Blood

• Blood acts as a transport system
• Blood consists of plasma, platelets, white blood cells and red blood cells
• Plasma is the liquid component of blood
• Plasma is a pale yellow liquid that contains dissolved substances such as glucose, proteins, and salts
• Plasma helps to distribute heat throughout the body and to maintain homeostasis, or biological stability, including acid-base balance in the blood and body.
• Plasma carries red blood cells, white blood cells and platelets around the body
• Plasma carries water around the body
• Plasma carries digested products like glucose and amino acids from the gut to all the body cells
• Plasma carries carbon dioxide from the body cells to the lungs
• Plasma carries urea from the lungs to the kidneys ( where it's removed in the urine )
• Plasma carries hormones around the body - these act like chemical messengers which are sent into the blood
• Plasma carries antibodies around the body - these are proteins involved in the body's immune response
• Red blood cells have the job of carrying oxygen
• Red blood cells transport oxygen from the lungs to all the cells in the body
• The structure of a red blood cell is adapted to its function
• Red blood cells are small and have a biconcave disc shape to give a large surface area to volume ratio for absorbing and releasing oxygen
• Red blood cells contain haemoglobin, which is what gives blood its colour - it contains a lot of iron
• In the lungs, haemoglobin combines with oxygen to become oxyhaemoglobin and in body tissues the reverse happens to release oxygen to the cells
• Red blood cells don't have a nucleus - this frees up space for more haemoglobin, so they can carry more oxygen
• As red blood cells are small and very flexible, they can easily pass through the tiny capillaries
• Digested food products like glucose and amino acids need to be transported from the gut to all the body cells
• Carbon dioxide needs to be transported from the body cells to the lungs
• Urea needs to be transported from the liver to the kidneys - where it's removed in the urine 
• Hormones act like chemical messengers
• Antibodies are proteins involved in the bodies immune response