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S1 – Body Systems Summary Notes The Respiratory System – The Lungs LI 1 – We are learning about the role of the lungs Breathing is the process by which oxygen passes from the lungs to the blood stream and carbon dioxide passes from the blood stream to the lungs. They are therefore known as the organs of gas exchange. When we breathe the following process takes place: Air enters through mouth or nose. It passes down the WINDPIPE (trachea). The windpipe splits into two BRONCHI. The bronchi split, again and again, into BRONCHIOLES. The bronchioles end in tiny AIR SACS, millions in each lung. The exchange of oxygen and carbon dioxide between the air and the blood takes place in the air sacs or alveoli. The Respiratory System - Breathing LI 2 – We are learning about the differences between inhaling and exhaling. Inhale Exhale Ribs move up and out Ribs move in and down Diaphragm moves down Diaphragm moves up Chest cavity gets bigger Chest cavity gets smaller Air goes in Air goes out The Respiratory System – Vital Capacity and Tidal Volume LI 3 – We are learning about vital capacity and tidal volume. The volume of air that you move in and out of your lungs while breathing normally is called TIDAL VOLUME. This volume of air provides enough oxygen for a person who is resting. It is possible to inhale and exhale more forcefully - the maximum volume of air moved in and out of the lungs is called the VITAL CAPACITY. We can measure our vital capacity by taking a deep breath and breathing into a balloon then measuring the diameter of the balloon. The Respiratory System - Smoking LI 4 – We are learning to describe some of the health risks associated with smoking. Cigarettes contain approximately 7000 chemicals, many of them toxic. Some of them are shown below along with alternative uses of each chemical. There are many health risks associated with smoking: Chronic lung disease is a dangerous long-term effect of smoking. Two types of chronic lung disease are: – Chronic Bronchitis: this is where chemicals from tobacco build up in the lungs and make it difficult to breath. – Emphysema: this is where chemicals from tobacco destroy air sacs in the lungs and stop the lungs getting enough oxygen. Smoking affects more than just your health: The Digestive System – Food LI 5 – We are learning about the importance of a balanced diet. The three main food groups are carbohydrates, proteins and fats. Vitamins and minerals are also required to keep the body healthy, but are not strictly a food group. A balanced diet is needed to obtain all the nutrients we require. Food Type Examples Importance Carbohydrates (sugars and starches) Pasta, bread, potatoes Energy Protein Meat, fish, eggs Fats Dairy products e.g. milk and cheese Growth and repair of body tissues Insulation i.e. to keep heat in the body. Fats do not produce heat energy All of the cells in our body need food so that they can do their jobs and keep us functioning. Our bloodstream acts as a transportation system to carry food around the body to the places it is needed. Food must be broken down before it can enter the bloodstream. This process is called digestion. There are two types of digestion - mechanical (e.g. teeth) - chemical (e.g. digestive juices) The Digestive System – Food LI 6 – We are learning about the importance of digestion. Mechanical digestion occurs in the mouth where we chew our food in order to break it down into smaller pieces. We have different types of teeth for this purpose. Molar Canine Incisors Molars are used for grinding and crushing food Canines are used for tearing food or killing prey Incisors are used for biting Chemical Digestion As we chew our food a chemical called saliva is produced in the mouth. Saliva in our mouth mixes with food and helps break it down into substances that can be used by our bodies. Saliva also makes swallowing easier. The Digestive System – The Alimentary Canal LI 7 – We are learning to investigate the journey of food through the digestive system. The digestive system consists of: - the alimentary canal associated organs The alimentary canal is a long tube that carries food from the mouth all the way to the anus. The associated organs produce digestive juices that are added to the food as it passes along the alimentary canal. Food moves along the alimentary canal by the contraction of muscles behind the food and the relaxation of muscles in front of the food. The Digestive System - The Associated Organs LI 8 – We are investigating the role of the organs of the digestive system. The Stomach The stomach is a bit like a muscular bag that contracts and relaxes to mix food with the gastric juices it produces. This process is called churning. The Liver The liver produces bile. The gall bladder The gall bladder stores the bile. The Pancreas The pancreas produces enzymes. The Small Intestine Digested food passes through the wall of the small intestine into the bloodstream. The small intestine is lined with many finger-like projections. This increases the surface area of small intestine in contact with the digested food. This means that digested food can be quickly absorbed into the bloodstream The Large Intestine The large intestine absorbs excess water from digested food into the bloodstream. Once digestion is complete, the leftover materials pass through the large intestine into the rectum as faeces. Faeces are temporarily stored in the rectum before being expelled through the anus – at an appropriate time. The Reproductive System – The Reproductive Organs 9 – We are learning about the organs of the reproductive system. LI The male sex cells are called sperm. They are produced in the testes. The testes are held by the scrotum. The sperm tube carries sperm from the testes to the penis. The penis is the organ that carries sperm out of the body. Sperm Tube Testes Scrotum Penis The female sex cells are called eggs. They are produced in the ovaries. The oviduct carries the egg to the uterus (womb). The uterus is where a fertilised egg develops and grows into a baby. The vagina is the part of the female reproductive system that receives the sperm. Oviduct Ovary Uterus Cervix Vagina Male Reproductive System Part Testes Scrotum Sperm tube Penis Function Produces sperm Holds the testes Carries sperm to the penis Carries sperm out of the body Female Reproductive System Part Uterus Ovaries Egg tube (oviduct) Cervix Vagina Function Where the baby grows Produces eggs Carries egg to the uterus Opening to the vagina Receives the sperm The Reproductive System – The Sex Cells LI 10 – We are learning about sex cells. The male sex cell The female sex cell The sperm have a tail to swim to the egg Approximately 250 million sperm are released from the penis Only one sperm can fuse with the egg and fertilise it The Reproductive System – Fertilisation LI 11 – We are investigating the process of fertilisation Fertilisation The sperm from the testes are deposited into the vagina during sexual intercourse. The sperm then swim up the cervix and uterus and along the oviduct where it meets the egg. Fertilisation takes place in the oviduct. Fertilisation is the fusing together of the sperm nucleus and the egg nucleus. The fertilised egg divides into a ball of cells as it passes along the oviduct. When the embryo passes into the uterus it becomes attached to the uterus wall which has developed a spongy lining. It is attached by its umbilical cord to the placenta. The Reproductive System – Development of the Embryo LI 12 – We are learning about the development of the embryo. The developing embryo is connected to its mother by the umbilical cord. The baby’s blood passes through the cord to the placenta. In the placenta the mother’s blood and the baby’s blood come into close contact but do not mix. Food and oxygen pass from the mother’s blood into the baby’s blood and waste products pass from the baby’s blood to the mother’s blood. Usually harmful substances in the mother’s blood cannot reach the baby but there are some exceptions: German Measles is not really a serious illness in adults but it can have serious consequences for a developing foetus. If the virus that causes the illness passes through the placenta to the baby’s blood it can cause babies to be born blind, deaf and with other mental and physical problems. Nicotine, alcohol and other drugs can also pass to the baby’s blood.