A&P - Heart


cardiovascular system


heart, blood, blood vessels2 circulatory patterns: pulmonic and systemic


pulmonic circulation


RV (DOB) -> lungs (exchange) -> LA (OB)


systemic circulation


LV (OB) -> body (exchange) -> RA (DOB)


heart


located in mediastinumbehind sternum, between lungsleft of midline, tipped to front4 chambers


base of the heart


superiorall blood vessels enter and exit


apex of the heart


inferior


right atrium


upper right chamberreceives DOB from body


right ventricle


lower right chamberreceives DOB from RApumps DOB to lungs


left atrium


upper left chamberreceives OB from lungs


left ventricle


lower left chamberlargest chamber, thickest wallreceives OB from LApumps OB to body


auricles


on top of RA and LAincreases volume


interventricular septum


septum between the ventricles


interatrial septum


septum between the atria


foramen ovale


hole in the IAS of a fetusallows blood to move from R to L (fetal lungs immature)


fossa ovalis


closed foramen ovale


atrial septum defect


foramen ovale fails to close after birthmust be surgically repaired


SVC


superior vena cavareturns DOB to the RA from all regions above the heart


IVC


inferior vena cavareturns DOB to the RA from all regions below the heart


CS


coronary sinusreturns the DOB to the RA from the heart itself


PT


pulmonary trunkDOB from RV to lungssplits into L & R pulmonary arteries


PV


pulmonary veins (4 - 2R, 2L)returns OB from the lungs to the LA


aorta


OB from LV to bodylargest BV in the body


tricuspid


R atrioventricular valvebetween RA/RV


bicuspid


aka mitra or L atrioventricularbetween LA/LV


aortic semilunar valve


entrance to aorta


pulmonary semilunar valve


entrance to pulmonary trunk


chordae tendineae


heart strings that attach valves to papillary muscleskeep valves moving one waymaintain tension


epicardium


outer thin covering of the heart


myocardium


thick middle muscle layer of the heart


endocardium


thin, shiny inner lining of the heartlines all cavities and vessels that enter/exit the heart


pericardial sac


thick CT bag2 layers: fibrous (outer) & serous (inner)


conduction system


several masses of nerve tissuecontrols rate, rhythm, force of HBSA -> AV -> Bundle of His -> purkinje fibers


SA node


sinoatrial node aka pacemaker of the heartlocated in upper RAreceives impulses from ANSsends impulses to LA and AV node


AV node


atrioventricular nodelocated in lower RAreceives impulses from SA nodesends impulses down Bundle of His


Bundle of His


runs transverse through IV septumR and L branchesreceives impulses from AV nodesends impulses to apex of heart


purkinje fibers


terminal branch of conduction systemreceives impulses from Bundle of Hissends impulses into ventricular myocardium


EKG


graphical record of electrical activity of the ehart3 waves: P wave, QRS complex, T wave


P wave


atrial depolarizationelectricity moves through both atriaend of P wave - atria contract


QRS complex


ventricular depolarizationelectricity moves through both ventriclesend of QRS complex- ventricles contract


T wave


ventricular repolarizationend of T wave - ventricles relax


auscultation


listening to heart sounds


lubb


heart sound produced when AV valves closelonger, louder sound


dup


heart sound produced when semilunars closeshorter, softer sound


heart murmur


abnormal heart sounds (swishing)


cardiac cycle


all events associated with blood moving through the heart3 stages: ventricular filling, ventricular systole, isovolumetric relaxation


ventricular filling


P-waveoverall pressure in the heart is lowblood enters atria, moves through to ventriclespassive filling (70%) due to gravity and weight of bloodboth cuspids open, both semilunars closedatria contract to empty remaining 30%atria relax


ventricular systole


pressure in ventricles risescuspids closefor 1/10 second, ventricles are completely closed chamberspressure opens semilunarsventricles contract to force blood into aorta and pulmonary trunk (called ventricular


ejection)


isovolumetric relaxation


ventricles rekaxpressure in ventricles dropssemilunars closeventricles again closed chambers


heart rate


normal 75 bpmaffected by age (decreases with age), gender (increased in women), exercise, body temp,


