Science

Page 1 of 12

Science

By | October 2010
Page 1 of 12
The act of changing place or position by the entire body or by one or more of its parts is called movement. Movement is one of the characteristic features of living organisms. Study of movements is called kinesiology.sitThe Basic Types of Movements Movement involves 3 basic mechanisms. They are amoeboid, ciliary and muscular. Amoeboid movement is typically found in amoeba, a unicellular animal. Amoeba moves by producing pseudopodia, which are cytoplasm projections. This involves change in the shape of the cell body and streaming movement of cytoplasm into the pseudopodium. The movement due to pseudopodia in amoeba is termed as amoeboid movement. Amoeboid movement is characteristic of certain cells in other organisms. For example, the movement of white blood cells or leucocytes, in human blood. Amoeba moves about to obtain food or to avoid dangers or to escape from energy. Leucocytes like phagocytes or macrophages of the lymph, show amoeboid movements to engulf antigen or microbes and to immigrate in the circulatory fluid. Ciliary’s movement is the method by which ciliated protozoan like paramecium, move from plate to place in water medium. Paramecium uses cilia not only for moving from one plate to another (locomotion) also to drive water and food into their gullet. Cilia can perform a variety of functions:

1. In certain mollusks, cilia help to pass water currents over the gills 2. In echinoderms cilia helps to drive water through the water vascular system, (locomotion) 3. Cilia of the cells lining the respiratory tract of humans help to drive away the microbes and dust particles towards the nose or mouth 4. Cilia in the oviduct or fallopian tubes of human female transport ova Flagellum also helps in the movement in certain protozoan like euglena. Flagellum is a long, thread like cytoplasm projection. Flagellum in sperms also helps in the swimming movement. Muscular movement is the method used in most of the vertebrates, including man. Muscular movement is based...