ANATOMY&PHYSIOLOGY FOR NURSES

THE TISSUE CELL On the other hand, the cell needs a supply of energy for its activities and it will use some absorbed food materials as a fuel. The food is broken down and the energy stored in it is released and used by the cell. These destructive activities of the cell are called catabolism. Anabolism and catabolism make up the total activities of the cell.  or metabolism. The waste materials resulting from the catabolic processes are eliminated from the cell into the interstitial fluid, and thence carried away by the blood.  The blood transports the carbonic acid waste to the lungs where it is removed from the body as carbon dioxide. The other waste substances are eliminated, via the Kidneys, in the urine. The blood is also responsible for bringing to the cell its oxygen and other food requirements.                In describing the structure of the cell it is essential to relate its parts to its function. The protoplasm of the cell is composed of a centrally placed body, the nucleus, and the cytoplasm or remainder of the protoplasm, which surrounds the nucleus. CYTOPLASM.  This contains the following essential requirements: 1.Mitochondria, small rod-like structures which are closely connected with the catabolic, or respiratory, processes of the cell body. 2.Golgi apparatus. A canal-like structure lying next to the nucleus and involved in the secretory activities of the cell. 3.Ground cytoplasm.  A highly complex colloidal material in which the other structures are embeded. it is largely concerned with the anabolic, or synthetic, activities of the cell. 4. Centrosome. It is a minute dense part of the cytoplasm,mlying close to the nucleus. It plays ans important part during cell division. 5.Cell membrane. The cell boundary is no static envelope. Many important functions are connected with it, but in particular it acts as a selective sieve through which certain substances are allowed to pass into the cell, or which prevents other substances from gaining access to it. Thus it is most important in maintaining the correct chemical composition of protoplasm

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ANATOMY&PHYSIOLOGY FOR NURSES

THE BODY FLUIDS A about  70 per cent of the body is water in which are dissolved salts and other substances. This watery solution or fluid is partly inside the cells and partly outside, Two- thirds of the fluid is inside the cells, intra - cellular fluid, and is rich in protein and certain salts such as potassium. One- third of the fluid is in the spaces between the cells, the intersitial fluid, but about a quarter of it is in the blood vessels as the blood plasma. THE TISSUE CELL The cell is the smallest unit of living matter in the body capable of leading an independent existence. It is composed of a complex material called protoplasm, which contains water, inorganic salts and important organic substances-proteins, fats, carbohydrates and vitamins. Cells select from the interstitial fluid which surrounds them chemical substances such as amino-acids which the cell builds up into the very complicated substances, e.g proteins, which make up protoplasm. Thus a cell is a very active unit in which the nourishing food materials  eaten  by man are absorbed and assimilated. These materials may be used by the cell to synthesize new protoplasm, in which case the cell increase in size, that is, it grows.  The materials may also be used to replace worn- out parts of the cell. These constructive activities, growth and cell repair, are spoken of as the anabolic functions of the cell, or anabolism.                                                                                                            ..........

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