Chapter 19



Chapter 19 Blood19-5 White Blood CellsWhite Blood Cells (WBCs)Also called leukocytes Do not have hemoglobinHave nuclei and other organelles WBC functionsDefend against pathogensRemove toxins and wastesAttack abnormal cells19-5 White Blood CellsWBC Circulation and MovementMost WBCs in:Connective tissue properLymphatic system organs Small numbers in blood5000 to 10,000 per microliter19-5 White Blood CellsWBC Circulation and MovementFour Characteristics of Circulating WBCsCan migrate out of bloodstreamHave amoeboid movementAttracted to chemical stimuli (positive chemotaxis)Some are phagocyticNeutrophils, eosinophils, and monocytes19-5 White Blood CellsTypes of WBCsNeutrophilsEosinophilsBasophilsMonocytesLymphocytes19-5 White Blood CellsNeutrophils Also called polymorphonuclear leukocytes 50–70 percent of circulating WBCsPale cytoplasm granules with:Lysosomal enzymesBactericides (hydrogen peroxide and superoxide)19-5 White Blood CellsNeutrophil Action Very active, first to attack bacteriaEngulf and digest pathogensDegranulationRemoving granules from cytoplasmDefensins (peptides from lysosomes) attack pathogen membranesRelease prostaglandins and leukotrienesForm pus19-5 White Blood CellsEosinophils (Acidophils)2–4 percent of circulating WBCsAttack large parasitesExcrete toxic compoundsNitric oxideCytotoxic enzymesAre sensitive to allergens Control inflammation with enzymes that counteract inflammatory effects of neutrophils and mast cells19-5 White Blood CellsBasophilsAre less than 1 percent of circulating WBCsAccumulate in damaged tissueRelease histamineDilates blood vesselsRelease heparinPrevents blood clotting 19-5 White Blood CellsMonocytes 2–8 percent of circulating WBCsAre large and sphericalEnter peripheral tissues and become macrophagesEngulf large particles and pathogensSecrete substances that attract immune system cells and fibroblasts to injured area19-5 White Blood CellsLymphocytes20–40 percent of circulating WBCsAre larger than RBCsMigrate in and out of bloodMostly in connective tissues and lymphoid organsAre part of the body’s specific defense system19-5 White Blood CellsThree Classes of Lymphocytes T cellsCell-mediated immunityAttack foreign cells directly19-5 White Blood CellsThree Classes of Lymphocytes B cellsHumoral immunityDifferentiate into plasma cells Synthesize antibodies Natural killer (NK) cellsDetect and destroy abnormal tissue cells (cancers)19-5 White Blood CellsThe Differential Count and Changes in WBC ProfilesDetects changes in WBC populationsInfections, inflammation, and allergic reactions19-5 White Blood CellsWBC DisordersLeukopeniaAbnormally low WBC countLeukocytosisAbnormally high WBC countLeukemiaExtremely high WBC count19-5 White Blood CellsWBC ProductionAll blood cells originate from hemocytoblastsWhich produce progenitor cells called myeloid stem cells and lymphoid stem cells19-5 White Blood CellsWBC ProductionMyeloid stem cells Produce all WBCs except lymphocytesLymphoid stem cellsLymphopoiesis – the production of lymphocytes19-5 White Blood CellsWBC DevelopmentWBCs, except monocytesDevelop in bone marrowMonocytesDevelop into macrophages in peripheral tissues19-5 White Blood CellsRegulation of WBC ProductionColony-stimulating factors (CSFs)Hormones that regulate blood cell populationsM-CSF stimulates monocyte productionG-CSF stimulates production of granulocytes (neutrophils, eosinophils, and basophils) GM-CSF stimulates granulocyte and monocyte productionMulti-CSF accelerates production of granulocytes, monocytes, platelets, and RBCsCh 20An Introduction to the Cardiovascular SystemThe Pulmonary CircuitCarries blood to and from gas exchange surfaces of lungsThe Systemic CircuitCarries blood to and from the bodyBlood alternates between pulmonary circuit and systemic circuitAn Introduction to the Cardiovascular SystemThree Types of Blood VesselsArteriesCarry blood away from heartVeinsCarry blood to heart CapillariesNetworks between arteries and veinsAn Introduction to the Cardiovascular SystemCapillariesAlso called exchange vessels Exchange materials between blood and tissuesMaterials include dissolved gases, nutrients, waste products An Introduction to the Cardiovascular SystemFour Chambers of the Heart Right atriumCollects blood from systemic circuit Right ventriclePumps blood to pulmonary circuit Left atriumCollects blood from pulmonary circuit Left ventriclePumps blood to systemic circuit 20-1 Anatomy of the HeartThe HeartGreat veins and arteries at the basePointed tip is apexSurrounded by pericardial sacSits between two pleural cavities in the mediastinum20-1 Anatomy of the HeartThe PericardiumDouble lining of the pericardial cavity Visceral pericardiumInner layer of pericardiumParietal pericardiumOuter layerForms inner layer of pericardial sac 20-1 Anatomy of the HeartThe PericardiumPericardial cavityIs between parietal and visceral layers Contains pericardial fluidPericardial sac Fibrous tissueSurrounds and stabilizes heart20-1 Anatomy of the HeartSuperficial Anatomy of the HeartAtriaThin-walledExpandable outer auricle (atrial appendage) 20-1 Anatomy of the HeartSuperficial Anatomy of the HeartSulciCoronary sulcus divides atria and ventriclesAnterior interventricular sulcus and posterior