Circulatory System

• Circulatory system


  The system responsible for transporting blood, nutrients, oxygen, and other substances around the body
• Functions of the circulatory system

  • Transportation (blood cells, food molecules, hormones, CO2, urea)
  • Protection against diseases
• Components of the blood

  • Red blood cells
  • White blood cells (lymphocyte and phagocyte)
  • Platelets
  • Plasma
• Red blood cells


  • Specialised cells adapted for oxygen transport
  • Contains haemoglobin which is rich in iron and oxygen joins to it
  • Has a large biconcave shape which increases the surface area
  • No nucleus allowing more room for oxygen to be transported
• White blood cells


  Defence against disease
• Types of white blood cells

  • Lymphocyte
  • Phagocyte
• Lymphocyte


  A white blood cell that produces antibodies and causes microbes to clump together, has one large nucleus
• Phagocyte


  A type of white blood cell that engulfs microbes in a process called phagocytosis, has many small nuclei
• Platelets


  They convert fibrin into fibrinogen during blood clot when a cut is formed to produce a scab to prevent bleeding
• Plasma


  A straw coloured liquid which transports blood cells, food molecules, CO2 and urea
• Order of the circulatory system

  1. Pulmonary artery

  2. Aorta

  3. Hepatic portal vein

  4. Renal artery

  5. Renal vein

  6. Hepatic vein

  7. Vena cava

  8. Pulmonary vein

  9. Hepatic artery
• Pulmonary artery and vein


  Connected to the lungs
• Hepatic vein/artery and hepatic portal vein

  Connected to the liver
• Renal artery and vein

  Connected to the kidney
• Components of the heart

  • Vena cava
  • Right atrium
  • Right ventricle
  • Pulmonary artery
  • Left ventricle
  • Left atrium
  • Pulmonary vein
• Journey of blood through the body

  1. Vena cava

  2. Right atrium

  3. Right ventricle

  4. Pulmonary artery

  5. Lungs

  6. Pulmonary vein

  7. Left atrium

  8. Left ventricle

  9. Aorta

  10. Rest of the body
• Treatments for cardiovascular disease

  • Angioplasty and stents
  • Drugs
• Angioplasty and stents


  Angioplasty is a medical treatment where a 'balloon' widens and opens diseased arteries so that the mesh stents can be inserted into blood vessels
• Drugs used to treat cardiovascular disease

  • Aspirin
  • Statins
• Statins

  Help reduce cholesterol, prevent blockage in the artery and allow blood to flow more easily
• Structure of arteries

  • Thickest wall
  • Highest blood pressure
  • No valves
  • Muscles and Elastic fibers present to smooth out blood flow
  • Relatively small lumen
• Structure of veins


  • Thinner than artery
  • Less muscle and elastic fibres
  • Low blood pressure
  • Valves present-prevent backflow of blood
  • Relatively large lumen-prevent friction
• Structure of capillaries


  • One cell thick allows exchange between blood and body cells
  • Low blood pressure
  • No valves present
  • Very small lumen diameter
• Artery


  A blood vessel that carries blood under high pressure away from the heart (usually oxygenated blood)
• Vein


  A blood vessel that carries blood back to the heart (usually deoxygenated) with valves that maintain the direction of flow
• Capillary


  A very thin blood vessel through which the exchange of material between blood and cells takes place
• Double circulation


  The blood travels through the heart twice for each complete circuit of the body
• Effects of exercise


  • Strengthens the heart muscle
  • Increases cardiac output even when not exercising
  • Increased muscle contraction requiring energy from respiration
  • Increased cardiac output and blood flow to muscles to supply glucose and oxygen
• Ventricles are thicker than the atria because they are the chambers that pump the blood
• The left ventricle has a thicker muscular wall than the right ventricle because it pumps blood around the whole body, not just the lungs
• Valves


  • Prevent backflow
  • Ensure the heart works as a unidirectional pump
• Exercise


  Causes an increase in pulse rate