Y khoa, dược - The cardiovascular system

23The Cardiovascular System23-2Learning Outcomes23.1 Describe the structure of the heart and the function of each part.23.2 Trace the flow of blood through the heart.23.3 List the most common heart sounds and what events produce them.23.4 Explain how heart rate is controlled by the electrical conduction system of the heart. 23-3Learning Outcomes (cont.)23.5 List the different types of blood vessels and describe the functions of each.23.6 Define blood pressure and tell how it is controlled.23.7 Trace the flow of blood through the pulmonary and systemic circulation.23.8 List the major arteries and veins of the body and describe their locations. 23-4Learning Outcomes (cont.)23.9 List and describe the components of blood.23.10 Give the functions of red blood cells, the different types of white blood cells, and platelets.23.11 List the substances normally found in plasma.23.12 Explain how bleeding is controlled. 23.13 Explain the differences among blood types A, B, AB, and O.23-5Learning Outcomes (cont.)23.14 Explain the difference between Rh-positive blood and Rh-negative blood.23.15 Explain the importance of blood typing and tell which blood types are compatible.23.16 Describe the causes, signs and symptoms, and treatments of various diseases and disorders of the cardiovascular system. 23-6Introduction The cardiovascular system consists of heart and blood vesselsSends blood toLungs for oxygenDigestive system for nutrientsAlso circulates waste products to certain organ systems for removal from the blood23-7Structures of the HeartCone-shaped organ about the size of a loose fist In the mediastinum Extends from the level of the second rib to about the level of the sixth ribSlightly left of the midline23-8Structures of the Heart (cont.) Heart is bordered:Laterally by the lungsPosteriorly by the vertebral columnAnteriorly by the sternumRests on the diaphragm inferiorly23-9Structures of the Heart (cont.)Heart coveringsPericardium Covers the heart and large blood vessels attached to the heartVisceral pericardium Innermost layerDirectly on the heartParietal pericardium Layer on top of the visceral pericardium Heart walls:Epicardium Outermost layerFat to cushion heartMyocardium Middle layer Primarily cardiac muscleEndocardium Innermost layerThin and smoothStretches as the heart pumpsClick for Larger View23-10Back23-11Structures of the Heart (cont.)Four chambersTwo atriaUpper chambersLeft and rightSeparated by interatrial septumTwo ventriclesLower chambersLeft and rightSeparated by interventricular septumClick for View of Heart Atrioventricular septum separates the atria  from the ventricles23-12Structures of the Heart (cont.)Tricuspid valve – prevents blood from flowing back into the right atrium when the right ventricle contractsBicuspid (mitral) valve – prevents blood from flowing back into the left atrium when the left ventricle contracts Pulmonary semilunar valve – prevents blood from flowing back into the right ventricle Aortic semilunar valve – prevents blood from flowing back into the left ventricle Click for View of Heart23-13The Heart LabeledBack23-14Blood Flow Through the HeartDeoxygenated blood in from bodyOxygenated blood in lungsAtria ContractVentricles ContractDeoxygenated blood out to lungsOxygenated blood out to body23-15Blood Flow Through the Heart (cont.)Right AtriumRight VentriclePulmonarySemilunarValveLeft AtriumBicuspidValveLeft VentriclePulmonaryValveTricuspidValveLungsBodyAorticSemilunarValve23-16Cardiac CycleRight atrium contractsTricuspid valve opens Blood fills right ventricleRight ventricle contractsTricuspid valve closesPulmonary semilunar valve opensBlood flows into pulmonary arteryLeft atrium contracts Bicuspid valve opens Blood fills left ventricleLeft ventricle contractsBicuspid valve closesAortic semilunar valve opensBlood pushed into aortaOne heartbeat = one cardiac cycleAtria contract and relaxVentricles contract and relax23-17Cardiac Cycle (cont.)Influenced byExerciseParasympathetic nervesSympathetic nervesCardiac control centerBody temperaturePotassium ionsCalcium ions23-18Heart SoundsOne cardiac cycle – two heart sounds (lubb and dubb) when valves in the heart snap shutLubb – first soundWhen the ventricles contract, the tricuspid and bicuspid valves snap shut Dubb – second sound When the atria contract and the pulmonary and aortic valves snap shut 23-19Cardiac Conduction SystemGroup of structures that send electrical impulses through the heartSinoatrial node (SA node)Wall of right atriumGenerates impulseNatural pacemakerSends impulse to AV nodeAtrioventricular node (AV node)Between atria just above ventriclesAtria contractSends impulse to the bundle of HisBundle of HisBetween ventriclesTwo branches Sends impulse to Purkinje fibersPurkinje fibersLateral walls of ventriclesVentricles contractClick the i below for a Diagram23-20Cardiac