect in the inner layer of the arterial wall  Contact with platelets, lipids and other components of the blood stimulates smooth muscle cells in the arterial wall to proliferate abnormally leading to enlargement of atherosclerotic plaque that obstruct blood flow  Plaque may provide a roughened surface that attracts platelets initiating clot formation and further obstructing blood flow
  48. 48. The Cardiovascular System: Blood Vessels and Hemodynamics
  49. 49. Structure and Function of Blood Vessels  Five main types of Blood vessels: - arteries, arterioles, capillaries, venules and veins  Arteries carry blood away from the heart to other organs - the wall of an artery consists of a tunica interna, a tunica media ( which maintains elasticity and contractility ) and a tunica externa - Large arteries are termed elastic ( conducting arteries) and medium – sized arteries are called muscular or (distributing ) arteries
  50. 50.  Many arteries anastomose: the distal end of two or more vessels unite. An alternate blood route from anastomosis is called collateral circulation. Arteries that do not anastomose are called end arteries  Arterioles are small arteries that deliver blood to capillaries - through constriction and dilation, arterioles assume a key role in regulating blood flow from arteries into capillaries and in altering arterial blood pressure
  51. 51.  Capillaries are microscopic blood vessels through which materials are exchanged between blood and tissue cells - capillaries branch to form an extensive network throughout a tissue. This network increases surface area, allowing a rapid exchange of large quantities of materials  Venules are small vessels that continue from capillaries and merge to form veins  Veins consists of the same three tunics as arteries but have thinner tunica interna and media - the lumen of a vein is also larger than that of a comparable artery
  52. 52.  Veins contain valves to prevent backflow of blood - weak valves can lead to varicose veins  Systemic veins are collectively called blood reservoir because they hold a large volume of blood - if this need arises, this blood can be shifted into other blood vessels through vasoconstriction of veins - the principal blood reservoir are the veins of the abdominal organs ( liver and spleen) and skin.
  53. 53. Capillary Exchange  The mission of the entire cardiovascular system is to keep blood flowing through capillaries to allow capillary exchange---the movement of substances between blood plasma and interstitial fluid  Substances enter and leave capillaries by: - diffusion, transcytosis, bulk flow ( filtration and reabsorption)
  54. 54. 1. Diffusion – most important method of capillary exchange - substances such as oxygen, carbon dioxide, glucose, amino acids and hormones - all plasma solutes except proteins pass easily across most capillary walls 2. Transcytosis – substances in blood plasma become enclosed in vesicle within tiny pinocytic vesicles that first enter the cell by endocytosis then move across the cell and exit on the other side by exocytosis
  55. 55. 3. Bulk Flow: Filtration and Reabsorption - is a passive process by which large numbers of ions, molecules, or particles in a fluid move together in the same direction - substances move in unison and they move at a rates far greater than can be accounted for by diffusion alone - bulk flow is important for the regulation of relative volume of blood and interstitial fluid Filtration – pressure – driven movement of fluid and solutes from blood capillaries into interstitial fluid Reabsorption – pressure-driven movement from interstitial fluid into blood capillaries
  56. 56.  The movement of water and solutes( except protein) through capillary walls depend on hydrostatic pressure and osmotic pressures  Overall, the volume of fluid and solutes reabsorbed normally is almost as large as the volume filtered ( Starling’s Law of the Capillaries)
  57. 57.  2 situations that may cause excess filtration: a. Increased capillary blood pressure b. Increased permeability of capillaries  1 situation that commonly causes inadequate reabsorption: a. decreased concentration of plasma proteins
  58. 58. Hemodynamics: Factors affecting Blood Flow  Blood flow is the volume of blood that flows through any tissue in a given time period ( in ml/min)  Cardiac output becomes distributed into circulatory routes that serves various body tissues depends on two more factors: (1) the pressure difference (2) the resistance to blood flow in specific blood vessels
