transport systems

• Components of blood


  • Plasma
  • Red blood cells
  • White blood cells
  • Platelets
• Plasma


  Pale yellow liquid which carries the blood cells suspended within it and many substances dissolved in it
• Red blood cells


  They do NOT have a nucleus and they contain haemoglobin which can bind to oxygen
• White blood cells


  They are part of the immune system and can produce antibodies
• Platelets


  Small fragments of cells that have no nucleus and produce substances that help the blood to clot
• Humans usually have about 5 litres of blood
• Blood is the transport medium of the body in humans and animals
• Substances dissolved in plasma


  • Carbon dioxide
  • Glucose
  • Amino acids
  • Antibodies
• Types of blood vessels


  • Arteries
  • Veins
  • Capillaries
• Arteries


  • Carry blood away from the heart
  • Have a thick layer of smooth and elastic fibres
  • Have a narrow space in the centre for blood to travel through
• Veins


  • Carry blood towards the heart
  • Have one-way valves to prevent backflow of blood
• Capillaries


  • Extremely small blood vessels where gas exchange and the delivery/collection of materials occurs
  • Red blood cells have to move through them in single file, slowing down the blood flow
• Blood flow through capillaries


  Substances move in and out of the bloodstream by diffusion
• Heart


  A muscular pump that keeps the blood moving around the body
• Chambers of the heart


  • Atria (upper chambers)
  • Ventricles (lower chambers)
• The heart's function is to pump blood around the body
• Coronary heart disease and heart attacks can be prevented through lifestyle changes
• Xylem tubes carry water and dissolved minerals from the roots to the leaves
• Transpiration


  The process by which water evaporates from the leaves and moves up through the xylem vessels
• Factors affecting transpiration rate


  • Higher wind speed
  • Higher temperature
  • Lower humidity
• Translocation


  The process of moving sugars produced in the leaves to other parts of the plant
• Phloem transports the sugars produced in the leaves to other parts of the plant