chemicals, ANS


tachycardia


HR > 100


bradycardia


HR < 60


cardiac output


total volume of blood pumped out of each ventricle per minuteformula: CO = HR x SV


stroke volume


amount of blood pumped out of each ventricle per beat3 factors that affect SV: preload, contractility, afterload


cardiac reserve


ability to push cardiac output far above normalseen during exercise, emergency, and stress


preload


amount of stretch on cardiac fibers just before contraction


Frank-Starling Law of the Heart


the greater the strecth, the stronger the contractionexplains why R & L ventricles eject the same volume despite size differences


contractility


strength of contraction of individual cardiac fiberscontrolled by positive and negative inotropic agents


positive inotropes


increase strength of contractionex: epinephrine, norepinephrine, digitalis


negative inotropes


decrease strength of contractionex: anesthesia


afterload


amount of pressure needed in both ventricles to open semilunars


blood pressure


the force exerted on vessel walls by contained bloodaffected by:-blood volume (^ vol ^ BP)-cardiac output (^ output ^ BP)-peripheral resistance (^ resistance ^ BP)-diameter of vessel (small diameter ^ BP)


peripheral resistance


friction encountered by blood as it moves through vessel walls


HIGHEST BP


in aorta and pulmonary trunk just after ventricles contract


LOWEST BO


in SVC, IVC, CS, pulonary veins before blood enters atria


ZERO BP


in atria just before contraction


pulse pressure


difference between systolic and diastolicworking pressure of the blood that moves through the vessels


hypertension


systolic > 140


hypotension


systolic < 100


essential hypertension


BP 220/120 or greater


thrombus


stationary internal blood clot


embolus


thrombus that dislodges and moves


aneurysm


thin spot in the wall of a vessel that causes it to bulge and possible rupture


blood vessels


3 major groups: arteries, veins, capillaries


arteries


carry blood (usually OB) away from the heartlarger of the vesselsempty into arterioles


veins


carry blood (usually DOB) to the heartsupplied by venulesless elastic than arterieslower BP than arterieshave valves to prevent backflow


capillaries


connect arteries and veinsmade of endothelium (simple squamous ET)called microcirculationallows for passage of O2, CO2, nutrients, waste between blood and tissues


tunica interna/intima


inner layer of arteries and veinssimple squamous


tunica media


middle, thickest layer of arteries and veinssmooth muscle w/elastic fibers


tunica externa/adventitia


strongest, outer layer of arteries and veinscollagen w/elastic fibers


anastamosis


life sustaining structures are supplied by a network of several arteriesprovides alternate ways for structures to receive bloodex: circle of willis in the brain


trunk arteries


ascending aorta--R & L coronaryarch of aorta--brachiocephalic----R common corotid----R subclavian--L subclavian--L common corotidabdominal descending--renal arteries--R & L common iliacPIC


trunk veins


----R & L subclavian--brachiocephalic--internal/external jugularsSVC----R & L coronary veins--coronary sinusRA--R & L common iliacIVCPIC


blood


liquid connective tissuecarries O2, nutrients, hormones to tissuescarries waste to lungs, kidneys, sweat glands38.0C, 100.4F55% plasma, 45% formed elementspH 7.35 - 7.453 functions: --transportation--regulation (pH, temp, water content)--protection (antibodies, clotting)


plamsa


thin, watery, yellowish liquid92% H20, 8% solute (protein, hormones, vitamins, nutrients, electrolytes)3 groups of proteins: albumin, globulins, fibrinogen


albumins


54% of plasma proteinsmaintains blood volume, water balance, amount of water entering cells, carrier molecules for facilitated diffusion


globulins


38% of plasma proteinsproduce antibodies


fibrinogen


7% of plasma proteinsclotting


hematopoiesis


formation of blood or blood cellsin embryo: cells formed in liver, spleen, thymus, lymph nodes, bone marrow, and yolk sacafter birth: cells formed in red bone marrow (proximal epiphysis of humerus & femur, flat bones (sternum, ribs), cranial bones, vertebra, and pelvis)


pleuripotent hematopoeitic stem cells


cells that make all blood cells--myeloid stems-----RBCs-----WBCs (neutro, eosino, baso, monocytes)-----thrombocytes--lymphoid stems-----lymphocytes---------plasma cells------------B&T cells


