Blood and circulation (B7)

a group of revision cards about the different blood groups and which bloods can be put with which bloods and the sirculatory system.

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  • Blood looks red, but up close it is cells floating in a pale yellow, watery liquid called plasma.
  • Plasma is mainly water and carries dissolved materials such as food molecules, hormones and waste products from cells. Plasma helps to pass heat around the body.
  • There are 3 types of cell that float in plasma;
  • Red Blood Cells - to transport oxygen
  • White Blood Cells - to fight infection
  • Platelets - clot blood at an injury site
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Red Blood Cells

  • They contain a protein called haemoglobin.
  • Haemoglobin binds oxygen as it passes through the lungs. oxygen is released into bodily tissues as blood flows around the body.
  • Red blood cells have no nucleus which means there is more room for oxygen.
  • The flat surface area means that oxygen can diffuse in anout quicker. The shape also means that they can squeeze through capillaries (capillaries are only one cell wide).
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White Blood Cells

  • White blood cells protect the body by fighting infection (sometimes known as nurse cells).
  • To destroy infections they produce antibodies and then engulf and digest the microorganism in a process called phagocytosis.
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  • Platelets are fragments of cells made up from the cytoplasm of larger cells.
  • When you cut yourself, platelets stick to the outside of he cut and clot your blood, preventing you from losing to much blood.
  • If you suffer a big loss of blood then you will need a blood transfusion.
  • Bags of blood have an anticoagulent in them to stop them from clotting up in the bag.
  • It is important that the bags have the blood type clearly printed on the front to prevent problems.
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The blood types

  • All cells have antigens on the outside of them, this is how White blood cells can detects them and produce the appropriate antibody to stick to the antigen.
  • Red blood cells have two different types of antigens, A and B. Depending on which antigens your red blood cells have, you can determine your blood type.

Blood Type                      Antigens                  Antibodies

A                                        A                             anti-B

B                                        B                             anti-A

AB                                  A and B                        none

O                                     neither                  anti-A and anti-B

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Blood Transfusions

  • It important when transferring blood that the recipient and the donor are the same blood type.
  • If they are not blood clots happen and this is fatal because it cannot circulate, leading to a stroke as blood can no longer get to the heart muscles.
  • People with the blood group AB can safely be given a transfusion of any blood type due to the lack of antibodies (universal recipient).
  • People with the blood group O can be given to anyone due to the lack of antigens (universal donors)
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How blood groups are inherited

  • Like many of your features, your blood group is determined by a single gene.
  • Allele IA - red blood cells have A antigens (Codominant)
  • Allele IB - red blood cells have B antigens (Codominant)
  • Allele IO - red blood cells have neither antigen A nor antigen B (Recessive)
  •  To predict a child's blood type you use a genetic cross diagram.
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very detailed and useful


Vair gud

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