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In this exhibit you learn about the different cells in our blood.
Your blood contains three different kinds of cells: red blood cells, white blood cells and platelets. Red blood cells carry oxygen around your body, white blood cells fight infection and platelets plug up wounds to prevent bleeding.
Red blood cells are shaped like a rounded disc with a dip on either side. They are full of a protein called haemoglobin. Haemoglobin is able to grab on to oxygen and take it around to the rest of the body. When haemoglobin has oxygen attached to it, we say that it is oxygenated and it is bright red, but when it is deoxygenated it is dark red. If you cut yourself, the blood will always be bright red because oxygen from the air wil oxygenate it. Blood taken from a vein with a syringe will be dark red because it doesn't come into contact with air.
To grab onto oxygen, haemoglobin needs iron. We get irn from our diet in foods such as green vegetables, red meat and seafood. If we don't get enough iron in our diet we become anaemic. This means that we don't have enough haemoglobin, so can't carry as much oxygen around. This makes us tired all the time. Blood-loss can also cause anaemia, until your body is able to replenish lost blood.
There are many different kinds of white blood cell that fight infection in various ways. Phagocytes are non-specific white blood cells which engulf germs and foreign objects then digest them. Specificity comes from the lymphocytes, of which there are two kinds: T-lymphocytes and B-lymphocytes. T-lymphocytes recognise specific germs or foreign objects, and co-ordinate the immune response, and B-lymphocytes release antibodies which immobilise and disable the germs or foreign objects.
When we damage a blood vessel, platelets prevent us from bleeding too much. They gather at the site of the damage and clot together, blocking the bleeding. This occurs because damaged cells in the blood vessels release signals, called clotting factors to the platelets. Some people suffer from haemophilia, an inherited disease where the people can't produce clotting factors so platelets do not clot. People with haemophilia bleed a lot when injured and bruise easily, and often need blood transfusion to replace lost blood. We can treat haemophilia by injecting people with clotting factors.
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Questions
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| 1 |
Your blood contains ________ different kinds of cells. |
| 2 |
What colour is oxygenated blood? |
| 3 |
Name two things that can cause anaemia. |
| 4 |
What kinds of cells release antibodies? |
| 5 |
How do platelets know when to form a clot? |
| 6 |
Do you know where most of our blood cells are made? |
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Activities
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| 1 |
Are you getting enough iron? Adolescent girls need 15 mg of iron a day and adolescent boys need 11 mg a day. Before puberty, you only need 8 mg a day. Keep a food diary for a week and work out how much iron you eat per day (read food packaging and check the Internet to find the iron content of foods). If you're not getting enough, what kinds of foods you should eat more of? |
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Some foods are "fortified with iron", which means that iron has been added to them. Some breakfast cereals have iron metal added to them, which we can't absorb so is actually useless to us. Take some breakfast cereal that says it is "fortified with iron" and grind it up, then add water to create a mush. Drop a magnet (the stronger the better) into the mush and stir for 10 min. Take the magnet out of the mush, and look at it with a magnifying glass. You should see specks of iron filings all over the magnet. Throw the mush in the bin and wash up. |
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