interventricular sulcusSeparate left and right ventriclesContain blood vessels of cardiac muscle20-1 Anatomy of the HeartThe Heart Wall Epicardium Myocardium Endocardium20-1 Anatomy of the HeartEpicardium (Outer Layer) Visceral pericardium Covers the heart20-1 Anatomy of the HeartMyocardium (Middle Layer)Muscular wall of the heartConcentric layers of cardiac muscle tissueAtrial myocardium wraps around great vesselsTwo divisions of ventricular myocardiumEndocardium (Inner Layer)Simple squamous epithelium20-1 Anatomy of the HeartCardiac Muscle TissueIntercalated discsInterconnect cardiac muscle cellsSecured by desmosomes Linked by gap junctionsConvey force of contraction Propagate action potentials20-1 Anatomy of the HeartCharacteristics of Cardiac Muscle CellsSmall sizeSingle, central nucleusBranching interconnections between cellsIntercalated discs20-1 Anatomy of the HeartInternal Anatomy and OrganizationInteratrial septum separates atria Interventricular septum separates ventricles20-1 Anatomy of the HeartInternal Anatomy and OrganizationAtrioventricular (AV) valvesConnect right atrium to right ventricle and left atrium to left ventricle Are folds of fibrous tissue that extend into openings between atria and ventricles Permit blood flow in one directionFrom atria to ventricles20-1 Anatomy of the HeartThe Right AtriumSuperior vena cavaReceives blood from head, neck, upper limbs, and chestInferior vena cava Receives blood from trunk, viscera, and lower limbsCoronary sinusCardiac veins return blood to coronary sinus Coronary sinus opens into right atrium 20-1 Anatomy of the HeartThe Right AtriumForamen ovaleBefore birth, is an opening through interatrial septum Connects the two atriaSeals off at birth, forming fossa ovalis20-1 Anatomy of the HeartThe Right AtriumPectinate musclesContain prominent muscular ridges On anterior atrial wall and inner surfaces of right auricle 20-1 Anatomy of the HeartThe Right VentricleFree edges attach to chordae tendineae from papillary muscles of ventriclePrevent valve from opening backwardRight atrioventricular (AV) valve Also called tricuspid valveOpening from right atrium to right ventricle Has three cuspsPrevents backflow20-1 Anatomy of the HeartThe Right VentricleTrabeculae carneaeMuscular ridges on internal surface of right (and left) ventricle Includes moderator bandRidge contains part of conducting systemCoordinates contractions of cardiac muscle cells20-1 Anatomy of the HeartThe Pulmonary CircuitConus arteriosus (superior end of right ventricle) leads to pulmonary trunkPulmonary trunk divides into left and right pulmonary arteries Blood flows from right ventricle to pulmonary trunk through pulmonary valvePulmonary valve has three semilunar cusps 20-1 Anatomy of the HeartThe Left AtriumBlood gathers into left and right pulmonary veins Pulmonary veins deliver to left atriumBlood from left atrium passes to left ventricle through left atrioventricular (AV) valveA two-cusped bicuspid valve or mitral valve20-1 Anatomy of the HeartThe Left VentricleHolds same volume as right ventricleIs larger; muscle is thicker and more powerfulSimilar internally to right ventricle but does not have moderator band20-1 Anatomy of the HeartThe Left VentricleSystemic circulationBlood leaves left ventricle through aortic valve into ascending aortaAscending aorta turns (aortic arch) and becomes descending aorta20-1 Anatomy of the HeartStructural Differences between the Left and Right VentriclesRight ventricle wall is thinner, develops less pressure than left ventricle Right ventricle is pouch-shaped, left ventricle is round20-1 Anatomy of the HeartThe Heart ValvesTwo pairs of one-way valves prevent backflow during contractionAtrioventricular (AV) valves Between atria and ventriclesBlood pressure closes valve cusps during ventricular contractionPapillary muscles tense chordae tendineae to prevent valves from swinging into atria20-1 Anatomy of the HeartThe Heart ValvesSemilunar valves Pulmonary and aortic tricuspid valvesPrevent backflow from pulmonary trunk and aorta into ventriclesHave no muscular supportThree cusps support like tripod 20-1 Anatomy of the HeartAortic Sinuses At base of ascending aorta Sacs that prevent valve cusps from sticking to aortaOrigin of right and left coronary arteries 20-1 Anatomy of the HeartConnective Tissues and the Cardiac Skeleton Connective tissue fibersPhysically support cardiac muscle fibersDistribute forces of contractionAdd strength and prevent overexpansion of heartProvide elasticity that helps return heart to original size and shape after contraction20-1 Anatomy of the HeartThe Cardiac Skeleton Four bands around heart valves and bases of pulmonary trunk and aortaStabilize valves Electrically insulate ventricular cells from atrial cells20-1 Anatomy of the HeartThe Blood Supply to the Heart = Coronary circulationSupplies blood to muscle tissue of heartCoronary arteries and cardiac veins20-1 Anatomy of the HeartThe Coronary Arteries Left and rightOriginate at aortic sinusesHigh blood pressure, elastic rebound forces blood through coronary arteries between contractions20-1 Anatomy of the HeartRight Coronary Artery Supplies blood to:Right atriumPortions of both ventriclesCells of sinoatrial (SA) and