Physiology 206 Lecture 12 Outline of Last Lecture I. TetanyII. Motor neuronsIII. Motor unitsIV. Muscle fiber typesV. Muscle types Outline of Current Lecture I. Blood flow through heartII. DiastoleIII. SystoleIV. Frank Starling’s LawV. Heart ContractionCurrent Lecture2/12/14These 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 relaxedo Cardiac muscle relaxedo Heart expandso Reduces pressureo Heart fills with bloodo At the end, the heart begins to contracto Ventricle diastole: the lowest pressure in circulation- Systole: heart contractso Cardiac muscle contractso Raises pressureo Blood forced out of heart/into ventricles- Period of isovolumetric contraction (isometric contraction)o Ventricular muscle generates tensiono Increases pressureo Volume doesn’t changeo 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 Aortao 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 cellso If you stimulate one cell in the atria or ventricles, then that depolarization will spread through the chamber of the heart- SA nodeo Very leaky cellso Spontaneously depolarize about once per second and about 60 times per minuteo Transmits action potentials to neighboring
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