the heart

• What is myogenic?

  The heart having its own intrinsic heart beat/rhythm
• label the heart and describe where oxygenated and deoxygenated blood flows

  oxygenated blood flows through the left side whereas deoxygenated blood flows through the right side

  A) pulmonary artery

  B) vena cava

  C) aorta

  D) pulmonary vein

  E) semilunar

  F) tricuspid

  G) bicuspid

  H) septum

  I) thicker

  
• what is diastole?

  • relaxation
  • atria and ventricles fill with blood
  • volume and pressure of the blood in the heart builds
  • pressure in arteries is at a minimum
• what is systole?


  • contraction
  • atria and then ventricles contract
  • pressure inside the heart increases
  • blood is forced out
  • volume and pressure of blood is low at the end of systole
  • blood pressure in the arteries is at a maximum
• what are the sounds of heart beat caused by?

  blood pressure closing the valves of the heart
• why is having a myogenic heart rate advantageous?

  efficiency- prevents the body from wasting resources maintaining basic heart rate
• describe the wave of excitation in the heart

  1. wave of excitation begins in the SAN (sino-atrial) which causes atria to contract, initiating heart beat
  2. electrical activity from the SAN is picked up by the AVN. The AVN imposes a slight delay before stimulating the bundle of His, containing conducting tissue made up of purkyne fibres, which penetrate the septum through the ventricles
  3. bundle of His splits into two branches and conducts the wave to the apex of the heart
  4. at the apex the purkyne fibres spread through the ventricular walls. this triggers the contraction of the ventricles, beginning at the apex, for more efficient and complete emptying of the ventricles

  
• why is it important that the AVN imposes a slight delay before passing signals to the bundle of His?

  • to ensure the atria have stopped contracting before the ventricles do
  • to ensure the atria empty completely
• what is the equation for cardiac output?

  cardiac output = heart rate x stroke volume
• what's an ECG and how is it used?

  • electrocardiogram
  • measures electrical differences in the skin, resulting from heart contraction
  • electrodes stuck painlessly to clean skin
  • signal from each electrode is fed into a machine which produces an ECG
  • can be used to help recognise heart attacks, heart problems
• describe the abnormalities that show up in ECGs

  • tachycardia- heart beat is too rapid, over 100bpm (running on a TRACK). Normal when you exercise, are scared or have a fever. But can also be abnormal due to electrical problems in the heart
  • bradycardia- heart rate slows to below 60bpm. Can have this if you're fit, makes the heart beat slow and efficient. Severe bradycardia can be serious and may need an artificial pacemaker to keep the heart beating steadily
  • ectopic- extra heartbeats out of the normal rhythm. Can be normal if infrequent but serious when frequent
  • atrial fibrillation- rapid impulses generated in the atria. Contract very fast but not properly. So only some impulses passed to ventricle, which contract less often, so heart pumps blood less efficiently

  A) normal

  B) bradychardia

  C) tachycardia

  D) ectopic

  E) atrial fibrillation

  
• what is a PQRST complex?

  • P wave
  • QRS complex
  • T wave