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Introduction |
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In unicellular organisms a single cell carries out all the life processes as the cell itself is the organism. In advanced forms like the few-celled algae, protozoa, sponges, etc., the size of the organism ensures that all the cells are not very far from each other. |
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Transport in Plants |
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The materials to be transported across the plant body are water, minerals and food. Apart from these nutrients, substances like the hormones also have to be transported. |
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Processes Involved in Transport |
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It is a physical process that involves the movement of solute particles from the region of their higher concentration to the region of their lower concentration. Transport of materials within the cell is by diffusion. The entry of carbon dioxide into the stomata is by diffusion. |
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Transpiration |
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Transpiration taking place through the stomata is called stomatal transpiration. The surface of the plant is covered by a thin layer of cuticle through which water vapour is lost during transpiration. This is called cuticular transpiration. |
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Ascent of Sap - Transport of Water |
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Plants absorb water from the soil through the roots. Thus, water has to be transported upwards to the other parts of the plant. This upward movement of water is called ascent of sap. It is called the sap as it contains many dissolved minerals. Ascent of sap involves root pressure and transpiration pull. |
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Transport of Minerals |
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Minerals are absorbed from the soil along with water as they are dissolved in water. They are taken up in the ionic form. |
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Transport of Food |
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Food is manufactured in the form of carbohydrates (sucrose) in the leaves. Thus, food is transported as sucrose along phloem. From the leaves the prepared food has to be transported to the roots, the younger top regions of the plant, the flowers and fruits. Thus, the food has to move in not only downward but also upward direction. |
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Transportation in Humanbeings |
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The transport system in animals is called the circulatory system. The materials are transported from one part of the body to another by a mass flow system which is the circulatory system. The animals, particularly the more advanced forms, have a higher metabolic rate. This means that they require more nutrients and oxygen at a faster rate. They also produce more wastes that have to be removed from the cells in less time. |
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Blood Circulatory System |
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The exchange of materials between the cells and the blood is done directly. There are few blood vessels but they are not extensive. The blood vessels are open-ended as they open into the common cavities called the haemocoel. |
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Components of Closed Circulatory System in Man |
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It is a red coloured, viscous, alkaline (pH about 7.4) fluid flowing through the body of higher animals. The adult human body consists of 5-6 litres of blood. |
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Components of Closed Circulatory System in Man - Contd. |
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They number 5 million per cubic mm in adult males and 4.5 million per cubic mm in adult females. Their number is higher in early infancy. The cells are composed of a network of fats and proteins between which are enmeshed numerous pigments called the haemoglobin which give the blood its colour. |
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Components of Closed Circulatory System in Man - Contd. |
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They are round biconvex cells that do not have a distinct nucleus. They are also called the thrombocytes. They number 250,000 to 400,000 per cubic mm of blood. Their life span is 8 to 14 days. They are involved in blood clotting. |
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Blood Groups |
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There are four types of blood among the humans. These are called the blood groups. The blood groups are classified based on the presence or absence of certain proteins and antibodies. |
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Blood Transfusion |
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In case of accidents, surgeries or prolonged illness, there can be a great loss of blood. In such cases, the body requires blood. Replacement of blood from external sources is called blood transfusion. However, the compatibility has to be checked before the transfusion occurs. |
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Blood Vessels |
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The human circulatory system is a closed circulatory system. The blood flows in closed vessels without coming in direct contact with the cells of the body. |
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Heart |
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The human heart is a muscular, cone-shaped, hollow organ about the size of a fist (about 12cm in length and 9cm in breadth). The heart is situated behind the sternum, between the lungs in the thoracic cavity. The heart is tilted slightly such that its apex is towards the left side. |
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Control of the Heart Function |
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The control of the heart function is by a set of muscles and is, therefore, called myogenic. |
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The Heart Beat |
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The heart beat results in electropotential differences spreading over the heart muscles. These follow a specific pattern. Any change in the pattern indicates an abnormality. The pattern can be recorded using an electrocardiograph. The recorded pattern is called the electrocardiogram (ECG). This is an important diagnostic tool in detecting any defect in the structure and functioning of the heart. |
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Blood Pressure |
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The rhythmic contractions and relaxation of the heart create high pressures required to keep the blood vessels from collapsing and also to ensure that all parts of the body get the supply of blood that is so vital to their survival and functioning. The pressure created during the ventricular systole is called the systolic pressure and is equal to that exerted by 120 mm column of Hg (mercury). |
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Circulation |
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The passage of blood throughout the body under the influence of the pressure exerted by the heart is called circulation. In mammals and birds the circulation is called double circulation. This is because the blood passes twice through the heart during one round of circulation. The other vertebrates have a single circulation. |
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Lymphatic System |
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At the capillary end of the arteries, the walls are only one-cell thick. The pressure in the arterial capillaries is also quite high. These leads the plasma to leak into the interstitial space. The interstitial space is the space between the cells of the tissue. |
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Diseases and Disorders of the Circulatory System |
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The condition in which a number of RBCs per cubic mm being less than normal is called anaemia. It may be due to poor diet or due to excessive bleeding. |
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Heart Attack |
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Heart attack is clinically Also called coronary thrombosis. The blood vessel supplying blood to the heart is blocked. This affects/stops the functioning of the heart resulting in heart attacks. |
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Importance of Studying Transportation |
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Transportation whether in plants or animals is the key to the efficient assimilation of the nutrients that the organisms synthesise, get from their environment or digest. The study of these processes helps us in many ways. |
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Summary |
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In lower organisms, there is no transport system as the cells are in touch with the surrounding medium. The transport is by the physical processes like diffusion, osmosis, etc. |
