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Year 9 Chemical Reactions – Acid and Alkalis - another attachment to email Acids and their properties Alkalis and their properties pH Indicators – Red Cabbage Word equations for reactions with acids - Alkalis – neutralisation - Metal - Metal carbonates Acids and their formulae Decomposition heat Copper carbonate Copper oxide + carbon dioxide Control and Coordination Label the eye and functions Draw and label a neurone Endocrine glands and the hormones they produce Infectious diseases and the pathogens that cause them The bodies response Human defence mechanisms CNS and the PNS 1 2 Protecting the Body - Defence Barriers The body has various defence mechanisms against pathogens. The first defence mechanisms / first lines of defence are those that protect the body as possible entry points. This protection is non-specific and aims to prevent any pathogens from entering the body. This type of defence takes place at the body surfaces. The body also has a second and third line of defence. The second line of defence which comes into play when pathogens succeed in entering the body is also non-specific. This is where cells in our immune system come into action. E.g. phagocytes. Non- specific means that they respond in the same way to all foreign material. The body’s third line of defence is specific and is mediated by lymphocytes (type of white blood cells). The First Line of Defence – Preventing entry A. The Skin Barrier a. The skin forms a tough outer barrier covering over the body. b. The outer layers of the skin contain keratin, and micro-organisms cannot penetrate it unless it is broken. c. The skin has its own population of harmless bacteria; their presence helps prevent invading pathogens from multiplying. d. Sebaceous gland in the skin secretes sebum. This sebum contains lipids that are broken down by the skin’s harmless bacteria to produce acids that inhibit the growth of some bacteria and fungi. e. If the skin is broken, the blood clotting mechanism quickly forms a seal across the wound to prevent the entry of pathogens. f. Other glands in the skin, the sweat glands secrete salt which also helps to inhibit bacteria. B. Mucous membranes Mucous membranes line the digestive, respiratory, reproductive and urinary tracts with a thick slimy mucous. This mucous membrane must be able to allow for the exchange of substances when needed and also protect against attack. This protection is aided with the presence of the antibody called IgA in the mucous. This reacts with potential pathogens preventing them from invading the surface. Fluids such as saliva, tears and nasal secretions also wash over the mucous membranes, these fluids contain lysozyme which, breaks down cell walls of some types of bacteria. 3 C. Cilia Cilia are minute hairs that project from the cells lining the respiratory surfaces of the nose and trachea and bronchial tubes. The cilia beat and sweep the mucus along, so that any particles breathed in and trapped by the mucous are transported to the nose opening or to the pharynx where they are coughed out or swallowed. D. Chemical barriers Chemical barriers are provided by conditions that make the surface of the body inhospitable for the potential pathogens. Example: in the alimentary canal, pathogens entering the body with food or drink are usually destroyed by the acid environment of the stomach or the alkaline environment in the small intestines. The enzyme lysozyme in tears dissolves the cell membrane of bacteria. E. Other body secretions Other body secretions also protect the body from invasion. Examples: There are populations of harmless micro-organism in the vagina. These act on cells shed from the walls of the vagina to create acid conditions which inhibit growth of some bacteria and fungi. Urine is a sterile, acid fluid. It flushes the ureters, bladder and urethra and helps prevent the growth of micro-organisms. Tears and saliva contain lysozymes that destroy bacteria. Milk contains lactoperoxidase and semen contains spermine – both compounds act against bacteria. The Second Line of Defence – Defence Adaptations Non- specific Responses Assume that your first line of defence has failed. Your skin has been cut and Clostridium tetani bacteria enter your body. Your second line of defence comes into action! Cells in your immune system act against the foreign material. 