atrioventricular nodes Marginal arteries (surface of right ventricle)Posterior interventricular artery20-1 Anatomy of the HeartLeft Coronary Artery Supplies blood to:Left ventricleLeft atriumInterventricular septum20-1 Anatomy of the HeartTwo Main Branches of Left Coronary Artery Circumflex artery Anterior interventricular artery Arterial AnastomosesInterconnect anterior and posterior interventricular arteries Stabilize blood supply to cardiac muscle20-1 Anatomy of the HeartThe Cardiac VeinsGreat cardiac veinDrains blood from area of anterior interventricular artery into coronary sinusAnterior cardiac veinsEmpty into right atrium Posterior cardiac vein, middle cardiac vein, and small cardiac veinEmpty into great cardiac vein or coronary sinus20-1 Anatomy of the HeartHeart Disease – Coronary Artery DiseaseCoronary artery disease (CAD) Areas of partial or complete blockage of coronary circulationCardiac muscle cells need a constant supply of oxygen and nutrients Reduction in blood flow to heart muscle produces a corresponding reduction in cardiac performance Reduced circulatory supply, coronary ischemia, results from partial or complete blockage of coronary arteries20-1 Anatomy of the HeartHeart Disease – Coronary Artery DiseaseUsual cause is formation of a fatty deposit, or atherosclerotic plaque, in the wall of a coronary vessel The plaque, or an associated thrombus (clot), then narrows the passageway and reduces blood flowSpasms in smooth muscles of vessel wall can further decrease or stop blood flow One of the first symptoms of CAD is commonly angina pectoris20-1 Anatomy of the HeartHeart Disease – Coronary Artery DiseaseAngina pectorisIn its most common form, a temporary ischemia develops when the workload of the heart increasesAlthough the individual may feel comfortable at rest, exertion or emotional stress can produce a sensation of pressure, chest constriction, and pain that may radiate from the sternal area to the arms, back, and neck20-1 Anatomy of the HeartHeart Disease – Coronary Artery DiseaseMyocardial infarction (MI), or heart attackPart of the coronary circulation becomes blocked, and cardiac muscle cells die from lack of oxygenThe death of affected tissue creates a nonfunctional area known as an infarctHeart attacks most commonly result from severe coronary artery disease (CAD) 20-1 Anatomy of the HeartHeart Disease – Coronary Artery DiseaseMyocardial infarction (MI), or heart attackConsequences depend on the site and nature of the circulatory blockageIf it occurs near the start of one of the coronary arteries: The damage will be widespread and the heart may stop beatingIf the blockage involves one of the smaller arterial branches:The individual may survive the immediate crisis but may have many complications such as reduced contractility and cardiac arrhythmias20-1 Anatomy of the HeartHeart Disease – Coronary Artery DiseaseMyocardial infarction (MI), or heart attackA crisis often develops as a result of thrombus formation at a plaque (the most common cause of an MI), a condition called coronary thrombosisA vessel already narrowed by plaque formation may also become blocked by a sudden spasm in the smooth muscles of the vascular wallIndividuals having an MI experience intense pain, similar to that felt in angina, but persisting even at rest 20-1 Anatomy of the HeartHeart Disease – Coronary Artery DiseaseMyocardial infarction (MI), or heart attackPain does not always accompany a heart attack; therefore, the condition may go undiagnosed and may not be treated before a fatal MI occursA myocardial infarction can usually be diagnosed with an ECG and blood studiesDamaged myocardial cells release enzymes into the circulation, and these elevated enzymes can be measured in diagnostic blood tests The enzymes include:Cardiac troponin T, Cardiac troponin I, A special form of creatinine phosphokinase, CK-MB20-1 Anatomy of the HeartHeart Disease – Coronary Artery DiseaseTreatment of CAD and myocardial infarctionAbout 25 percent of MI patients die before obtaining medical assistance 65 percent of MI deaths among those under age 50 occur within an hour after the initial infarction20-1 Anatomy of the HeartHeart Disease – Coronary Artery DiseaseTreatment of CAD and myocardial infarctionRisk factor modificationStop smokingHigh blood pressure treatment Dietary modification to lower cholesterol and promote weight loss Stress reductionIncreased physical activity (where appropriate)20-1 Anatomy of the HeartHeart Disease – Coronary Artery DiseaseTreatment of CAD and myocardial infarctionDrug treatmentDrugs that reduce coagulation and therefore the risk of thrombosis, such as aspirin and coumadinDrugs that block sympathetic stimulation (propranolol or metoprolol)Drugs that cause vasodilation, such as nitroglycerinDrugs that block calcium movement into the cardiac and vascular smooth muscle cells (calcium channel blockers)In a myocardial infarction, drugs to relieve pain, fibrinolytic agents to help dissolve clots, and oxygen20-1 Anatomy of the HeartHeart Disease – Coronary Artery DiseaseTreatment of CAD and myocardial infarctionNoninvasive surgeryAtherectomyBlockage by a single, soft plaque may be reduced with the aid of a long, slender catheter inserted into