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Published byMatilda Holt Modified over 9 years ago
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Trace the pathway of blood ( )through the body using the following terms: – Aorta – Right atrium – Left atrium – Right ventricle – Left ventricle – Lungs – Vena Cava – Venules – Arterioles – Capillaries – Body tissues – Pulmonary artery – Pulmonary vein
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The Heart
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Functions of the Heart Generating blood pressure Routing blood – Heart separates pulmonary and systemic circulations Ensuring one-way blood flow – Heart valves ensure one-way flow Regulating blood supply – Changes in contraction rate and force match blood delivery to changing metabolic needs
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Size, Shape, Location of Heart Size of a closed fist Shape – Apex: Blunt rounded point of cone – Base: Flat part at opposite of end of cone Located in thoracic cavity in mediastinum
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External Anatomy Four chambers – 2 atria – 2 ventricles Major veins – Superior& Inferior vena cava – Pulmonary veins Major arteries – Aorta – Pulmonary trunk
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External Anatomy
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External anatomy: anterior
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External anatomy: posterior
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Pericardium
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Heart Wall Three layers of tissue – Epicardium: (aka visceral pericardium) This serous membrane of smooth outer surface of heart – Myocardium: Middle layer composed of cardiac muscle cell and responsibility for heart contracting – Endocardium: Smooth inner surface of heart chambers
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Myocardium Cardiac muscle Fibrous skeleton of the heart – Consists of four dense connective tissue rings – Prevents overstretching of the valves – Serves as a point of insertion for cardiac muscle and as an electrical insulator.
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Cardiac Muscle Elongated, branching cells containing 1-2 centrally located nuclei Contains actin and myosin myofilaments Intercalated disks: Specialized cell-cell contact with Desmosomes and gap junctions Electrically, cardiac muscle behaves as single unit
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Histology of cardiac muscle tissue
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The chambers of the heart
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Systemic & Pulmonary Circulation
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Heart Valves Atrioventricular (AV) – Tricuspid – Bicuspid or mitral Semilunar – Aortic – Pulmonary Prevent blood from flowing back
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The AV valves
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The semilunar valves
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Location of Heart Valves
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Blood Flow Through Heart
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Intrinsic Conduction System Sinoatrial node/pacemaker – Crescent shaped node in right atrium – Enforces a contraction rate of 75 beats/min Atrioventricular node – Junction of atria and ventricles Atrioventricular bundle/bundle of His – In interventricular septum Purkinje fibers – Spread within the muscle of the ventricle walls
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The conduction system
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The excitation of the heart and ECG Systole contraction Diastole Relaxation Events of the Cardiac Cycle
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Normal Cardiac Cycle
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20-25 Cardiac Cycle
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Heart sounds Lup-dup, pause, lupdup, pause First heart sound or “lubb” – Closing of AV valves at beginning of ventricular systole Second heart sound or “dupp” – Closing of SL valves at beginning of ventricular diastole, lasts longer Third heart sound (occasional) – Caused by turbulent blood flow into ventricles and detected near end of first one-third of diastole
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Heart Mnemonics ValvesTRIPS BIAS TRIcuspid Pulmonary Semilunar BIcuspid Aortic Semilunar ValvesTRIPS, MI ASs (uses MItral instead of BIcuspid) TRIcuspid Pulmonary Semilunar MItral Aortic Semilunar Valves-Atriums"LAB RATs" Left Atrium: Bicuspid Right Atrium: Tricuspid Heart valves: closure sequence Many Things Are Possible": Mitral, Tricuspid, Aortic, Pulmonary Electrical SignalThe patient's family are all having Heart attacks, you must SAVe HIS KIN!" SA node ---> AV node ---> HIS (bundle of) --> PurKINje fibers Aorta BranchesKnow your ABC'S: Aortic arch gives rise to: Brachiocephalic trunk left Common Carotid left Subclavian
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Electrocardiogram P wave depolarization of the atria QRS complex depolarization of the ventricle T wave repolarization of ventricles
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The cardiac cycle: Ventricular filling
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The cardiac cycle: Ventricular systole
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The cardiac cycle: Isovolumetric relaxation
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Resources Heart Sounds & Cardiac Arrhythmias Live Cardiac Exam Video Anatomy Links Cardiac Cycle Cardiac Cycle Graphics Interactive Physiology Review
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