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Control Of Heart Beat
 

Control Of Heart Beat

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    Control Of Heart Beat Control Of Heart Beat Presentation Transcript

    • Control of heart beat Please hand in your homework
    • What is wrong?
    • Starter question 1 square = 1mm
      • Cardiac muscle is myogenic
      • It does not need nerve impulses to contract
      • These contractions must be controlled so that cells work in unison
    • SAN
      • Sino atrial node
      • Small patch of muscle in right atrium wall
      • Pacemaker
      • Their contractions spread a wave of electrical activity in the atrial walls
      • Cardiac muscle responds, making the atria contract in time with the SAN
      • Both atria contract together
      • The excitation wave is briefly delayed by a bunch of fibres which do not conduct the electrical activity
      • This delay is to ensure that the ventricles contract after the atria
    • AVN
      • Atrio ventricular node
      • Small patch of conducting fibres high up in septum
      • Allows the electrical activity to spread slowly from the atria to the ventricles
      • Passes on to the purkyne tissue
    • Purkyne tissue
      • Fibres in septum
      • Cause contractions in ventricle walls from bottom up
      • Squeezing blood upwards
    • Diagram of heart showing SAN, AVN and purkyne tissue
    • Summary diagram
    • Blood vessels
      • We will examine and draw some prepared slides
      • Extension – if you would like to examine your own blood under the microscope you may do so, using a lancet
      • Homework to hand in next thurs– read about the 3 types of blood vessels – make a labelled diagram of each and describe the differences.