a coronary artery to the plaque20-1 Anatomy of the HeartHeart Disease – Coronary Artery DiseaseTreatment of CAD and myocardial infarctionNoninvasive surgeryBalloon angioplastyThe tip of the catheter contains an inflatable balloon Once in position, the balloon is inflated, pressing the plaque against the vessel wallsBecause plaques commonly redevelop after angioplasty, a fine tubular wire mesh called a stent may be inserted into the vessel, holding it open20-1 Anatomy of the HeartHeart Disease – Coronary Artery DiseaseTreatment of CAD and myocardial infarctionCoronary artery bypass graft (CABG)In a coronary artery bypass graft, a small section is removed from either a small artery or a peripheral vein and is used to create a detour around the obstructed portion of a coronary arteryAs many as four coronary arteries can be rerouted this way during a single operation The procedures are named according to the number of vessels repaired, so we speak of single, double, triple, or quadruple coronary bypasses20-2 The Conducting SystemHeartbeatA single contraction of the heartThe entire heart contracts in seriesFirst the atriaThen the ventricles 20-2 The Conducting SystemCardiac PhysiologyTwo types of cardiac muscle cells Conducting system Controls and coordinates heartbeat Contractile cellsProduce contractions that propel blood20-2 The Conducting SystemThe Cardiac Cycle Begins with action potential at SA nodeTransmitted through conducting systemProduces action potentials in cardiac muscle cells (contractile cells)Electrocardiogram (ECG or EKG)Electrical events in the cardiac cycle can be recorded on an electrocardiogram20-2 The Conducting SystemThe Conducting SystemA system of specialized cardiac muscle cellsInitiates and distributes electrical impulses that stimulate contraction AutomaticityCardiac muscle tissue contracts automatically20-2 The Conducting SystemStructures of the Conducting System Sinoatrial (SA) node – wall of right atriumAtrioventricular (AV) node – junction between atria and ventriclesConducting cells – throughout myocardium20-2 The Conducting SystemConducting CellsInterconnect SA and AV nodesDistribute stimulus through myocardiumIn the atriaInternodal pathwaysIn the ventriclesAV bundle and the bundle branches20-2 The Conducting SystemPrepotentialAlso called pacemaker potentialResting potential of conducting cellsGradually depolarizes toward thresholdSA node depolarizes first, establishing heart rate20-2 The Conducting SystemHeart RateSA node generates 80–100 action potentials per minuteParasympathetic stimulation slows heart rateAV node generates 40–60 action potentials per minute20-2 The Conducting SystemThe Sinoatrial (SA) NodeIn posterior wall of right atriumContains pacemaker cellsConnected to AV node by internodal pathwaysBegins atrial activation (Step 1)20-2 The Conducting SystemThe Atrioventricular (AV) NodeIn floor of right atriumReceives impulse from SA node (Step 2)Delays impulse (Step 3)Atrial contraction begins20-2 The Conducting SystemThe AV Bundle In the septumCarries impulse to left and right bundle branchesWhich conduct to Purkinje fibers (Step 4)And to the moderator bandWhich conducts to papillary muscles20-2 The Conducting SystemPurkinje FibersDistribute impulse through ventricles (Step 5)Atrial contraction is completedVentricular contraction begins20-2 The Conducting SystemAbnormal Pacemaker FunctionBradycardia – abnormally slow heart rateTachycardia – abnormally fast heart rateEctopic pacemakerAbnormal cells Generate high rate of action potentialsBypass conducting systemDisrupt ventricular contractions20-2 The Conducting SystemThe Electrocardiogram (ECG or EKG)A recording of electrical events in the heartObtained by electrodes at specific body locationsAbnormal patterns diagnose damage20-2 The Conducting SystemFeatures of an ECG P waveAtria depolarizeQRS complexVentricles depolarizeT waveVentricles repolarize20-2 The Conducting SystemTime Intervals between ECG WavesP–R intervalFrom start of atrial depolarizationTo start of QRS complexQ–T intervalFrom ventricular depolarizationTo ventricular repolarization20-3 The Cardiac CycleThe Cardiac Cycle Is the period between the start of one heartbeat and the beginning of the next Includes both contraction and relaxation20-3 The Cardiac CycleTwo Phases of the Cardiac CycleWithin any one chamberSystole (contraction)Diastole (relaxation)20-3 The Cardiac CycleBlood PressureIn any chamberRises during systoleFalls during diastoleBlood flows from high to low pressureControlled by timing of contractionsDirected by one-way valves20-3 The Cardiac CycleCardiac Cycle and Heart RateAt 75 beats per minute (bpm)Cardiac cycle lasts about 800 msecWhen heart rate increasesAll phases of cardiac cycle shorten, particularly diastole20-3 The Cardiac CyclePhases of the Cardiac CycleAtrial systoleAtrial diastoleVentricular systoleVentricular diastole20-3 The Cardiac CycleAtrial SystoleAtrial systole Atrial contraction beginsRight and left AV valves are openAtria eject blood into ventriclesFilling ventriclesAtrial systole ends AV valves closeVentricles contain maximum blood volumeKnown as end-diastolic volume (EDV)20-3 The Cardiac CycleVentricular Systole Ventricles contract and build pressureAV