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What is a myocardial infarction?Myocardial infarction is the medical name for a heart attack. Heart attacks occur when the flow of blood to the heart becomes blocked. They can cause tissue damage and can even be life-threatening.Cardiac cycle:The cardiac cycle consists of (1) the atria beating in unison (atrial______systole_____), (2) the contraction of both ventricles, (ventricular __systole______), and (3) the entire heart relaxes for a brief moment (___diastole____).3
During the cardiac cycle, pressure within the heart chambers rises and falls with the _systole_________ and ___diastole________ of atria and ventricles.When the atria fill, pressure in the atria is _higher___________ than that of the ventricles, which forces the ____A-V_______ valves open. Pressure inside atria rises further as they contract, forcing the remaining blood into the ventricles.When ventricles contract, pressure inside them _____increases________ sharply, causing __A-V____ valves to close and the _____pulmonary_____ and __aortic_______ valves to open.As the ventricles contract, ________papillary_______ muscles contract, pulling on ________chordae teninae___ and preventing the backflow of blood through the A-V valves.Heart sounds:Heart sounds are described as a "lubb-dupp" sound.The first sound (lubb) occurs as ________ventricles_________ contract and ______A-V_____valves are closing.The second sound (dupp) occurs as _______ventricles_________ relax and aortic and ____pulmonary_______ valves are closing.Cardiac Conduction system:Specialized cardiac muscle tissue conducts impulses throughout the myocardium and comprises the cardiac conduction system.A self-exciting mass of specialized cardiac muscle called the __________sinoatrial________ node (or pacemaker) is located on the posterior right atrium and generates the impulses for heart contraction. This node initiates impulses that spread throughout the myocardium and is self-exciting (-it does not require a signal from the nervous system).Impulses from the S-A node quickly spread throughout the atria and cause them to contract. Impulses also spread to the _______atrioventricular_______ (A-V) node. The A-V node rapidly sends a signal down the ____AV______ bundle and into the interventricular septum. These impulses rapidly spread through _____purkinje_______ fibers into the walls of the ventricles andcause the ventricles to contract. ECG/EKG:The first wave, the ____P______ wave, corresponds to the __________depolarization_________ of theatria.The _____QRS_____ complex corresponds to the ______depolarization__________ of ventricles and hides the ______repolarization____________ of atria.