Physiology 206 Lecture 12 Outline of Last Lecture I Tetany II Motor neurons III Motor units IV Muscle fiber types V Muscle types Outline of Current Lecture I Blood flow through heart II Diastole III Systole IV Frank Starling s Law V Heart Contraction Current Lecture 2 12 14 These notes represent a detailed interpretation of the professor s lecture GradeBuddy is best used as a supplement to your own notes not as a substitute Fluids flow downhill from pressure Diastole heart is relaxed o Cardiac muscle relaxed o Heart expands o Reduces pressure o Heart fills with blood o At the end the heart begins to contract o Ventricle diastole the lowest pressure in circulation Systole heart contracts o Cardiac muscle contracts o Raises pressure o Blood forced out of heart into ventricles Period of isovolumetric contraction isometric contraction o Ventricular muscle generates tension o Increases pressure o Volume doesn t change o From the time that the ventricle contracts until the pressure in the aorta is greater 80mmHg o Shortening of cardiac muscles End diastole about 125 mL of blood End systole about 50mL of blood About 75mL of blood leaves the heart per heart beat Cardiac output about 5L per minutes Frank Starling s Law Law of the Aorta o Volume of blood the heart will eject will be equal to the volume that enters the heart What makes the heart contract o When an action potential stimulates cells o If you stimulate one cell in the atria or ventricles then that depolarization will spread through the chamber of the heart SA node o Very leaky cells o o Spontaneously depolarize about once per second and about 60 times per minute Transmits action potentials to neighboring cells
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