valves close causing isovolumetric contraction Ventricular ejectionVentricular pressure exceeds vessel pressure opening the semilunar valves and allowing blood to leave the ventricleAmount of blood ejected is called the stroke volume (SV)20-3 The Cardiac CycleVentricular SystoleVentricular pressure fallsSemilunar valves closeVentricles contain end-systolic volume (ESV), about 40 percent of end-diastolic volume20-3 The Cardiac CycleVentricular DiastoleVentricular diastole Ventricular pressure is higher than atrial pressureAll heart valves are closedVentricles relax (isovolumetric relaxation)Atrial pressure is higher than ventricular pressureAV valves openPassive atrial filling Passive ventricular filling20-3 The Cardiac CycleHeart SoundsS1Loud soundsProduced by AV valvesS2Loud soundsProduced by semilunar valves 20-3 The Cardiac CycleS3, S4 Soft soundsBlood flow into ventricles and atrial contractionHeart MurmurSounds produced by regurgitation through valves20-4 CardiodynamicsCardiodynamicsThe movement and force generated by cardiac contractionsEnd-diastolic volume (EDV)End-systolic volume (ESV)Stroke volume (SV) SV = EDV – ESVEjection fractionThe percentage of EDV represented by SV20-4 CardiodynamicsCardiac Output (CO)The volume pumped by left ventricle in one minuteCO = HR SVCO = cardiac output (mL/min)HR = heart rate (beats/min)SV = stroke volume (mL/beat)20-4 CardiodynamicsFactors Affecting Cardiac OutputCardiac outputAdjusted by changes in heart rate or stroke volumeHeart rateAdjusted by autonomic nervous system or hormonesStroke volumeAdjusted by changing EDV or ESV20-4 CardiodynamicsAutonomic Innervation Cardiac plexuses innervate heartVagus nerves (N X) carry parasympathetic preganglionic fibers to small ganglia in cardiac plexusCardiac centers of medulla oblongataCardioacceleratory center controls sympathetic neurons (increases heart rate)Cardioinhibitory center controls parasympathetic neurons (slows heart rate)20-4 CardiodynamicsAutonomic Innervation Cardiac reflexes Cardiac centers monitor:Blood pressure (baroreceptors)Arterial oxygen and carbon dioxide levels (chemoreceptors)Cardiac centers adjust cardiac activityAutonomic tone Dual innervation maintains resting tone by releasing ACh and NEFine adjustments meet needs of other systems20-4 CardiodynamicsEffects on the SA NodeMembrane potential of pacemaker cellsLower than other cardiac cellsRate of spontaneous depolarization depends on:Resting membrane potentialRate of depolarization20-4 CardiodynamicsEffects on the SA NodeSympathetic and parasympathetic stimulationGreatest at SA node (heart rate)ACh (parasympathetic stimulation)Slows the heartNE (sympathetic stimulation)Speeds the heart20-4 CardiodynamicsAtrial ReflexAlso called Bainbridge reflexAdjusts heart rate in response to venous returnStretch receptors in right atriumTrigger increase in heart rateThrough increased sympathetic activity20-4 CardiodynamicsHormonal Effects on Heart RateIncrease heart rate (by sympathetic stimulation of SA node)Epinephrine (E)Norepinephrine (NE)Thyroid hormone 20-4 CardiodynamicsFactors Affecting the Stroke VolumeThe EDV – amount of blood a ventricle contains at the end of diastoleFilling timeDuration of ventricular diastoleVenous returnRate of blood flow during ventricular diastole20-4 CardiodynamicsPreloadThe degree of ventricular stretching during ventricular diastoleDirectly proportional to EDVAffects ability of muscle cells to produce tension20-4 CardiodynamicsThe EDV and Stroke VolumeAt restEDV is lowMyocardium stretches lessStroke volume is lowWith exerciseEDV increasesMyocardium stretches moreStroke volume increases20-4 CardiodynamicsThe Frank–Starling PrincipleAs EDV increases, stroke volume increasesPhysical LimitsVentricular expansion is limited by:Myocardial connective tissueThe cardiac (fibrous) skeletonThe pericardial sac20-4 CardiodynamicsEnd-Systolic Volume (ESV)Is the amount of blood that remains in the ventricle at the end of ventricular systole 20-4 CardiodynamicsThree Factors That Affect ESV PreloadVentricular stretching during diastole ContractilityForce produced during contraction, at a given preload AfterloadTension the ventricle produces to open the semilunar valve and eject blood20-4 CardiodynamicsContractility Is affected by:Autonomic activity Hormones20-4 CardiodynamicsEffects of Autonomic Activity on ContractilitySympathetic stimulationNE released by postganglionic fibers of cardiac nervesEpinephrine and NE released by adrenal medullaeCauses ventricles to contract with more forceIncreases ejection fraction and decreases ESV20-4 CardiodynamicsEffects of Autonomic Activity on ContractilityParasympathetic activityAcetylcholine released by vagus nervesReduces force of cardiac contractions20-4 CardiodynamicsHormones Many hormones affect heart contractionPharmaceutical drugs mimic hormone actions Stimulate or block beta receptorsAffect calcium ions (e.g., calcium channel blockers)20-4 CardiodynamicsAfterload Is increased by any factor that restricts arterial blood flow As afterload increases, stroke volume decreases20-4 CardiodynamicsSummary: The Control of Cardiac OutputHeart rate control factorsAutonomic nervous systemSympathetic and parasympathetic Circulating hormones Venous