Biology (Circulatory system)

• How much blood is in the human body?

  Approximately 5 litres
• What is the yellowy liquid in the blood called?

  Plasma
• What is plasma mostly made from?

  Water
• What does plasma contain?

  • Dissolved food substances (glucose, amino acids, minerals)
  • Hormones
  • Antibodies
• What does plasma carry around the body?

  • Heat
  • Waste products (urea, carbon dioxide)
• What are the three main types of cells found in blood?

  • Red blood cells
  • White blood cells
  • Platelets
• What do red blood cells do?

  Carry oxygen around the body
• What do white blood cells do?

  Defend the body against invading microorganisms
• What are platelets?

  Tiny fragments of cells
• What do platelets do?

  Clot the blood if the skin is cut
• What are the two types of white blood cells?

  Phagocytes and lymphocytes
• What do phagocytes do?

  Engulf microbes
• What do lymphocytes do?

  Produce antibodies that lock onto invading microorganisms and destroy them
• What are these?

  Red blood cells

  
• What are these?

  White blood cells

  
• What are these?

  Platelets

  
• What are the adaptations of a red blood cell?

  • No nucleus
  • Biconcave disc
  • Haemoglobin
• How does having no nucleus benefit red blood cells?

  More space to carry oxygen
• How does the biconcave disc shape benefit red blood cells?

  It has a larger surface area to carry more oxygen
• How does containing haemoglobin benefit red blood cells?

  Contains iron that attaches to the oxygen
• How does blood travel around the body?

  Through blood vessels
• What are the three types of blood vessels?

  • Arteries
  • Capillaries
  • Veins
• Where do arteries take blood?

  Away from the heart and towards the organs
• What do arteries usually carry?

  Oxygenated blood
• What artery does not carry oxygenated blood?

  Pulmonary artery
• Why does the pulmonary artery not carry oxygenated blood?

  It goes from the heart to the lungs
• What are arteries made of?

  Muscle and elastic tissue
• What do arteries have thick walls?

  The blood in the artery is usually under high pressure - prevents them from bursting
• What is the make up of an artery?

  Walls = thick

  Lumen = small
• What happens to arteries as they travel away from the heart?

  They slowly branch of from one another and become smaller
• Where does the blood in the arteries get to?

  The blood reaches the capillaries
• How small are capillaries?

  Extremely small - only one cell thick (only just wide enough for red blood cells to pass through)
• What happens in the capillaries?

  Substances needed by our body cells pass out of the blood by diffusion and into the tissues
• What is dissolved through the capillaries?

  Oxygen and dissolved food
• What substances diffuse in the other direction (into the blood)?

  Waste substances produced by the cells - urea, carbon dioxide
• How quickly does diffusion through the capillaries occur?

  Rapidly - as the walls are one cell thick so the distance involved is short
• How many capillaries are in the body?

  Approximately 300 million
• How does having many capillaries in the body benefit us?

  Not one cell in our body is more than 0.1mm away from a capillary bringing it oxygen and food
• Where do veins take the blood?

  Collects the blood from the capillaries and carry it to the heart
• What happens to veins as they get closer to the heart?

  They slowly join together and get bigger