What is in blood?
- Plasma fluid, which contains water, dissolved substances such glucose, hormones and waste products.
- Red blood cells bontaining haemoglobin to carry oxygen.
- White blood cells to fight infections, some make antibodies and some engluf and digest microorganisms.
- Platelets, which are fragments of cells that help to clot blood at a wound.
What are blood types and why are they important?
There are markers called Antigens on the surface of cells. If an antibody recognises a foreign antigen, it joins with it. Antibodies destroy cells in various ways:
If a person receiving a blood transfusion ( the recipient ) has antibodies to the antigens on the donors red blood cells:
- the red blood cells clump together.
- They block blood vesels and the person dies.
so to aviod clotting, the donor and recipients blood type must be matched.
How do we know which blood type is safe?
Remember the the recipients blood must not contain antibodies to the donors antigens.
blood type antigens antibodies this will clot ? can recieve blood?
A A Anti-B B A or O
B B Anti-A A B or O
AB AB None None AB,A,B,O
O Neither Anti-A and B A,B,AB O
People with type AB are called Universal recipients as they can receive any type.
People with O are called Universal donors as anyone can receive blood type O.
What is your heart like?
Your Heart pumps blood into arteries. Blood circulates:
heart--->artery--->smaller arteries--->capillaries--->small veins--->veins--->heart
In one circulation the blood flows through the heart twice. This is called the double circulation. We need it so that the blood:
- Gains oxygen and loses carbon dioxide in the circulation through the lungs.
- Loses oxygen and gains waste carbon dioxide as it circulates around the rest of the body.
Why are capillaries important?
Capillary walls are only one cell thick so:
- blood pressure can force water and dissolved substances from the blood out into the tissue. This forms tissue fluid.
- Substances such as oxygen. carbon dioxide, glucose and urea can diffuse between the blood and the tissues.