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Papers > Science > Organisation of Cells into Tissues and Organs in Higher Eukaryotes
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Organisation of Cells into Tissues and Organs in Higher Eukaryotes |
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Cells are highly specialised for the different functions; through the organisation of these cells to form cooperative assemblies or tissues. There are over 200 different cells types. Each of these tissues comes together to form organs, which have their own specialized function. Cells are basic structural and functional unit of an organism; cells are the building blocks of life. The structure of cells (figure 1) is compatible for the formation of tissues. Eukaryotic cells have specialised plasma membranes that allow the cell adhesion through integral membrane proteins. In this essay the different tissue types are discussed and the cells of which they composed followed by the mechanisms of cell adhesion and the cell junction for support. Finally, how this organisation relates to the functioning of an organ. ... Structure of a eukaryotic cell In higher eukaryotes there are five main tissue types with a numerous diversity of cells; epithelial, connective, nerve, muscle and blood. Through description of these tissues it is possible to show the diversity of cellular modifications. Epithelial tissue Epithelial cells line all the surfaces of the body, internally and externally. ... The epithelial layers are composed of many different cell types ranging from columnar forms to cuboidal and squamous cells. ... Ciliated cells have minute projection called microvilli that increase the surface area of the cell for absorption. They also exhibit the ability to beat in synchrony to move substances such as mucus, secreted by specialised cells, along the epithelia sheet. Secretory cells can become associated to form glands, exocrine that secret products into ducts or exocrine that secrets hormones into the blood. ... It attaches the epithelial layer to the connective tissue beneath and is also found in association with other cells when in contact with connective tissue. Connective tissue This tissue provides a structural role, it provides a matrix that connects and binds the tissues and organs of the body giving support. ... Embedded in this are connective tissue cells, the most common of these fibroblasts. ... Connective tissue fulfils a variety of functions, it make up ligament, tendon and areola tissue that fills spaces between organs. Other cells include chrondoblasts; that produce cartilage, osteoblasts; which lay down bone and adipose cell; that store fat. Connective tissue also plays an immunological role the production of mast cells, from which active substances are released important in modulating inflammation, phagocytic cells that engulf foreign bodies and microorganisms. Plasma cells produce antibodies to combat the activity of harmful agents. The blood is considered connective tissue and the plasma the matrix, although not all components of this are from the cells but from other sources such as the liver. Erythrocytes are specially adapted cells that do not contain a nucleus, but haemoglobin to carry oxygen form the lungs to other cells in the body for cellular respiration. They are biconcave for effective gaseous exchange and are eventually broken down by phagocytic cells. Other cells include leukocytes primary used in immune response and defence of the body. Thrombocytes deal with clotting and once exposed to air form fibrin that is a sticky mesh to stop escaping cells causing a scab. ... The differentiated cells contain contractile proteins that generate forces necessary for cellular contraction, this cause movement in organs and the body as a whole. ... Skeletal muscle contains elongated muscle fibres of long cylindrical multinucleated cells with obvious striation. These cells are associated with large numbers of mitochondria, their contraction rapid but fatigue easily. ... Smooth muscle contains elongated, narrow uninucleate cells with no striation these are held together with collagen forming layers. ... This muscle is present in the tubular organs of the body, such as the blood vessels and is concerned with movement of materials throughout the body. Cardiac muscles only present in the heart and is composed of elongated, branched cells that are striated. These are held together by intercalated discs that allow cellular communication, causing the sequential contraction of the cells. ... Nerve tissue The nervous system is the most complex system within the body and is formed by a network of cells. |
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Paper Information |
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Title: Organisation of Cells into Tissues and Organs in Higher Eukaryotes
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