RBCs


no nucleus - ejected before reticulocyte stagelive 120 days - broken down in liver or spleen2 million produced per secondsurrounded by selectively permeable membrane that enclose cytoplasm and hemoglobin


RBC counts


female: 4.8 million/mm3male: 5.4 million/mm3


hemoglobin


made of heme (iron) + globin (protein)O2 binds to iron, CO2 binds to proteintakes up most space inside RBC (1/3 of weight)when RBC destroyed in liver, Hgb breaks down into hemosiderin, bilirubin, globin


hemosiderin


iron pigment that remains in the liverstored and eventually used to make new Hgb


bilirubin


waste productmoves from blood into bile


globin


protein metabolized in the liver


erythropoiesis


production of RBCscontrolled by erythropoietin


renal erythropoietic factor


enzyme produced and released by the kidneys that causes the production of more erythropoietintriggered by excessive blood loss


WBCs


fight infectionall have nucleuslive a few days to several monthscan leave circulatory system and move to sites of infection2 classes: granular and agranular


WBC count


5,000 - 10,000/mm3


leukocytosis


WBC > 10,000


leukopenia


WBC < 5,000


granular WBCs


small grains in cytoplasm3 types: neutrophils, eosinophils, basophils


neutrophils


nucleus has 2-6 lobesfirst WBC to reach site of infectionphagocytes


eosinophils


nucleus has 2 lobesfights parasites and worms


basophils


irregular shaped nucleusinvolved in allergic reactionsproduce 3 chemicals that aid in allergic response: histamine, heparin, seratonin


agranular WBCs


do not have grains in cytoplasm2 types: monocytes and lymphocytes


monocytes


major phagocytes of the bodymore will arrive to site of infection than neutrophilsturn into macrophages on the way to site of infection


macrophages


most active phagocytes in the bodynucleus is kidney shaped2 types: fixed and wandering


lymphocytes


become B cells and T cells


B cells


become plasmal cells that make antibodies to kill bacteria


T cells


make cells that attack and kill viruses


diapedesis


WBC slides out of vessel wall


chemotaxis


WBC moves to site of infection


thrombocytes


plug damaged vessels and secrete chemicals needed for clottingmade from megakaryocytes that shed pieces of cytoplasm, which becomes enclosed by a cell membraneno nucleusoval or disk shapedproduction controlled by thrombopoietinlive 5-9 days - destroyed by liver and spleen


platelet count


250,000 - 400,000/mm3


reticulocyte count


measurement of speed of RBC formation


talquist


test for anemia


hematocrit


# of RBCs/total blood volumemale: 42-54%female: 37-47%


differential WBC


# of each type of WBC per 100neutrophils - 60 - 70basophils - 0.5 - 1eosinophils - 2-4monocytes - 8-10lymphocytes - 20-25


hemostasis


stoppage of bleedingposiive feedback loop that occurs when blood vessel is injured3 steps: vascular spasm, platelet plug formation, clotting


vascular spasm


as blood escapes, it activates stretch receptors in vessel wallvessel contracts rapidly to temporarily reduce blood lossspasm most effecient if injury is cause by dull, blunt object (more receptors stimulated)


platelet plug formation


in a normal vessel, wall and platelets have "+" chargein an injured vessel, "-" charged collagen in tunica adventita is exposed"-" collagen attracts "+" platelets to siteplatelets swell, stick to each other and the collagen, and then blow upgranules inside platelets release more "-" chemicals to attract more "+" platelets


degranulation of the platelet


positive feedback loop that plugs injury


clotting


a process that involves 20+ clotting factors2 pathways: intrinsic, extrinsic


clotting factors


a large group of chemicals that are ALL necessary for proper and efficient clotting


intrinsic clotting


occurs inside blood vesselsmore complex than extrinsic


extrinsic


occurs outside blood vesselfaster than intrinsic


common clotting pathway


both pathways merge


clotting factors


prothrominase - relased when platelet degranulatesprothrombinvitamin kthrombincalciumfibrinogenfibrin