Heart and blood vessels

• What are the four chambers of the heart?

  • left atrium, left ventricle
  • right atrium, right ventricle
• What are the three types of blood vessel?

  • arteries
  • veins
  • capillaries
• Blood flow through the heart

  1. Blood enters the heart through the atria

  2. Blood from the vena cava enters the right atrium

  3. Blood from the pulmonary veins enters the left atrium

  4. The atria fill, followed by the ventricles

  5. Blood is prevented from flowing back into the atria by heart valves

  6. Blood leaves the heart in the body's main artery - the aorta - from the left side, and the pulmonary artery, from the right

  7. Blood passes through the heart twice in one complete circulation of the body
• Right ventricle


  Pumps blood to the lungs where gas exchange takes place
• Left ventricle


  Pumps blood around the rest of the body
• Double circulatory system


  • The heart pumps blood through two circuits: the pulmonary circulation and the systemic circulation
  • The pulmonary circulation transports blood to the lungs
  • The systemic circulation transports oxygen and nutrients to the body, and carbon dioxide and other wastes away from cells
• Heartbeat


  • The heart has its own electrical system that regulates heartbeat
  • With every beat, there's an electrical signal that travels through the heart, causing it to contract and pump blood
  • If this doesn't happen properly, you could have an abnormal heart rhythm (or arrhythmia)
• Heartbeat process


  1. The SA node fires an electrical impulse that spreads through the walls of the right and left atria, causing the atria to contract

  2. The impulse travels to the AV node, and after a short pause, the pulses travel into the ventricles, causing them to contract
• Electrocardiogram (ECG)


  Used to monitor the electrical impulses from the heart
• Artificial pacemaker


  A small, battery-operated electronic device implanted in a person's chest that sends out regular, adjustable electrical impulses to produce normal contractions of the heart
• Structures in the heart diagram

  • Pumps oxygenated blood to the head and body
  • Receives deoxygenated blood from the head and body
  • Receives oxygenated blood from the lungs
  • Contains the pacemaker cells
  • Closes when the blood pressure in the aorta is greater than the blood pressure in the left ventricle
• The right ventricle pumps blood to the lungs
• The left ventricle pumps blood to the body
• Artificial pacemakers are electrical devices used to correct irregularities in heart rate
• Heart rate is controlled by cells located in the right atrium that act as a pacemaker
• Phloem


  A type of vascular tissue that transports sugars, amino acids, and hormones throughout the plant.
• Xylem

  A type of vascular tissue that transports water and minerals from roots to leaves, providing mechanical support and pressure maintenance.
• Translocation


  The process of transporting sugars and organic compounds from leaves to the rest of the plant through the phloem tissue.