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BIOL 1410 (94)

Cardiovascular System

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Biological Sciences
BIOL 1410
Jennifer Mcleese

Cardiovascular System May-13-13 11:10 AM  Heart, blood vessels, blood  Transport: gases, nutrients, hormones, wastes, heat  Protection: disease, fluid loss (clotting) Heart  In cavity called mediastinum (in thoracic cavity between lungs) Coverings = Pericardium is double walled sac surrounding heart 3 Layers: 1. Fibrous Pericardium o Outer is dense irregular CT 2. Serous Pericardium o 2 parts o Parietal Pericardium: Fused to fibrous pericardium (layers 1 and 2a = pericardial sac) o Visceral Pericardium/Epicardium: Fused to heart surface (part of heart wall)  Between pericardial layers is pericardial cavity with serous fluid (lubricates) 3. Heart Wall has 3 parts a. Epicardium (Stratified Squamous Epithelium and CT) b. Myocardium (Cardiac Muscle) arranged in spiral/circular pattern reinforced with CT c. Endocardium : Simple sq. epith and CT, epithelium/endothelium lines inner surface of heart + blood vessels) Chambers + Associated Blood Vessels 1. Right Atrium  Inferior and superior vena cava  Coronary sinus 2. Left Atrium  4 pulmonary veins 3. Right Ventricle  Pulmonary trunk  Divides to form 2 pulmonary arteries 4. Left Ventricle  Aorta Septa (separate chambers) 1. Interatrial Septum  Separates atria 2. Interventricular septum  Separates ventricles  Deep to interventricular sulcus (external) Fibrous Skeleton  CT fibers around muscle fibers + CT rings between atria and ventricles at the coronary sulcus  Allows openings to remain open at all times (valves open and close)  Provide electrical insulation preventing simultaneous contraction of chambers Valves 1. Atrioventricular (AV valves) a. Bicuspid/Mitral Valve  Left side - 2 cusps b. Tricuspid  Right side - 3 cusps Chordae Tendinaeae: Attach cusps to papillary muscles (cardiac muscle), prevents eversion of cusps 2. Semilunar Valves: 3 cusps each a. Aortic: Between left ventricle and aorta b. Pulmonary: Between right ventricle and pulmonary trunk Cardiac Muscle Cells  Form both contractile myocardium + conduction system Similarities to skeletal muscle: 1. Striated (myofibrils with sarcomeres) 2. Has sarcoplasmic reticulum Differences: 1. Branched (myofibrils with sarcomeres) 2. Uninucleated 3. Intercalated Discs: Region where 2 fibers meet, contain anchoring and gap junctions Conduction System  Cardiac muscle cells modified to produce and conduct electrical impulses (DO NOT CONTRACT) Parts: 1. Sinoatrial (SA) Node: o In right atrium at base of superior vena cava o Generates impulses the fastest- setting pace 2. Atrioventricular (AV) Node: o Base of right atrium 3. Bundle of His  Superior part of interventricular septum  Electrically connects atria to ventricles 4. Bundle of His Branches  Go to each ventricle 5. Purkinje Fibers  Terminal fibers in ventricles only ***ELECTRICAL SIGNAL SPREADS TO CONTRACTILE CARDIAC CELLS THEN THEY CONTRACT*** Circulatory Routes  Closed, double circulation (closed: Blood confined to heart + blood vessels, Double=2 routes pulmonary+systemic) A.Adult Circulation 1. Pulmonary Circulation  Right ventricle to lungs via pulmonary arteries (deoxy blood)  Pick up oxygen in lungs via capillaries  Lungs to left atria via pulmonary veins (oxygenated blood) 2. Systemic Circulation  Left ventricle to organs via aorta (oxygenated)  Organs remove oxygen via capillaries  Organs to right atrium via superior and inferior vena cava (deoxy) Systemic Circulatory Subdivisions: Overall route: left ventricle to right atrium = systemic circulatory Subroutes: Cerebral - brain Hepatic: Liver Coronary: Heart Coronary Circulation (Visible externally)  Left ventricle aorta to right coronary artery, then posterior interventricular artery/marginal artery  Could also go to left coronary artery, then anterior interventricular artery/circumflex artery  All lead to arterioles, capillaries in myocardium, venules, cardiac veins, coronary sinus (blood vessel), right atrium B. Fetal Circulation 
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