return and stretch receptors20-4 CardiodynamicsSummary: The Control of Cardiac OutputStroke volume control factors EDVFilling time and rate of venous returnESVPreload, contractility, afterload20-4 CardiodynamicsCardiac ReserveThe difference between resting and maximal cardiac outputs20-4 CardiodynamicsThe Heart and Cardiovascular SystemCardiovascular regulationEnsures adequate circulation to body tissues Cardiovascular centersControl heart and peripheral blood vesselsCardiovascular system responds to:Changing activity patternsCirculatory emergencies Ch 22An Introduction to the Lymphatic System and ImmunityPathogens Microscopic organisms that cause disease:VirusesBacteriaFungiParasitesEach attacks in a specific way 22-1 Overview of the Lymphatic SystemThe Lymphatic SystemProtects us against diseaseLymphatic system cells respond to:Environmental pathogensToxinsAbnormal body cells, such as cancers 22-1 Overview of the Lymphatic SystemSpecific Defenses LymphocytesPart of the immune response Identify, attack, and develop immunityTo a specific pathogen22-1 Overview of the Lymphatic SystemThe Immune System ImmunityThe ability to resist infection and disease All body cells and tissues involved in production of immunityNot just lymphatic system 22-1 Overview of the Lymphatic SystemNonspecific Defenses Block or attack any potential infectious organismCannot distinguish one attack from another22-2 Structures of Body DefensesOrganization of the Lymphatic System LymphA fluid similar to plasma but does not have plasma proteins Lymphatic vessels (lymphatics)Carry lymph from peripheral tissues to the venous system Lymphoid tissues and lymphoid organs Lymphocytes, phagocytes, and other immune system cells22-2 Structures of Body DefensesFunction of the Lymphatic SystemTo produce, maintain, and distribute lymphocytesLymphocyte Production Lymphocytes are producedIn lymphoid tissues (e.g., tonsils)Lymphoid organs (e.g., spleen, thymus)In red bone marrowLymphocyte distribution Detects problemsTravels into site of injury or infection22-2 Structures of Body DefensesLymphocyte Circulation From blood to interstitial fluid through capillariesReturns to venous blood through lymphatic vesselsThe Circulation of FluidsFrom blood plasma to lymph and back to the venous systemTransports hormones, nutrients, and waste products22-2 Structures of Body DefensesLymphatic Vessels Are vessels that carry lymph Lymphatic system begins with smallest vesselsLymphatic capillaries (terminal lymphatics)22-2 Structures of Body DefensesLymphatic Capillaries Differ from blood capillaries in four waysStart as pockets rather than tubesHave larger diametersHave thinner wallsFlat or irregular outline in sectional view22-2 Structures of Body DefensesLymphatic Capillaries Endothelial cells loosely bound together with overlapOverlap acts as one-way valveAllows fluids, solutes, viruses, and bacteria to enterPrevents return to intercellular space22-2 Structures of Body DefensesLymph FlowFrom lymphatic capillaries to larger lymphatic vessels containing one-way valvesLymphatic vessels travel with veinsLactealsAre special lymphatic capillaries in small intestineTransport lipids from digestive tract22-2 Structures of Body DefensesLymphatic VesselsSuperficial lymphatics Deep lymphatics Are located in:SkinMucous membranesSerous membranes lining body cavities22-2 Structures of Body DefensesSuperficial and Deep Lymphatics The deep lymphatics Are larger vessels that accompany deep arteries and veinsSuperficial and deep lymphatics Join to form large lymphatic trunks Trunks empty into two major collecting vessels Thoracic duct Right lymphatic duct 22-2 Structures of Body DefensesMajor Lymph-Collecting VesselsThe base of the thoracic duct Expands into cisterna chyli Cisterna chyli receives lymph from:Right and left lumbar trunks Intestinal trunk22-2 Structures of Body DefensesThe Inferior Segment of Thoracic Duct Collects lymph from:Left bronchomediastinal trunkLeft subclavian trunkLeft jugular trunkEmpties into left subclavian vein22-2 Structures of Body DefensesThe Right Lymphatic Duct Collects lymph from:Right jugular trunkRight subclavian trunkRight bronchomediastinal trunk Empties into right subclavian vein22-2 Structures of Body DefensesLymphedema Blockage of lymph drainage from a limbCauses severe swellingInterferes with immune system function LymphocytesMake up 20–40 percent of circulating leukocytesMost are stored, not circulating22-2 Structures of Body DefensesTypes of Lymphocytes T cellsThymus-dependent B cellsBone marrow-derived NK cellsNatural killer cells22-2 Structures of Body DefensesT Cells Make up 80 percent of circulating lymphocytesMain Types of T CellsCytotoxic T (TC) cells Memory T cellsHelper T (TH) cellsSuppressor T (TS) cells22-2 Structures of Body DefensesCytotoxic T CellsAttack cells infected by virusesProduce cell-mediated immunityMemory T CellsFormed in response to foreign substanceRemain in body to give “immunity”Helper T CellsStimulate function of T cells and B cells22-2 Structures of Body DefensesSuppressor T CellsInhibit function of T cells and B cellsRegulatory T CellsAre helper and suppressor T cellsControl sensitivity of immune response22-2 Structures of Body DefensesOther T Cells