Question | Answer |
Characteristics and Functions | The pump. Mediates between the systemic & pulmonary circuit. On average beats 75/min, 108,000/day. Average cardiac output is 5.25L/min. 4-6 liters blood total in body. |
Pulmonary circuit | Vessels that carry blood to & from the lungs. Right atria & ventricle. |
Systemic circuit | Vessels that transport blood to & from the body tissues. Left atria & ventricle. Thicker muscle walls. |
Heart orientation | Left of body midline. Posterior to sternum. In mediastinum. Lies on diaphragm. Base-posterior & superior surface of the heart. Apex-anterior & inferior & points to the left hip. |
Pericardium | Triple layered sack. Encloses heart. Fibrous Pericardium-attached to diaphragm. Double layered serous membrane: parietal layer (underside of fibrous), visceral layer (epicardium). Pericarditis=inflammation of pericardium. |
Pericaridal cavity | Space between parietal & visceral layers. Contains serous fluid. |
Pericardium functions | Prevents undesired movement. Prevents overfilling of heart. Reduces friction. |
Heart Wall | Epicardium-most superficial. Myocardium-bulk. cardiac muscle. deep to epicarium. myocardial infarctions occur in this layer. Endocardium-lines heart chambers. covers valves. deepest. |
External Anatomy | Atria-auricle=flap. Ventricles. Coronary sinus (posterior). Superior & inferior vena cava (Last 3 empty into R. Atrium). Pulmonary trunk. Pulmonary arteries. Pulmonary veins. Aorta. |
Fibrous Skeleton | Region of connective tissue located between the atria & ventricles. Functions-separates atria & ventricles, anchors heart valves, electrical insulation between atria & ventricles, framework for attachment of cardiac muscle tissue. |
Right Atrium | Receiving chamber for O2 poor blood from systemic circuit. Superior & inferior vena cava, coronary sinus. interatrial septum. PECTINATE MUSCLES (muscle in wall of atria). FOSSA OVALIS-foramen ovale during fetal circulation. Conducting nodes-SA & AV nodes. |
Right Ventricle | Pump of pulmonary circuit. Interventricular septum. Trabeculae carnae-muscular ridges. Papillary Muscles-anchor chordae tendinae. Chordae tendinae-prevent valves form everting during contraction. Pulmonary SEMILUNAR valve. |
Left Atrium | Posterior surface of the heart. Receives O2 rich blood from lungs. Left atrioventricular (AV) valve or bicuspid or mitral valve. |
Left Ventricle | Most muscular of the chambers-3x thicker then right ventricle. Forms the apex and inferior surface of the heart. Pump of the systemic circuit. Aortic semilunar valve. |
Valves | Can be either cuspid or semilunar. Composed of dense connective tissue. 2 or 3 cusps. Permit passage of blood in one direction. Prevent backflow of blood. |
Cardiac Muscle tissue | Fibers are short, branched, stiated, & contain 1-2 nuclei. Cells are joined by intercalcated discs. Gap junctions increase flow of electrolytes. Desmomsomes prevent cardiac muscle from pulling apart. More mitochondira & ATP than skeletal muscle. |
Cardiac cycle | Period of time from start of 1 heartbeat to initiation of next. All chambers experience alternate periods of contraction & relaxation. Systole: contraction of a heart chamber. Diastole: relaxation phase. Both atria contract together. Ventricles too. |
Conducting System | Specialized cardiac muscle cells carry impulses throughout the heart musculature. 1. Sinoatrial (SA) node 2. Atrioventricular (AV) node 3. Atrioventricular (AV)- Bundle of His 4. R & L bundle branches. 5. Purkinje fibers LABEL! |
Sinoatrial (SA) node | Pacemaker. Tells cells when to contract. |
Atrioventricular (AV) node | Slow conduction of impulse as it travels from atria to ventricles. Pauses so atria can contract before ventricles do. |
Atrioventricular(AV) bundle or Bundle of His | Conduct impulse into the interventricular septum |
Right and left bundle branches | Conduct impulse down interventricular septum to the apex of the heart. |
Purkinje fibers | Ensures that the heart contracts from apex and up the walls of the ventricles. |
Coronary Plexus | Sympathetic innervation: T1-T5. Increases the rate & force of heart contraction. Parasympathetic innervation: Medulla oblongata & vagus nerve 10. Decreases the rate of heart contraction. |
Heart Failure | Progressive weakening of heart. Weakened ventricles, failure of ventricles to empty completely, overfilling of ventricles, congestive heart failure-heart enlarges greatly, pumping efficiency progressively declines, pulmonary edema. Cause unknown. |
Myocardial Infarction | Heart attack. Caused by blockage of a coronary artery. Lack of blood flow to a region of the myocardium can cause heart muscle to die. Due to O2 depravation. |