Heart

• The heart has 4 chambers: the left and right Atrium and Ventricles
• Valves prevent backflow of blood into the atria when the ventricles contract.
• The septum separates the two sides of the heart, preventing mixing of oxygenated and deoxygenated blood.
• Heart problems:

  Tachycardia - when the heart beats too fast

  bradycardia - when the heart beats too slow

  Atrial fibrillation - rapid and irregular contraction of the atria

  ventricular fibrillation - rapid and irregular contraction of the ventricles

  ectopic heartbeat - irregular beating of the heart
• Coronary artery disease is caused by fatty deposits on the walls of coronary arteries which can lead to blockages or ruptures causing myocardial infarction (heart attack)
• graph of just a normal heart rate

  A) atria

  B) ventricles

  C) ventricles repolarise

  
• Controlling heart rate:

  the heart initially is at diastole where it is at rest

  ->

  The SAN sends a nerve impulse which causes the atria to contract and push blood through the atrioventricular valves out into the relaxed ventricles

  ->

  the atrioventricular valves close (preventing backflow),the AVN delays the nerve impulse sent by the SAN then the ventricles recieve the impulse and constrict and force blood through the semilunar valves
• The Sinoatrial node (SAN) is located at the right atrium of the heart and is the pacemaker responsible for regular rhythm of the heart beat
• Valves in the heart?

  Atrioventricular valves, semilunar valves
• What is the name of the structure responsible for conducting electrical stimulation around the walls of the ventricle?

  The bundle of his
• What is the name of the fibres contained in the bundle of His?

  Purkinje fibers
• What is meant by the term atrial fibrillation?

  An abnormal heartbeat where rapid electrical impulses lead to rapid and incomplete contractions of the atria.
• What is meant by the term ectopic heartbeat?

  extra or skipped heart beats that are not apart of the normal rhythm