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• Circulatory system


  Brings nutrients and oxygen (O) to the cells and removes waste products
• Main processes of the circulatory system

  Circulates blood between the heart and the lungs, as well as between the heart and the rest of the body
• Main components in the circulatory system

  • Heart
  • Blood vessels (veins, arteries, capillaries)
  • Blood
• The heart


  • Right side: pulmonary artery (to lungs), main veins (from body), right atrium
  • Left side: main artery (aorta) to the body, pulmonary veins (from lungs), left atrium, left ventricle, right ventricle
• Location and basic internal structure of the heart

  • Found just above the diaphragm in the thoracic cavity, between the two lungs, behind the breast bone
  • Centrally located with its tip slightly to the left
  • Hollow muscular pumping organ
  • Internally divided into a left and a right side, completely separated by a muscular wall
  • Consists of four chambers - two upper atria and two lower ventricles
  • Atria receive blood from veins entering the heart, ventricles pump blood into arteries to all parts of the body
  • Left ventricle has a thick muscular wall to pump blood at high pressure over a long distance, right ventricle has a thinner muscular wall to pump blood at low pressure over a short distance
  • One-way valves between the chambers keep the blood flowing in the right direction
• Circulation of blood through the body

  1. Carbon dioxide is removed and oxygen is absorbed by the lungs

  2. Deoxygenated blood is returned from the rest of the body by veins, enters the right atrium

  3. Right atrium contracts and forces the blood into the right ventricle

  4. Right ventricle contracts and forces blood from the heart through the pulmonary artery to the lungs

  5. Oxygenated blood returns from the lungs, enters the left atrium

  6. Left atrium contracts and forces the blood into the left ventricle

  7. Left ventricle contracts and forces the blood out of the aorta to the rest of the body

  8. Blood exchanges oxygen and nutrients and removes waste products in capillaries in the body
• Blood flows twice through the heart during a full circulation
• • Firstly, deoxygenated blood is pumped from the right side of the heart to the lungs where the blood absorbs oxygen
  • The oxygenated blood then returns to the left side of the heart from where it is pumped to the rest of the body to supply oxygen to the cells
• Blood vessels


  • Transport blood at high pressure away from the heart to all the different parts of the body
  • Have thick, muscular, elastic walls to withstand the high blood pressure
• Arteries


  • In the organs the arteries branch into many small, narrow ducts called capillaries
• Capillary blood vessels (capillaries)

  • The walls of capillary blood vessels are very thin, therefore cells get into close contact with the blood
  • Capillary blood vessels supply cells with oxygen and nutrients, and they remove waste products and carbon dioxide
• Veins


  • Transport blood at much lower pressure to the heart
  • Their walls are thinner and less muscular than those of arteries
  • The valves in veins allow the blood to flow in one direction and prevents it from flowing back
• Blood


  The fluid that moves in the blood vessels and transport substances throughout the body
• Constituents of blood


  • Blood plasma
  • Red blood cells
  • White blood cells
  • Platelets
• Blood plasma


  The liquid part of blood, mainly consisting of water and transporting nutrients, waste products and dissolved gases in solution
• Red blood corpuscles


  • Disc-shaped cells without nuclei, with a hollow in the centre giving them a biconcave shape
  • Formed in bone marrow
  • Main function is to carry oxygen to all parts of the body
• White blood corpuscles


  • Larger than red blood corpuscles, with an irregular shape and a clear nucleus
  • Main function is to destroy germs and defend the body against disease
• Platelets


  • Small fragments of cells that play a key role in blood clotting
  • Produced in the bone marrow
• High blood pressure


  A constant high pressure of blood in the arteries that forces the heart to work harder
• High blood pressure


  • Increases the workload of the heart, causes the heart to enlarge, and prevents the heart from pumping blood efficiently
  • Can cause a heart attack, kidney failure or a stroke
  • The high pressure against the artery walls can damage them
• Normal blood pressure varies throughout the day, rising when we are excited or nervous, or participate in some type of activity
• Heart attack


  Occurs when a stricture (narrowing) or blood clot develops in one of the blood vessels that supply the heart muscle with blood, blocking the blood flow and causing the heart to stop pumping
• A common symptom of a heart attack is a sharp pain in the centre of the chest that spreads to the jaw, back and left arm
• Causes of heart attacks include a fatty diet, lack of exercise, obesity, smoking and alcohol abuse, as well as inherited tendencies
• Stroke


  Occurs when the brain is deprived of oxygen, often due to a blockage or rupture in the blood vessels leading to the brain
• Symptoms of a stroke include feeling weak and confused, and becoming paralysed in certain parts of the body