Conduction SystemBack23-21Apply Your KnowledgeGood Job!Match the following:__ Tricuspid valve A. Two branches; sends impulse to Purkinje  fibers__ Bicuspid valve B. Covering of the heart and aorta__ Pericardium C. Between the right atrium and the right  ventricle __ SA node D. In the lateral walls of ventricles__ Bundle of His E. Natural pacemaker__ Purkinje fibers F. Between the left atrium and the left ventricle DAEBFCANSWER:23-22Blood VesselsClosed pathway that carries blood from the heart to cells and back to the heartTypesArteriesArteriolesVeinsVenulesCapillaries 23-23Arteries and Arterioles Strongest of the blood vesselsCarry blood away from the heartUnder high pressureVasoconstrictionVasodilation ArteriolesSmall branches of arteriesAortaTakes blood from the heart to the bodyCoronary arteriesSupply blood to heart muscle23-24Veins and Venules Blood under no pressure in veinsDoes not move very easilySkeletal muscle contractions help move bloodSympathetic nervous system also influences pressureValves prevent backflow Venules Small vessels formed when capillaries mergeSuperior and inferior vena cavaLargest veinsCarry blood into right atrium23-25CapillariesBranches of arteriolesSmallest type of blood vesselConnect arterioles to venulesOnly about one cell layer thickOxygen and nutrients can pass out of a capillary into a body cell Carbon dioxide and other waste products pass out of a body cell into a capillary 23-26Apply Your KnowledgeHow do arteries control blood pressure?ANSWER: The muscular walls of arteries can constrict to increase blood pressure or dilate to decrease blood pressure.Correct!23-27Blood PressureForce blood exerts on the inner walls of blood vesselsHighest in arteries Lowest in veins Systolic pressure Ventricles contractBlood pressure in arteries is at its greatestDiastolic pressure Ventricles relaxBlood pressure in arteries is at its lowestReported as the systolic number over the diastolic number 23-28Blood Pressure (cont.)Control is based mainly on the amount of blood pumped out of the heartThe amount of blood entering should equal the amount pumped from the heartStarling's law of the heart Blood entering the left ventricle stretches the wall of the ventricleThe more the wall is stretchedThe harder it will contract and The more blood it will pump out23-29Blood Pressure (cont.)Baroreceptors Also help regulate blood pressureLocated in the aorta and carotid arteriesHigh blood pressure in aorta  message to cardiac center in brain  decreases heart rate  lowers blood pressureLow blood pressure in aorta  message to cardiac center in the brain  increases heart rate  increases blood pressure23-30Apply Your KnowledgeWhat is the difference between the systolic pressure and diastolic pressure?ANSWER: Systolic pressure is the result of the contraction of the ventricles increasing the pressure in the arteries. Diastolic pressure is the result of the relaxation of the ventricles lowering the pressure in the arteries.Good Answer!23-31CirculationPulmonary circuit right atrium  right ventricle  pulmonary artery trunk  pulmonary arteries  lungs  pulmonary veins  heart (left atrium) Systemic circuitleft atrium  left ventricle  aorta  arteries  arterioles  capillaries  venules  veins  vena cava  heart (right atrium)23-32Circulation (cont.)Arterial systemCarries oxygen-rich blood away from the heartPulmonary arteries carry oxygen-poor bloodPaired – left and right artery of the same name 23-33Circulation (cont.)Venous systemCarries oxygen-poor blood toward the heartExcept pulmonary veinsMost large veins have the same names as the arteries they are next to Hepatic portal systemCollection of veins carrying blood to the liver Click for Larger View23-3423-35Apply Your KnowledgeARTERIES: Pulmonary arteries carry oxygen-poor blood. Do pulmonary arteries carry blood with high levels of oxygen or low levels of oxygen?YIPPEE!23-36Blood A type of connective  tissueRed blood cells (erythrocytes) White blood cells (leukocytes) Platelets – cell fragments Plasma – fluid part of bloodAverage-sized adult has 4 to 6 liters of blood Amount depends on:Size of personAmount of adipose tissueConcentrations of ionsFemales have less than males23-37Blood ComponentsHematocrit The percentage of red blood cellsNormal is about 45%White cells and platelets = 1%Plasma = 55%© Cre8tive StudiosAlamy RF23-38Red Blood CellsErythrocytes Transport oxygen throughout the bodySmall biconcave-shaped cells Hemoglobin is a pigment in RBCsOxyhemoglobin carries oxygen; bright red Deoxyhemoglobin does not carry oxygen; darker red Carries carbon dioxide, so also called carboxyhemoglobinAnemia – low RBC countErythropoietin – regulates production of RBCs23-39Red Blood Cells (cont.)