HTHSCI 1H06 Lecture Notes - Lecture 3: Aortic Valve, Acetylcholine, Cardiac Muscle
8 Feb 2016
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Document Summary
Makes up 95% of the heart and is responsible for the pumping action. Fibres swirl diagonally around the heart in bundles; when the heart is pumping, the myocardium will wring the ventricles of the heart to help with the pumping of the blood. R & l bundle branches -> purkinje fibres. Inotropes are substances that influence the movement of calcium ions and therefore the heart contractile strength. A positive inotrope (epinephrine) will increase calcium inflow, and will increase the contractions: repolarization due to closure of calcium channels and potassium outflow when more potassium channels open. Refractory period is longer than the actual contraction. This is because the heart can"t pump blood if continuously contracted (heart would not have enough time to fill) if this did occur, blood flow would be drastically decreased. Illustrates the depolarization and repolarization of the atrium. P wave: contraction of the atrial fibres, action potential in the sa node, depolarization occurs before the contraction (atrial depolarization)