  59. 59.  Blood flows from regions of higher pressure to lower pressure; the greater the pressure difference, the greater the blood flow  The higher the resistance, by contrast, the smaller the blood flow  The velocity of the blood is inversely related to the cross – sectional area of the blood vessels; blood flows slowest where cross – sectional area is greatest
  60. 60. Blood Pressure  Blood pressure is the pressure exerted on the walls of a blood vessel secondary to the contraction of the ventricles ( hydrostatic pressure) Systolic blood pressure - is the highest pressure attained in arteries during systole Diastolic blood pressure – the lowest arterial pressure during diastole  As blood leaves the aorta, its pressure falls progressively as the distance from the left ventricle increases
  61. 61. Resistance  Vascular Resistance – is the opposition to blood flow due to friction between blood and the walls of the blood vessels - It depends on three factors: a. size / diameter of the blood vessel lumen b. blood viscosity c. total blood vessel length
  62. 62.  Size of the lumen - The smaller the lumen of the blood vessel, the greater is the resistance to blood flow - As the arterioles dilate, resistance decreases and blood pressure falls - As the arterioles constrict, resistance increases and blood pressure rises  Blood Viscosity - The viscosity (thickness) of the blood depends mostly on the ratio of red blood cells to plasma volume and to smaller extent on the concentration of proteins in plasma  Total blood vessel length - The longer a blood vessel, the greater the resistance
  63. 63. Venous Return Venous Return – is the volume of blood flowing back to the heart through the systemic veins, occurs due to the pressure generated by contractions of the heart’s left ventricle - If pressure increases in the right atrium or ventricle, venous return will decrease and can lead to buildup of blood on the venous side of the systemic circulation
  64. 64. Velocity of Blood Flow  The velocity of blood flow is inversely related to the cross – sectional area of blood vessels; blood flows slowest where the cross – sectional area is greatest  The velocity of blood flow decreases from the aorta to arteries to capillaries and increases in venules and veins
  65. 65. Control of Blood Pressure and Blood Flow  The cardiovascular center is a group of neurons in the medulla oblongata that regulates heart rate, contractility, and blood vessel diameter  The cardiovascular center receives input from the higher brain regions and sensory receptors ( baroreceptors and chemoreceptors) - Baroreceptors monitor blood pressure and chemoreceptors monitor blood levels of oxygen, carbon dioxide and hydrogen ions
  66. 66. Hormonal Regulation of Blood Pressure 1. Renin – angiotensin – aldosterone (RAA) System 2. Epinephrine and norepinephrine 3. Antidiuretic Hormone ( ADH) 4. Atrial Natriuretic Peptide
  67. 67. Homeostatic Imbalances  Hypertension - persistently high blood pressure - a systolic blood pressure of 140 mmHg or greater and diastolic blood pressure of 90 mmHg or greater Classification: Stage 1: systolic of 140 – 159 mmHg; diastolic 90 - 99 mmHg Stage 2: systolic of 160 – 179 mmHg; diastolic 100 – 109 mmHg Stage 3: systolic of 180 mmHg or greater; diastolic of 110 mmHg or greater
  68. 68.  Types and Causes of Hypertension ( HPN) a. Primary Hypertension - 90 – 95% of all cases of HPN that cannot be attributed to any identifiable causes ( idiopathic and multifactorial ) b. Secondary Hypertension - 5 – 10% of the cases which has an identifiable underlying cause Several disorders causes secondary HPN: 1. Obstruction of renal blood flow 2. Hypersecretion of aldosterone ( tumor of the adrenal cortex) 3. Hypersecretion of epinephrine and norepinephrine ( pheochromocytoma )
  69. 69.  Damaging Effects of Untreated Hypertension - High blood pressure is known as the “ silent killer” because it can cause considerable damage to the blood vessels, heart, brain and kidneys before it causes pain or noticeable symptoms - In blood vessels, hypertension causes thickening of the tunica media, accelerates the development of atherosclerosis and coronary artery disease and increases systemic vascular resistance - In the heart, hypertension increases the afterload, which forces the ventricles to work harder to eject blood leading to myocardial hypertrophy that is accompanied by muscle damage and fibrosis
  70. 70. Lifestyle changes to reduce Hypertension  Lose weight  Limit alcohol intake  Exercise  Reduce intake of sodium ( salt)  Maintain recommended dietary intake of potassium, calcium and magnesium  Don’t Smoke  Manage Stress
  71. 71. End

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