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Cardiovascular System

Cardiovascular System. Biology 2122 Chapter 18. Heart Anatomy. Location : Mediastinum Coverings ( Pericardium ) Fibrous and Serous layers Serous (Parietal and Visceral = epicardium ) Heart Wall (Layers) Epicardium ; Myocardium; Endocardium. Chambers. Atria

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Cardiovascular System

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  1. Cardiovascular System Biology 2122 Chapter 18

  2. Heart Anatomy Location: Mediastinum Coverings (Pericardium) • Fibrous and Serous layers • Serous (Parietal and Visceral = epicardium) HeartWall (Layers) • Epicardium; Myocardium; Endocardium

  3. Chambers Atria • Pectinate muscles; auricles • Superior and Inferior Vena Cava • Right-side • Deoxygenated Blood • Coronary sinus/Pulmonary veins Ventricles • Trabeculaecarneae/Papillary muscles • Pulmonary Trunk • Aorta Circulation • Pulmonary vs. Systemic

  4. Coronary Circulation Arterial – Left Coronary Artery • Anterior Interventricular • “Left Anterior Descending” • Circumflex Arterial – Right Coronary Artery • Marginal artery • Posterior Interventricular artery Venous • Cardiac veins • Coronary sinus • Great, middle, small cardiac veins Angina pectoris and Myocardial Infarctions

  5. Heart Valves • Atrioventricular Valves • Prevents backflow – chordae tendineae • Tricuspid (right) • Mitral (left) • Semilunar Valves • Aortic • Semilunar • Stenosis • Heart Animation

  6. Microscopic - Cardiac Tissue Histology • Cardiac Tissue • Striated • Branching • Uninucleated • Intercalated discs • Gap junctions • Functional Syncytium • High in mitochondria

  7. Cardiac Tissue - Contraction • Autorhythmic Cells • Heart Contracts as a unit • Ion passage through gap junctions • Steady and rhythmical waves of depolarization • Depolarization • Longer absolute refractory periods • 250 ms • Similar to depolarization events in skeletal muscle • Differs in Ca++ release (SR)

  8. Intrinsic Conduction System Sets basic or normal rhythm • Autorhythmic Cells Sequence of Excitation • SA node (right atria) • “pacemaker” • Atrioventricular node • Above tricuspid valve • Atrioventrical bundle • “bundle of his” • Superior interventricular septum • Bundle branches 5. Purkinje fibers • Apex • Intrinsic Conduction System Animation

  9. Disorders 1. Arrhythmias 2. Fibrillation 3. Heart Block

  10. Extrinsic Innervation and Control • Autonomic Nervous System • Sympathetic Effects • Parasympathetic Effects • Cardiac centers • Medulla Oblongata • Cardioacceleratory Center • Sympathetic (T1-T5) • Innervate SA and AV nodes • Cardioinhibitory Center • Vagus Nerve • To SA and AV nodes

  11. Electrocardiogram EKG lead placements

  12. Electrocardiography • The Electrocardiogram (ECG) • Waves • P-Wave • Depolarization (Atrial contraction) • SA node • QRS • Ventricular depolarization • Ventricular contraction • T-Wave • Ventricular repolarization

  13. Electrocardiography P-Q Interval S-T Segment Q-T Interval

  14. Abnormal ECG Non-functional SA Node Heart Block – Some P-waves not conducted through (see more P-waves)

  15. Heart Sound • “Lub-Dub” • Lub • AV valve closure • Dub • SL valves snap shut • Ventricular relaxation • Heart Murmer

  16. Cardiac Cycle • Systole vs diastole • The cardiac cycleinvolves all events associated with blood flow through the heart during one complete heartbeat • Ventricular filling: Mid-Late Diastole • EDV (end diastole volume) • Ventricular Systole • ESV (end systolic volume) • Isovolumetric Relaxation– Early diastole

  17. Cardiac Cycle Cardiac Cycle Animation

  18. Cardiac Output CO is defined as the amount of blood pumped out by each ventricle in one minute. • calculated as the product of stroke volume and rate HR X SV = 5.25 L/min Stroke volume- volume of blood pumped out by one ventricle with each beat CO is variable • increases in response to special demands like exercise The difference between resting CO and maximal CO is called cardiac reserve. In trained athletes it is 7 times that of normal (35 L/min)

  19. Stroke Volume Regulation SV is the difference between EDV (blood in ventricle during diastole) and ESV (blood in ventricle during systole) Normal SV = 70 ml/beat Depends on the following factors • Preload (Frank-Starling Law) • Contractility • Afterload

  20. Regulation of Stroke Volume • Preload • Frank-Starling Law • Cardiac muscle cells stretched to optimal length before contraction • Contractility • Independent of stretch • Greater Ca++ influx • Increased leads to greater SV • Afterload • Back pressure on aortic and pulmonary valves • Overcome pressure for ventricles to be able to eject blood

  21. Regulation of Heart Rate • Autonomic Nervous System 2. Chemical Regulation • Hormones (Epinephrine and Thyroxine) • Ions • Calcium (Hypo- and Hypercalcemia) • Potassium (Hypo- and Hyperkalemia) • Disorders/Imbalances • Tachycardia and Bradycardia 2. Congestive Heart failure

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