Inflammatory T cells Suppressor/inducer T cellsB CellsMake up 10–15 percent of circulating lymphocytesDifferentiate (change) into plasma cellsPlasma cells Produce and secrete antibodies (immunoglobulin proteins) 22-2 Structures of Body DefensesAntigens Targets that identify any pathogen or foreign compoundImmunoglobulins (Antibodies)The binding of a specific antibody to its specific target antigen initiates antibody-mediated immunity22-2 Structures of Body DefensesAntibody-Mediated Immunity A chain of events that destroys the target compound or organismNatural Killer (NK) CellsAlso called large granular lymphocytes Make up 5–10 percent of circulating lymphocytesResponsible for immunological surveillanceAttack foreign cells, virus-infected cells, and cancer cells22-2 Structures of Body DefensesLymphocyte Distribution Tissues maintain different T cell and B cell populationsLymphocytes wander through tissuesEnter blood vessels or lymphatics for transport Can survive many years22-2 Structures of Body DefensesLymphocyte Production Also called lymphopoiesis, involves: Bone marrowThymusPeripheral lymphoid tissuesHemocytoblastsIn bone marrow, divide into two types of lymphoid stem cells22-2 Structures of Body DefensesLymphoid Stem Cells Group 1Remains in bone marrow and develop with help of stromal cellsProduces B cells and natural killer cellsGroup 2Migrates to thymusProduces T cells in environment isolated by blood–thymus barrier22-2 Structures of Body DefensesT Cells and B Cells Migrate throughout the bodyTo defend peripheral tissuesRetaining their ability to divideIs essential to immune system function22-2 Structures of Body DefensesDifferentiation B cells differentiateWith exposure to hormone called cytokine (interleukin-7)T cells differentiateWith exposure to several thymic hormones22-2 Structures of Body DefensesLymphoid TissuesConnective tissues dominated by lymphocytesLymphoid NodulesAreolar tissue with densely packed lymphocytesGerminal center contains dividing lymphocytes22-2 Structures of Body DefensesDistribution of Lymphoid Nodules Lymph nodesSpleenRespiratory tract (tonsils)Along digestive, urinary, and reproductive tracts22-2 Structures of Body DefensesThe Lymphatic System and Body DefensesBody defenses provide resistance to fight infection, illness, and diseaseTwo categories of defenses Innate (nonspecific) immunity Adaptive (specific) immunity 22-2 Structures of Body DefensesInnate (Nonspecific) Immunity Always works the same way Against any type of invading agentNonspecific resistanceAdaptive (Specific) Immunity Protects against specific pathogensDepends on activities of lymphocytesSpecific resistance (immunity)Develops after exposure to environmental hazards22-3 Nonspecific DefensesSeven Major Categories of Innate (Nonspecific) Immunity Physical barriers Phagocytes Immune surveillance Interferons Complement Inflammatory response Fever22-3 Nonspecific DefensesPhysical BarriersKeep hazardous materials outside the bodyPhagocytes Attack and remove dangerous microorganismsImmune SurveillanceConstantly monitors normal tissuesWith natural killer cells (NK cells) 22-3 Nonspecific DefensesInterferons Chemical messengers that trigger production of antiviral proteins in normal cellsAntiviral proteinsDo not kill virusesBlock replication in cellComplement System of circulating proteins Assists antibodies in destruction of pathogens22-3 Nonspecific DefensesInflammatory ResponseLocalized, tissue-level response that tends to limit spread of injury or infection FeverA high body temperatureIncreases body metabolismAccelerates defensesInhibits some viruses and bacteria22-3 Nonspecific DefensesPhysical Barriers Outer layer of skinHairEpithelial layers of internal passagewaysSecretions that flush away materialsSweat glands, mucus, and urineSecretions that kill or inhibit microorganismsEnzymes, antibodies, and stomach acid22-3 Nonspecific DefensesTwo Classes of Phagocytes MicrophagesNeutrophils and eosinophilsLeave the bloodstreamEnter peripheral tissues to fight infections22-3 Nonspecific DefensesTwo Classes of Phagocytes MacrophagesLarge phagocytic cells derived from monocytes Distributed throughout bodyMake up monocyte–macrophage system (reticuloendothelial system)22-3 Nonspecific DefensesActivated Macrophages Respond to pathogens in several waysEngulf pathogen and destroy it with lysosomal enzymesBind to pathogen so other cells can destroy itDestroy pathogen by releasing toxic chemicals into interstitial fluid22-3 Nonspecific DefensesTwo Types of Macrophages Fixed macrophages Also called histiocytesStay in specific tissues or organsFor example, dermis and bone marrow Free macrophages Also called wandering macrophagesTravel throughout body22-3 Nonspecific DefensesSpecial Histiocytes Microglia found in central nervous systemKupffer cells found in liver sinusoidsFree MacrophagesSpecial free macrophagesAlveolar macrophages (phagocytic dust cells)22-3 Nonspecific DefensesMovement and PhagocytosisAll macrophages:Move through capillary walls (emigration)Are attracted or repelled by chemicals in surrounding fluids (chemotaxis)Phagocytosis begins:When phagocyte attaches to target (adhesion)And surrounds it with a vesicle22-3 Nonspecific DefensesImmunological