Anchor cusps of AV valves to papillary muscles Hold valve flaps in closed

Anchor cusps of av valves to papillary muscles hold

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Anchor cusps of AV valves to papillary muscles Hold valve flaps in closed position Prevent flaps from everting back into atria Semilunar (SL) valves - Prevent backflow from major arteries back into ventricles o Pulmonary semilunar valve Between right ventricle and pulmonary trunk o Aortic semilunar valve Between left ventricle and aorta As ventricles contract and intraventricular pressure rises , blood is pushed up against semilunar valves, forcing them open As ventricles relax and intraventricular pressure falls , blood flows back from arteries, filling the cusps of semilunar valves and forcing them to close Pathway of blood: Right side of heart (deoxygenated) Superior vena cava, inferior vena cava and coronary sinus right atrium tricuspid valve right ventricle pulmonary semilunar valve pulmonary trunk pulmonary arteries lungs for gas exchange (blood to be oxygenated) Left side of heart (oxygenated) (oxygen rich blood returns to the heart via) Four pulmonary veins left atrium mitral (bicuspid)valve left ventricle aortic semilunar valve aorta systemic circulation (to the rest of the body tissues)
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Coronary circulation - Functional blood supply to heart muscle itself o Shortest circulation in body Coronary arteries - Left and right arise from base of aorta and supply arterial blood to heart Left coronary artery - Supplies interventricular septum, anterior ventricular walls, left atrium and posterior wall of left ventricle o Two branches Anterior interventricular artery Circumflex artery Right coronary artery - Supplies right atrium and most of right ventricle o Two branches Right marginal artery Posterior interventricular artery Coronary veins - Cardiac veins o Collect blood from capillary beds - Coronary sinus o Empties into right atrium o Formed by merging cardiac veins Several anterior cardiac veins empty directly into right atrium anteriorly Cardiac Muscle Fibers o Cardiac muscle cells Striated short branched interconnected o One central nucleus o Numerous large mitochondria Intercalated discs - Connecting junctions between cardiac cells o Desmosomes Hold cells together Prevent cells from separating during contraction o Gap junctions Allows ions to pass from cell to cell Electrically couple adjacent cells
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Allows heart to be a functional syncytium, single coordinated unit Electrical Events of the Heart - Heart depolarizes and contracts without nervous system stimulation o Intrinsic cardiac conduction system Network of noncontractile (autorhythmic) cells Pacemaker cells Initiate and distribute impulses to coordinate depolarization and contraction of heart How Pacemaker cells make the heart beat Automaticity - Ability to fire an action potential by itself Action potential initiation by pacemaker cells o Cardiac pacemaker cells o Have unstable resting membrane potentials called pre-potentials
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  • Spring '14
  • Anastasia

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