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# Transportation in Animals and Plants ## Terms to Remember * **AURICLES:** the upper two chambers of the heart. * **VENTRICLES:** the lower two chambers of the heart. * **PULMONARY ARTERY:** carbon dioxide-rich blood from the right ventricle pumped through it to lungs for reoxygenation. * **PANCR...

# Transportation in Animals and Plants ## Terms to Remember * **AURICLES:** the upper two chambers of the heart. * **VENTRICLES:** the lower two chambers of the heart. * **PULMONARY ARTERY:** carbon dioxide-rich blood from the right ventricle pumped through it to lungs for reoxygenation. * **PANCREAS:** an organ in our body that releases insulin which controls the metabolism of sugar. * **TRANSLOCATION:** transport of food from leaves to the other parts of a plant. * **TRANSPIRATION:** loss of water from the leaves of plants. ## Transportation in Animals ### The Circulatory System in Humans In multicellular organisms, the number of materials that move in and out of the body is large. The distance over which these materials are to be transported is also large. Therefore these organisms require a specialized system to support various functions inside the body. Human beings have a developed circulatory system. The circulatory system carries the blood throughout the body and brings it back to the heart. The circulatory system in humans consists of: * **Blood** * **Blood Vessels** * **Heart** ### Blood * Blood is a liquid connective tissue. It is circulated throughout the body by the pumping action of the heart. * Blood is essentially an aqueous solution containing electrolytes, organic molecules, having suspended particles. * **Red Blood Cells (RBC; erythrocytes)** * **White Blood Cells (WBC; leukocytes)** * **Blood Platelets (thrombocytes)** * **Blood plasma:** The solution part of the blood (blood minus the particles). * **Blood serum:** When a protein called fibrinogen is removed from plasma, blood serum is obtained. #### Functions of Blood * Blood is the vehicle for metabolic communication between the organs of the body. * Blood transports nutrients from the small intestine to the liver and other organs. * It also transports waste products to the kidneys for excretion. * Blood transports oxygen from the lungs to the tissues and $CO_2$ generated during the respiratory metabolism to lungs for excretion. #### The Role of Blood in Oxygen Transport Respiration is a process in which oxygen gas (as air) is inhaled and carbon dioxide is exhaled. Blood transports these gaseous compounds through haemoglobin present in red blood cells (RBC). * Haemoglobin is a globular protein. * In the lungs, where oxygen is present in higher concentration, haemoglobin combines with oxygen to form oxyhemoglobin. * In tissues where oxygen content is low, oxyhaemoglobin dissociates and releases oxygen for use in respiration. ### Blood Vessels There are three types of blood vessels in our body. These are: * **Veins:** * Veins are tube-like blood vessels situated just under the skin. These can be easily seen as greenish-blue tubes on your hands and legs. * Veins carry carbon dioxide-rich blood from different parts of our body to the heart. * There are valves present in veins which allow blood to flow only in one direction. * **Arteries:** * Arteries carry oxygen-rich blood from the heart to all parts of the body. * Arteries are elastic, thick-walled and are deeper under the skin. * Blood flow through arteries is rapid and under pressure. * **Capillaries:** * There is a network of capillaries in our body. Capillaries are very thin. * Capillaries connect veins and arteries. #### Differences Between Artery, Vein and Capillary | Feature | Artery | Vein | Capillary | |---|---|---|---| | Thickness | Thick-walled | Thin-walled | Thin-walled | | Function | Carries oxygen-rich blood from the heart to other parts of the body. | Carries carbon dioxide-rich blood from different organs to the heart. | Involved in the exchange of food material, respiratory gasses, and body wastes. | | Location | Situated deep under the skin. | Situated just under the skin. | Occurs at the terminals of artery and vein. ### The Circulatory System The circulatory system carries the blood from the heart to different parts of the body and brings it back to the heart. It consists of heart, blood, and blood vessels (veins, arteries, and capillaries). * Blood is a liquid connective tissue. It contains red blood cells, white blood cells, blood platelets, and blood plasma. * Oxygen is carried by the haemoglobin present in red blood cells. * Veins carry blood from different parts of our body to the heart.. * Arteries carry blood from the heart to all parts of the body. * Capillaries connect veins and arteries. ### Heart The heart is the most sensitive part (organ) of our body. The heart in our body is located in the chest cavity, with its lower end slightly tilted towards the left. The size of our heart is nearly equal to that of our fist. It pumps blood to all parts of the body continuously. * The human heart has four chambers: * **Right and left auricles (for atrial)** * **Right and left ventricles** * **The upper two chambers are called atria (or auricles).** They have thin walls, and receive blood from different parts of the body. * **The lower two chambers are called ventricles.