Fighting infections viral infection – video link http://www.youtube.com/watch?v=Rp j0emEGShQ&feature=related

White Blood Cells!!

The scientific name for white blood cells is leukocytes They have a short life cycle, living from a few days to a few weeks. A drop of blood can contain anywhere from 7,000 to 25,000 white blood cells at a time.

white blood cells are continually on the lookout for signs of disease. When a germ does appear, the white blood cells have a variety of ways by which they can attack. The number of WBCs in the blood is often an indicator of disease.

White blood cells are capable of passing through the walls of capillaries (tiny blood vessels) in order to attack, kill and consume intruder germs.

TYPES OF WHITE BLOOD CELLS One type of white blood cell is called a B cell. These cells are responsible for making antibodies. Antibodies are made to connect with things called antigens that are found on the surfaces of bacteria

1. They make the appropriate antibody to fit ‘lock and key’ B cells will travel around in your blood looking for bacteria with antigens on them 1. They make the appropriate antibody to fit ‘lock and key’ 2. Once the antibodies are connected to the antigens, it allows the bacteria to be recognised by engulfing white blood cells (making antibodies) – optional video link http://www.gatewayscienceonline.co.uk/ctrl/science/login/login?ref=%2F ctrl%2Fscience%2Fpreview%2Fpreview%3Fcs%3D0%26c%3D7%26n ode%3Da370%26page%3D1&login=1

B cells are really cool because they remember how to make the antibodies they create. In this way, if you are infected by the same microbe again, your body already knows how to fight it!

(Immunity)- optional video link The faster your body responds to an invading microbe, the less ill you get and the faster you recover. Your immune system works because it remembers all past infections and how to fight them (Immunity)- optional video link http://www.gatewayscienceonline.co.uk/ctrl/science/login/login?ref=%2Fctrl %2Fscience%2Fpreview%2Fpreview%3Fcs%3D0%26c%3D7%26ct%3Db%2 6node%3Da370%26page%3D4&login=1

TYPES OF WHITE BLOOD CELLS A second type of white blood cell ‘eats’ or engulfs bacteria. They are called phagocytes Phagocytes are able to tell what’s foreign because of the antibody/antigen interaction Antibody response – video link http://www.youtube.com/watch?v=lrYlZJiuf18

TYPES OF WHITE BLOOD CELLS A third type of white blood cell makes chemicals called antitoxins. Remember: many bacteria and viruses release toxins into your blood that cause illness Antitoxins are chemicals your body makes to counteract the harmful toxins

Note: White blood cells are also called Leukocytes Three ways to fight an infection: Produce antibodies to antigens found on the surface of bacteria To engulf or eat the infecting microbes To produce anti-toxins to toxins produce by invading bacteria