The Blood (SQA National 5 Biology): Revision Note

Components of blood

• Blood is a vital transport medium in mammals, carrying essential substances around the body

• Mammalian blood consists of:

  • plasma

    • Over half of the volume of the blood is made up of plasma

  • red blood cells

    • The majority of the other half is made up of red blood cells

  • white blood cells

    • The remaining fraction consists of white blood cells and other components

• The role of blood is to transport

  • nutrients, such as glucose to respiring cells

  • oxygen to respiring cells

  • carbon dioxide to be excreted from the body