© Cre8tive StudiosAlamy RF23-40White Blood Cells GranulocytesNeutrophils (55%) –destroy bacteria, viruses, and toxins in the bloodstream (phagocytes)Eosinophils (3%) – get rid of parasitic infections such as worm infectionsBasophils (1%) – control inflammation and allergic reactions AgranulocytesMonocytes (8%) – destroy bacteria, viruses, and toxins in blood Lymphocytes (33%) – provide immunity for the body 23-41White Blood Cells (cont.)WBC count normally 5000 to 10,000 cells per cubic millimeter of bloodLeukocytosis Elevated WBC countUsually due to infectionLeukopenia Low WBC countSome viral infections and other conditions23-42PlateletsFragments of cells found in the bloodstreamAlso called thrombocytes Important in the clotting process of bloodNormal count130,000 to 360,000 platelets per cubic millimeter of blood   23-43PlasmaLiquid portion of blood composed mostly of waterProteinsAlbumins Smallest plasma proteinsPull water in to help maintain blood pressureGlobulins – transport lipids and fat-soluble vitaminsFibrinogen – needed for blood clottingNutrientsAmino acidsGlucoseNucleotidesLipids from the digestive tractGases – oxygen, carbon dioxide, and nitrogenElectrolytesWaste products23-44Bleeding ControlHemostasis – the control of bleedingThree processes of hemostasisBlood vessel spasmPlatelet plug formationBlood coagulation23-45Platelet plug formation:23-46Blood TypesTypes are distinguished by antigens and antibodiesAgglutinationClumping of red blood cells Antigens on surface of RBCs bind to antibodies in plasma23-47Blood Types (cont.)Blood TypeAntigen PresentAntibody PresentBlood That Can Be ReceivedAABA and OBBAB and OABABNoneA, B, AB, and O ONoneA and BO23-48Blood Types (cont.)Rh antigen – protein on RBCsRh-positiveRBCs contain the Rh antigenRh-negative RBCs do not contain the Rh antigen Rh-positive blood is given to Rh-negative personAntibodies formIf Rh-negative person receives more Rh-positive bloodAntibodies bind to the donor cells Agglutination occurs23-49Apply Your KnowledgeTrue or False:__ Hematocrit is the percentage of WBCs in the blood.__ Neutrophils destroy bacteria, viruses, and toxins in the  bloodstream. __ Platelets are important to the clotting process.__ Albumin is a small plasma protein that pushes water out of the  bloodstream.__ Hemostasis is the control of bleeding.__ A person with type AB blood can only receive type AB blood.__ Blood should be matched for Rh factor.pulls water intoRBCsreceive any type of bloodTTFTFTFANSWER:Truly Terrific!23-50Chest PainCardiacMyocardial infarctionAnginaPericarditisCoronary spasmNon-cardiacHeartburnPanic attacksPleurisyCostochondritis Pulmonary embolismSore musclesBroken ribsTake all complaints of chest pain seriously!23-51Chest Pain (cont.)Determine causeElectrocardiogramStress testsBlood testsChest x-rayNuclear scanCoronary catheterizationEchocardiogram Endoscopy 23-52Diseases and Disorders of the Cardiovascular SystemDiseaseDescriptionAnemiaThe blood does not have enough red blood cells or hemoglobin to carry an adequate amount of oxygen to the body’s cells Aneurysm A ballooned, weakened arterial wall ArrhythmiasAbnormal heart rhythmsCarditisInflammation of the heartEndocarditisInflammation of the innermost lining of the heart, including valves23-53Diseases and Disorders of the Cardiovascular System (cont.)DiseaseDescriptionMyocarditisInflammation of the muscular layer of the heartPericarditisInflammation of the membranes that surround the heart (pericardium)Congestive heart failureWeakening of the heart over time; heart is unable to pump enough blood to meet body’s needsCoronary artery disease (CAD)Atherosclerosis; narrowing of coronary arteries caused by hardening of the fatty plaque deposits within the arteries 23-54Diseases and Disorders of the Cardiovascular System (cont.)DiseaseDescriptionHypertensionHigh blood pressure; consistent resting blood pressure equal to or greater than 140/90 mm HgLeukemiaBone marrow produces a large number of abnormal WBCsMurmurs Abnormal heart soundsMyocardial infarctionHeart attack; damage to cardiac muscle due to a lack of blood supply23-55Diseases and Disorders of the Cardiovascular System (cont.)DiseaseDescriptionSickle cell anemiaAbnormal hemoglobin causes RBCs to change to a sickle shape; abnormal cells stick in capillariesThalassemiaInherited form of anemia; defective hemoglobin chain causes, small, pale, and short-lived RBCsThrombophlebitisBlood clots and inflammation develop in a veinVaricose veinsTwisted, dilated veins 23-56Apply Your KnowledgeANSWER: Anemia is a condition in which a person does not have enough red blood cells or hemoglobin in the blood to carry an adequate amount of oxygen to body cells. The doctor has told your patient she has anemia. How would you explain this to her?Bravo!23-57In Summary23.1 The structures of the heart include the pericardium, epicardium, myocardium, and endocardium. The chambers of the heart consist of the upper atria and the lower ventricles. The septums are interatrial, interventricular, and atrioventricular. The