Leeches in medicine
Leeches belong to the phylum Annelida, class Hirudinea. They are exoparasites, meaning that they are located on the skin surface. Leeches feed on blood, they use suckers to attach on their hosts skin. They are dorso-ventrally flattened, have segmented bodies = each leech has a fixed number of segments – 34. 2 suckers are located at each end of the body (posterior and anterior). Leeches are hermaphrodites. Leaches are bilaterally symmetrical, with thick muscular segmented bodies. They can be found in water like rivers, lakes, or ponds. But they can’t live in salt water like beaches, oceans, and seas. Leeches vary in shape. They can be from 6mm to 20cm long. They have a coelom (body cavity) filled in with tissue. A clitellum used for reproduction (fertilized eggs are deposited in it). They have photoreceptor cells (sensory organ) that are used as simple eyes. As mentioned before leeches feed on blood of their hosts. Blood is a bodily fluid that we can find in the circulatory system. The important functions of blood are: to supply tissues with oxygen and nutrients (glucose, amino acids and fatty acids), removal of waste (carbon dioxide, lactic acid), blood clotting, fighting against bacteria and viruses (immune system). Blood is made up of: blood plasma (carries nutrients, proteins and hormones) red blood cells (carry oxygen to whole body), white blood cells (fight infection), platelets (blood clotting, prevents you from bleeding out). Even though leeches may seem as useless worms, the truth is very different. They have been used in medicine for centuries and still used nowadays. They are used in surgery mainly, to reattach body parts that have been cut off mainly because of accidents. Without leaches it would be very hard to reattach a cut off body part like a finger, toe, or ear because of the nerves and veins that are bleeding and swollen. Even if doctors try to sew them back in place, blood circulation to this part is halted because of...
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