Single red blood cell (erythrocyte) surrounded by platelets (thrombocytes), coloured scanning electron micrograph (SEM). Erythrocytes contain the iron rich protein haemoglobin which binds oxygen. Erythrocytes transport oxygen from the lungs to the rest of the body and also remove carbon dioxide from the body by transporting it to the lungs where it is exhaled. Thrombocytes are a component of blood made in the bone marrow. In their non-activated state they are disc shaped but when a blood vessel becomes damaged, it will send out a signal to thrombocytes who respond by travelling to the damaged area and transforming into their activated form as seen in most of the thrombocytes in this image. They change shape and form long tentacle-like protrusions that are sticky, which assists them in adhering to each other. This helps them to form a plug or clot to fix the damage at the site of a wound. Too many or too few platelets can result in a variety of health conditions and many diseases are