** Blood from ventricles is pumped out of the heart. * A muscular wall separates the left side of the heart from its right side. So, the blood cannot go from one auricle to another and one ventricle to another. Thus, this partition wall prevents mixing of oxygen-rich blood and carbon dioxide-rich blood. * The blood flows from the auricles to ventricles through valves. The valve that is between the right auricle and right ventricle is called tricuspid valve, and the valve that is between the left auricle and left ventricle is called bicuspid valve. ### Heart Beat The walls of the heart chambers are made of involuntary muscles. These muscles keep on working on their own and we have no control over them. The heart muscles expand and contract regularly and continuously throughout life. The rhythmic contraction followed by expansion (or relaxation) of the heart muscles constitute a heart beat. Since the contraction and expansion of the heart muscles is linked to the circulation of blood. Hence, the pumping of blood by the heart can be heard as a regular thumping sound. These are called heart beats. Doctors listen to the heart beat using a device called a stethoscope. From the nature and number of heartbeats in one minute, the doctor can find out the condition of your heart. ### Pulse and Pulse Rate Each time, the heart pumps the blood, it rushes through the arteries with a pressure. This pressure wave can be felt at various places on the body, viz, wrist, neck, temple. The number of pulse beats per minute is called pulse rate. For a normal resting person, the pulse rate usually lies between 72 to 80 pulse/beats per minute. Generally, pulse rate is measured by feeling the pulse at the inner wrist. Pulse rate increases with physical exercise. ## Transportation in Plants Plants have a well-developed transport system called vascular system. It consists of pipe-like vessels arranged from the tip of the roots to the tip of the leaves passing through the stem. There are two types of cells, commonly known as vessels in this system. These are: * **Xylem Vessels** * The xylem transports water and the dissolved minerals upwards from the roots. * Evaporation of water from the leaves during transpiration produces a pulling force causing water to move upwards. * **Phloem Vessels** * The phloem carries the food prepared by leaves downwards to the other parts of the plant. * In some plants, however, the material made in the roots is transported by phloem upwards to the leaves. ### Transport of Water and Minerals in Plants * Water is absorbed from the soil by the root hair. The root hair are in close contract with water surrounding the soil particles. Water moves from root hair to the root tissues and then to the xylem in the root. * The absorbed water then moves up the stem through the xylem. * Minerals are taken up by plants from the soil (as a solution in water) through root hair, root cortex, endodermis and reach the root xylem. * Then, the water containing minerals enters the interconnected xylem in the stem and finally into the leaf. ### Translocation of Food * Translocation is the transport of food from leaves (the site of food synthesis) to other parts of the plant. * The carbohydrates synthesized in leaves and hormones synthesized at the shoot and the root tips are transported to other parts of the plant through phloem. * Food molecules enter the phloem cells from mesophyll cells of the leaf. After entering phloem, the food molecules may move upwards or downwards in the plant. ## Excretion in Plants Unlike animals, plants have no special organs for removal of wastes. The waste products of respiration and photosynthesis are used as raw materials for each other. Oxygen gas produced as a by-product of photosynthesis is used up during respiration and carbon dioxide produced during respiration is used up during photosynthesis. Excretion is carried out in the plants in the following ways: * **The gaseous wastes, oxygen, carbon dioxide, and water vapor are released through stomata of leaves and lenticels of stems.** * **Some waste products collect in the leaves and bark of trees. When the leaves and bark are shed, the wastes are removed.** * **Some waste products are rendered harmless and then stored in the plant body as solid bodies.** Raphides, tannins, resins, gums, latex, rubber, and essential oils are some of the examples. ## Excretion in Humans The human body has specific organs for the removal of solid, liquid and gaseous body wastes. The main organs for excretion in humans are lungs, skin, large intestine, kidneys, anus and urethra. ### Liquid Waste In humans, excretion involves the removal of urea, sweat and undigested food. These body wastes are removed as follows: * **Solid Waste:** The solid waste generated in the body is removed as feces through the anus. * **Respiratory Waste:** The respiratory wastes – carbon dioxide and water vapor are carried by the blood to the lungs. The alveoli in the lungs remove carbon dioxide from the blood and is exhaled through the nose. * **Water, Salt, Urea, etc.:** The sweat glands under the skin remove water, salts, urea, etc., from the blood flowing through blood capillaries in the skin by diffusion. These wastes are then thrown out of the body through tiny pores on the skin. The liquid waste of the body is removed by the excretory (or urinary) system in the form of urine. ### The Excretory System in Humans The main organs of the human excretory system are: * **Kidneys (two)** * **Ureters (two)** * **Urinary bladder (one)** * **Urethra (one)** ### Kidneys Kidneys are the most important organ of this system. The function of the kidney is to filter the impure blood. Each kidney consists of millions of filters called nephrons. When blood laden with impurities passes through the kidney, nephrons filter the blood and remove urea and other salts from it. The yellowish filtered solution contains glucose, salts and nitrogen-containing compounds, such as urea. This yellowish solution containing the waste products called urine passes through the ureters and gets collected into the urinary bladder. The urine is then disposed off through the urethra.