3-cardiovascular system-07-Dec-2018Reference Material I_CardioVascular System.pdf

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Unformatted text preview: 11/15/2008 Objectives  Location Cardiovascular System Heart of heart  Structure of the heart    William T. Budd Virginia Commonwealth University Center for the Study of Biological Complexity Medical Careers College Components of cardiovascular system Layers Coverings Chambers  Structure and function of myocardial valves Location of Heart  Heart Heart-- circulates blood through vessels  Blood vessels    Arteries- away from heart ArteriesVeins-- towards heart Veins Capillaries-- location of internal respiration Capillaries  Blood Blood-- transport medium Coverings of the heart • posterior to sternum • medial to lungs • anterior to vertebral column • base lies beneath 2nd rib • apex at 5th intercostal space • lies upon diaphragm Coverings of Heart Pericardium-loose fitting, double layered sac Visceral pericardium-serous membrane that is on the surface of the heart muscle Parietal pericardium- inner layer of sac; secretes pericardial fluid Pericardial fluid- (Serous fluid)-fluid that is between the parietal and visceral pericardium which prevents friction as the heart beats. 1 11/15/2008 Layers of heart tissue Endocardium  Epicardium Inner lining  Myocardium Smooth surface that permits blood to move easily through the heart without agglutination.  Endocardium Continuous with lining of blood vessels Myocardium Middle layer made of cardiac muscle Forms the bulk of the heart wall Contains the septumseptum - a thick muscular wall that completely separates the blood in the right side of the heart from the blood in the left side. Epicardium Protective, outer layer of the heart wall same as the visceral pericardium The coronary blood vessels that nourish the heart wall are located here Wall of the Heart Endocardium – lines the heart chambers Myocardium – Strong, muscular layer of heart Epicardium – Outer, serous layer of heart 2 11/15/2008 Chambers Right Atrium Thinner wall than ventricles  Receives deoxygenated blood from vena cava  Passes blood through tricuspid valve into right ventricle  Chambers Right Ventricle Thicker wall than atria  Comprises most of anterior surface of heart  Circulates deoxygenated blood to lungs through the pulmonic valve into pulmonary trunk  Chambers Left Atrium Receives freshly oxygenated blood from pulmonary vein  Passes blood to left ventricle through mitral valve  Chambers Left Ventricle Receives blood from left atrium  Thickest myocardial wall  Forms apex of heart  Sends blood to systemic circulation via aorta  3 11/15/2008 Septa  Interatrial septum     Muscular division b/w atria Foramen ovaleovale- opening in fetus Fossa ovalisovalis- shallow depression; remnants of foramen ovale Interventricular septum   Thick muscular wall Seperates ventricles Semilunar valves Heart Valves Function- prevent Functionblood from flowing backwards  Responds to changes in pressure  Two types of valves in heart     Located at exit of ventricles, originiate from endothelial lining of veins  Heart contains two semilunar valves   Atrioventricular valves (AV) Semi--lunar valves Semi Atrioventricular Valves Valve cusps are connected to papillary muscles  Chordae tendineaetendineaetiny collagen cords that anchor cusps of valve to papillary muscles  Pulmonic Aortic (Frequently damaged by Htn Htn)) Atrioventricular Valves  Left AV valve (Mitral, bicuspid)    Contains 2 cusps Subject to abuse Right AV valve (Tricuspid)   Contains 3 cusps Not subjected to great abuses 4 11/15/2008 Vessels of Heart Coronary Arteries Aorta Vena Cava Pulmonary Veins Pulmonary Trunk and pulmonary arteries •2 Main Coronary Arteries •Right CA- branches into some marginal arteries; supplies RV and posterior of heart •Left CA- branches into AIA (LAD) and circumflex; supplies LV Coronary Veins  Transport deoxygenated blood to coronary sinus  Coronary Sinus drains into RA Contractile Cells of Heart  Remember myosin and actin  Presence of calcium in cytoplasm leads to contraction  Action potential is 30X longer than skeletal muscle Cardiac Myocyte Physiology  Striated cells  Adhere to sliding filament theory Shorter cells, branched, one nucleus per cell  Connected tightly by intercalated disks  Contain gap junctions  De Polarization Re Na+ Na+ Na+ Na+ Na+ K+ Na+ K+ K+ Na+ K+ - 70mV Na+ K+ Na+ 30 mV 130 mV K+ Cardiac Cell Ca++ Ca++ Ca++ 5 11/15/2008 Conduction System  Cardiac cells are automaticitic   Conduction System Located in  They can depolarize spontaneously  Autorhythmic cells      Non-contractile cells, Nonself--excitable, self generate spontaneous action potentials, Trigger heart contractions    SA node AV node AV bundle Bundle branches Purkinkie system Intrinsic Rates  Three potential areas capable of beginning cardiac conduction    SA NodeNode- Located in right atria; 6060-100 bpm AV NodeNode- Located at AV junction; 4040-60 bpm Ventricular SystemSystem- Ventricles; < 40 • Rate depends upon where in ventricles conduction originates Atrial Depolarization Visualized as P wave  Normal duration is 0.12--0.16 0.12 seconds  Atrial Delay Visualized as PR interval  Normal duration is 0.12-- 0.20 0.12 seconds  6 11/15/2008 Ventricular Depolarization Visualized as QRS complex  Normal duration is less than 0.12 seconds  Ventricular Repolarization Visualized as T wave  Normal duration is 0.16-- 0.20 0.16 seconds  Absolute and relative period of refraction  Innervation of heart  Heart rate can be influenced by autonomic nervous system  Sympathetic  Speeds up heart rate and increases force of contraction  Parasympathetic  Slows down heart rate 7 ...
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