four valves within the heart are tricuspid, bicuspid, pulmonary semilunar valve, and the aortic semilunar valve.23-58In Summary (cont.)23.2 Superior and inferior vena cavae → right atrium → tricuspid valve → right ventricle → pulmonary semilunar valve → pulmonary trunk → right and left pulmonary arteries → the lungs → pulmonary veins → left atrium → bicuspid valve →left ventricle → aortic semilunar valve → aorta → body organs and tissues.23.3 Heart sounds are described as lubb dubb. Lubb is created when the ventricles contact and the tricuspid and bicuspid valves snap shut. Dubb occurs when the atria contract and the pulmonary and aortic semilunar valves snap shut.23-59In Summary (cont.)23.4 The sinoatrial node generates an impulse to the atrioventricular node. The AV node then sends the impulse to the bundle of His. The bundle splits into the left and right bundle branches and sends the impulse to the Purkinje fibers in the ventricles.23.5 The arterial system is composed of the aorta, arteries, and arterioles (largest to smallest) bring blood from the heart to the body. The capillaries act as the connectors between the arterioles and venules. From the venules, blood returns to the heart via the veins to the superior and inferior vena cavae.23-60In Summary (cont.)23.6 Blood pressure is the force exerted on the inner wall of blood vessels by blood as it flows through vessels. It is highest in arteries and lowest in veins. Clinically, BP refers to the force of blood within the arteries. Blood pressure is largely controlled by the amount of blood pumped out of the heart, but various other events may also raise and lower BP.23-61In Summary (cont.)23.7 Pulmonary circulation: right atrium→ tricuspid valve → right ventricle→pulmonary semilunar valve → pulmonary trunk→pulmonary arteries→lungs→pulmonary veins→left atrium. Systemic circulation: left atrium→bicuspid valve→left ventricle→aortic semilunar valve → aorta → arteries → arterioles→capillaries→venules→veins→vena cavae→right atrium.23-62In Summary (cont.)23.8 The largest artery in the body is the aorta. Other major arteries include lingual, facial, occipital, maxillary, ophthalmic, axillary, brachial, ulnar, radial, intercostals, lumbar, external iliac, common iliac, femoral, popliteal, and tibial. The largest veins in the body are the superior and inferior vena cavae. Other major veins are jugular, brachiocephalic, axillary, brachial, ulnar, radial, intercostals, azygos, gastric, splenic, mesenteric, hepatic portal, hepatic, iliac, femoral, popliteal, and saphenous. 23-63In Summary (cont.)23.9 The components of blood are red blood cells (RBC), white blood cells (WBC), platelets, and plasma. 23.10 Red blood cells carry oxygen and carbon dioxide throughout the body. White blood cells are divided into two types: granulocytes and agranulocytes. Granulocytes include neutrophils, eosinophils, and basophils. Agranulocytes include lymphocytes and monocytes. Platelets are essential in the blood clotting process.23.11 Plasma contains three major proteins: albumins, globulins, and fibrinogen.23-64In Summary (cont.)23.12 Hemostasis is bleeding control. When a blood vessel breaks, the vessel wall spasms and reduces blood loss. Platelets stick to the broken area and to each other, forming a platelet plug. A blood clot occurs when fibrinogen converts to fibrin, which sticks to the damaged area of the blood vessel, creating a meshwork to trap blood cells and platelets, which will remain while tissues repair themselves. 23-65In Summary (cont.)23.13 Blood types are named for the antigen present on the cell surfaces. The “opposite” letter is the name of the antibody present. Blood type A has antigen A and antibody B; blood type B has antigen B and antibody A; blood type AB has antigens A and B and 0 (zero) antibodies; Blood type O has no antigens present and both A and B antibodies.23.14 Rh-positive blood contains the Rh antigen on its RBCs. Rh-negative blood carries no such antigen. 23-66In Summary (cont.)23.15 Due to the antibodies present on different blood types, it is important for blood typing to be done prior to any transfusion. It is equally important to know if a patient’s blood type is positive or negative for the same reason. A negative blood type will “fight” the positive antigen found on a positive blood type. An Rh-negative woman carrying an Rh-positive fetus will develop antibodies against the child’s blood type. 23-67In Summary (cont.)23.16 Many different types of cardiac and blood diseases are described in this chapter. The signs, symptoms, and treatments are as varied as the diseases themselves. The Pathophysiology section of this chapter outlines the most common of these diseases, their signs and symptoms, as well as the treatments.23-68Your work is to discover your world and then with all your heart give yourself to it. ~ BuddhaEnd of Chapter 23