Surveillance Is carried out by natural killer (NK) cellsActivated NK CellsIdentify and attach to abnormal cell (nonselective)Golgi apparatus in NK cell forms perforin vesiclesVesicles release proteins called perforins (exocytosis)Perforins lyse abnormal plasma membraneAlso attack cancer cells and cells infected with viruses22-3 Nonspecific DefensesImmunological Surveillance Cancer cells With tumor-specific antigens Are identified as abnormal by NK cellsSome cancer cells avoid NK cells (immunological escape)22-3 Nonspecific DefensesImmunological Surveillance Viral infections Cells infected with virusesPresent abnormal proteins on plasma membranesAllow NK cells to identify and destroy them22-3 Nonspecific DefensesInterferons Proteins (cytokines) released by activated lymphocytes and macrophagesCytokinesChemical messengers released by tissue cellsTo coordinate local activitiesTo act as hormones to affect whole body22-3 Nonspecific DefensesThree Types of Interferons Alpha-interferons Produced by leukocytesStimulate NK cells Beta-interferonsSecreted by fibroblastsSlow inflammation Gamma-interferonsSecreted by T cells and NK cellsStimulate macrophage activity22-3 Nonspecific DefensesComplementPlasma contains 30 special complement (C) proteinsThat form complement system and complement antibody actionComplement activationComplements work together in cascadesTwo pathways activate the complement system Classical pathway Alternative pathway22-3 Nonspecific DefensesComplement Activation: The Classical PathwayFast method C1 binds to: Antibody molecule attached to antigen (bacterium)Bound protein acts as enzymeCatalyzes chain reaction22-3 Nonspecific DefensesComplement Activation: The Alternative PathwaySlow method exposed to antigenFactor P (properdin)Factor BFactor D Interact in plasma 22-3 Nonspecific DefensesComplement Activation Both pathways end with:Conversion of inactive complement protein C3To active form C3b22-3 Nonspecific DefensesEffects of Complement ActivationPore formation Destruction of target plasma membranesFive complement proteins join to form membrane attack complex (MAC)Enhancement of phagocytosis by opsonization Complements working with antibodies (opsonins)Histamine releaseIncreases the degree of local inflammation and blood flow22-3 Nonspecific DefensesInflammation Also called inflammatory response A localized responseTriggered by any stimulus that kills cells or injures tissue22-3 Nonspecific DefensesCardinal Signs and Symptoms Swelling (tumor)Redness (rubor)Heat (calor)Pain (dolor) 22-3 Nonspecific DefensesThree Effects of InflammationTemporary repair and barrier against pathogensRetards spread of pathogens into surrounding areasMobilization of local and systemic defensesAnd facilitation of repairs (regeneration)22-3 Nonspecific DefensesProducts of Inflammation NecrosisLocal tissue destruction in area of injuryPusMixture of debris and necrotic tissueAbscessPus accumulated in an enclosed space 22-3 Nonspecific DefensesFever A maintained body temperature above 37.2C (99F)Pyrogens Any material that causes the hypothalamus to raise body temperatureCirculating pathogens, toxins, or antibody complexesEndogenous pyrogens or interleukin-1 (IL-1)Pyrogen released by active macrophagesA cytokine22-4 Specific DefensesAdaptive (Specific) Defenses Specific resistance (immunity)Responds to specific antigensWith coordinated action of T cells and B cells22-4 Specific DefensesSpecific Defenses T CellsProvide cell-mediated immunityDefend against abnormal cells and pathogens inside cellsB Cells Provide antibody-mediated immunityDefend against antigens and pathogens in body fluids22-4 Specific DefensesForms of Immunity Innate Present at birth AdaptiveAfter birth ActiveAntibodies develop after exposure to antigen PassiveAntibodies are transferred from another source22-4 Specific DefensesActive Immunity Naturally acquiredThrough environmental exposure to pathogensArtificially inducedThrough vaccines containing pathogens22-4 Specific DefensesPassive Immunity Naturally acquiredAntibodies acquired from the motherArtificially inducedBy an injection of antibodies22-4 Specific DefensesFour Properties of Immunity Specificity Each T or B cell responds only to a specific antigen and ignores all others VersatilityThe body produces many types of lymphocytesEach fights a different type of antigenActive lymphocyte clones itself to fight specific antigen22-4 Specific DefensesFour Properties of Immunity MemorySome active lymphocytes (memory cells):Stay in circulationProvide immunity against new exposure ToleranceImmune system ignores “normal” antigens (self-antigens) 22-4 Specific DefensesAn Introduction to the Immune ResponseTwo main divisionsCell-mediated immunity (T cells)Antibody-mediated immunity (B cells)22-5 T Cells and ImmunityFour Major Types of T Cells Cytotoxic T cells (also called TC cells)Attack cells infected by virusesResponsible for cell-mediated immunity Memory T cellsClone more of themselves in response to “remembered” antigen Helper T cells (also called TH cells)Stimulate function of T cells and B cells Suppressor T cells (also called TS cells)Inhibit function of T cells and B cells ................
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