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KS4 Biology What is Energy Used For? 1 of 30 © Boardworks Ltd 2004 Contents What is Energy Used For? Processes that use energy Contracting muscles Building large molecules Thermoregulation Active transport Summary quiz 2 of 30 © Boardworks Ltd 2004 How does the body use energy? Respiration occurs in all body cells to release energy. What is this energy used for? This energy is used by the many processes that sustain life, such as… muscle contraction maintaining a steady body temperature building large molecules from smaller ones the active transport of substances within the body 3 of 30 © Boardworks Ltd 2004 Contents What is Energy Used For? Processes that use energy Contracting muscles Building large molecules Thermoregulation Active transport Summary quiz 4 of 30 © Boardworks Ltd 2004 Muscles use energy to contract Muscles work by contracting. When a muscle contracts it pulls a bone, creating lever. muscle bone Using the energy generated in muscle cells, muscle contraction alters the position of the bones. This means that work can be done, such as something can be lifted. muscle relaxed 5 of 30 energy muscle contracted © Boardworks Ltd 2004 Contents What is Energy Used For? Processes that use energy Contracting muscles Building large molecules Thermoregulation Active transport Summary quiz 6 of 30 © Boardworks Ltd 2004 The seven main food groups In order for the human body to maintain the metabolic processes in its cells, it must obtain nutrients from the seven food groups. What are these food groups? fats proteins minerals vitamins water fibre carbohydrates A balanced diet should be made up of food from all seven food groups. 7 of 30 © Boardworks Ltd 2004 Converting food into respiration materials The digestion of food produces many useful substances. digestion respiration energy useful raw materials The body uses the energy from respiration to turn these raw materials into useful substances. 8 of 30 © Boardworks Ltd 2004 Building a new protein molecule – step 1 An example of this use of energy is how the body builds new proteins from amino acids. Step 1 Proteins are eaten as part of our food (e.g. protein in eggs). albumin is the main protein in egg-whites 9 of 30 © Boardworks Ltd 2004 Building a new protein molecule – step 2 Step 2 These proteins are made of amino acid chains. The order of the amino acids is specific to the protein. amino acids 10 of 30 © Boardworks Ltd 2004 Building a new protein molecule – step 3 Step 3 This protein may not be the one that the body requires. Therefore, the digestive system uses protease enzymes to break up the amino acid chain. enzyme action 11 of 30 © Boardworks Ltd 2004 Building a new protein molecule – step 4 Step 4 This digestive process releases the individual amino acids. 12 of 30 © Boardworks Ltd 2004 Building a new protein molecule – step 5 Step 5 With the raw materials now free, the body can use energy from respiration to assemble them into new proteins. A new protein will have a different order of amino acids. energy respiration 13 of 30 new protein (old) © Boardworks Ltd 2004 Building a new protein molecule – step 6 Step 6 This new protein, and others like it, will now be used in different ways by the body. The energy from respiration makes this possible. protein moved to and then used elsewhere in the body new protein 14 of 30 © Boardworks Ltd 2004 Contents What is Energy Used For? Processes that use energy Contracting muscles Building large molecules Thermoregulation Active transport Summary quiz 15 of 30 © Boardworks Ltd 2004 Thermoregulation The conditions outside your body are constantly changing. One minute they can be hot, the next cold. Despite these changes, your body must be kept at a constant temperature of… o 37 C The body needs to remain at 37oC is because this is the temperature at which our enzymes work most effectively. 16 of 30 © Boardworks Ltd 2004 Temperature and enzymes Enzymes are temperature-sensitive chemicals that control many of the chemical reactions in the body. How are enzymes are affected when body temperature changes? colder Enzymes work slowly and the body is suffering. 17 of 30 37oC Enzymes work most effectively and body is fine. hotter Enzymes are heat-damaged and body can become ill. © Boardworks Ltd 2004 Sensing body temperature Body temperature is controlled by a region of the brain. As blood flows around the body, it passes through the thermoregulatory centre in the brain. rest of the body The brain senses body temperature by sensing the temperature of the blood. Once the brain knows what the body temperature is, it can act to keep it steady. How does the body react to hot and cold temperatures? 18 of 30 © Boardworks Ltd 2004 Feeling the heat When you feel too hot, how does your body react? You sweat, which helps to cool you down. Another cooling effect is that blood vessels in the skin expand. This means that more blood gets near the surface of the skin, which is why some people go red when they are too hot! The expansion of blood vessels uses some of the energy released by respiration. How do blood vessels use this energy? 19 of 30 © Boardworks Ltd 2004 How do blood vessels use energy? An artery wall is made of a thick inner layer of muscle. muscle cells blood outer wall The muscle cells are able to contract and relax using energy from respiration. How does the contraction and relaxation of these muscles affect the blood flow through this blood vessel? 20 of 30 © Boardworks Ltd 2004 Blood vessels and blood flow If the muscle lining a blood vessel contracts, the blood vessel becomes narrower and blood flow is constricted. blood flow constricted If the muscle lining a blood vessel relaxes, the blood vessel becomes wider and the blood flow increases. blood flow increased 21 of 30 © Boardworks Ltd 2004 Blood vessels in the skin How do blood vessels affect blood flow in the skin? skin surface blood vessels direction of blood flow The brain can cause the contraction and relaxation of the muscles within the walls of these blood vessels. This means that blood can be forced to take different routes through the blood vessels in the skin. What happens to blood flow when the body is too hot? 22 of 30 © Boardworks Ltd 2004 Increasing blood flow to the skin When the brain senses that the body is too hot, it acts to redirect the blood flow towards the surface of the skin. increased blood flow to the surface of the skin blood vessel widens blood vessel constricts The contraction and relaxation of these blood vessels forces more blood to flow within the surface of the skin. Energy from respiration is used to power the contraction of the muscle cells that allows this redirection to happen. How does this help to increase heat loss from the body? 23 of 30 © Boardworks Ltd 2004 Increasing heat loss from the skin When blood flows to the surface of the skin, it passes near the air surrounding the body. This air is much cooler than the temperature of the blood. air heat heat heat skin blood The heat within the blood escapes to the cool air. This causes body temperature to drop and you feel cooler. 24 of 30 © Boardworks Ltd 2004 Contents What is Energy Used For? Processes that use energy Contracting muscles Building large molecules Thermoregulation Active transport Summary quiz 25 of 30 © Boardworks Ltd 2004 Comparing active transport and diffusion Diffusion is the movement of substances down a concentration gradient from high to low concentration. high concentration diffusion active transport low concentration Sometimes substances move up a concentration gradient from low to high concentration. This process is called active transport and requires energy to make it happen. Where does the energy for active transport come from? 26 of 30 © Boardworks Ltd 2004 When does diffusion happen? diffusion Usually, substances move in and out of cells by diffusion from areas of high to low concentration. high concentration low concentration As an example, this particle could be an oxygen molecule in the lungs that is moving from an alveolus into a blood capillary. 27 of 30 © Boardworks Ltd 2004 When does active transport happen? active transport Sometimes, substances have to move in the opposite direction to the concentration gradient from areas of low to high concentration. This is active transport, which needs energy from respiration to take place. high concentration low concentration An example of active transport occurs can occur in the lungs when the oxygen supply is low but is still needed by the blood. 28 of 30 © Boardworks Ltd 2004 Contents What is Energy Used For? Processes that use energy Contracting muscles Building large molecules Thermoregulation Active transport Summary quiz 29 of 30 © Boardworks Ltd 2004 Multiple-choice quiz 30 of 30 © Boardworks Ltd 2004