4 A. Inflammation Responses When the body tissue is damaged, such as by the invasion of a pathogen, the area becomes red, hot, swollen and painful. The blood circulation to that part is increased and the blood vessels dilate and become leaky. This helps to confine the pathogen while an increased number of white blood cells help destroy it. Dead cells and toxins can be removed quickly and repair of the tissue can begin. The inflammation response is mediated by chemicals such as histamine and prostaglandins released from damaged tissues. The release of histamines from the damaged tissue increases the permeability of the blood vessels, which allows the white blood cells to leave the blood vessels and move into the damaged tissue. The invading pathogen are killed and engulfed by the phagocytes (type of white blood cell). B. Phagocytosis Phagocytes are one type of white blood cells which form part of our bodies defence system. They can actively move from the blood to tissues where they are needed to fight infection. Phagocytes are the white blood cells that engulf and destroy micro-organisms and other foreign material that might enter the body. They do this in much the same way as an Amoeba engulfs its food. This process is called phagocytosis. Phagocytes are produced in the bone marrow and there are two types; neurophils and macrophages. Neurophils are the most common type of white blood cell and the macrophages are the largest. In acute inflammation (lasting hours or days) the main phagocytes are neurophills. In chronic inflammation (weeks or months) the main phagocytes are macrophages. Macrophages are particularly active against micro-organisms that can live inside the cells of the person they infect. As soon as a bacterium or other micro-organism is engulfed by a phagocyte, enzymes and other factors are released into the vacuole containing the bacterium and the bacterium is killed. A phagocyte that has already phagocytosed a bacterium can phagocytose more bacteria far more readily than a cell that has not, in this way many more bacteria are effectively removed and cannot cause damage to the host. How Phagocytes Work Question: How do phagocytes recognize and attach to a foreign body so that they can engulf them? 5 Answer: Blood proteins assist in this task. They are called complement proteins. Complement proteins assist in the second line of defence in a number of ways. - Some complement proteins stick to invading micro-organisms that become more readily identifiable by phagocytes as being foreign. Others stimulate the phagocytes to become more active. Some attract phagocytes to the site of the infection. Others destroy the membrane of the invading micro-organism. . C. The lymph System The lymphatic system comprises a system of vessels to return lymph to the blood circulatory system. Numerous thickened areas, called lymph nodes are spread along the system. These nodes contain large numbers of white blood cells that play a central role in the body’s second and third line of defence. At these lymph nodes or lymph glands white blood cells called lymphocytes are made and added to the lymph as it flows through. Lymph nodes also engulf and destroy bacteria and filter other foreign materials and cell debris circulating through them. Lymph nodes may become rather tender when there is an infection nearby. They are inflamed and enlarged by the bacteria and toxins they accumulate as they fight the invaders. D. Sealing off the pathogen When the body is unable to neutralize an antigen (foreign body), a particular type of chronic inflammation occurs involving both lymphocytes and macophages. The macrophages and lymphocytes completely surround a pathogen so that it is enclosed in a cyst. This cluster of cells is called a granuloma. The white cells involved die, so that the pathogen is isolated from its food supply and also dies. The granuloma consists of a central core of dead tissue which is surrounded first by macrophages, then lymphocytes and then fibroblasts which produce a tough outer wall. Granulomas are produced in tuberculosis and leprosy. The body’s immune response is its reaction to the invasion by foreign materials. 6 These foreign materials may be viruses, bacteria, toxins or other foreign proteins. Substances are identified as foreign by the body which then responds by trying to destroy them. Antigens are substances or molecules that trigger this immune response. If the previous two systems fail to destroy the pathogen then the body’s immune system comes into play. It depends on distinguishing between parts of the body and particles from the outside. It is important that phagocytes are able to make this distinction otherwise they would destroy body cells. Waves - another attachment to email Properties of waves - Wave diagram - V=fλ - Pitch - frequency Lenses Mirrors Electromagnetic spectrum Shocking Stuff – Electricity Series and Parallel circuits Resistance and Ohm’s Law (V = IxR) Circuit diagrams – symbols and fuses Electricity production and fossil fuels 7 Our Place in Space Big Bang theory Heliocentric and Geocentric models of the universe - Galileo - Newton Telescopes – including Hubble Life cycle of a star Hertzsprung-Russell diagrams Plate Tectonics Plates and plate boundaries Subduction zones Divergent zones – sea floor spreading Gwandaland Evidence for continental drift 8 Year 10 Atomic Theory Atomic structure Atomic number; mass number; electron configuration Periodic Table Reaction of metals and acids – activity series Ions – cations and anions Nuclear technology THE ATOM Atoms and Molecules An atom is the smallest part of an element which can take part in a chemical reaction. A molecule is the smallest particle of a substance capable of separate existence. Molecules are the basic units of compounds. Atoms An atom is made up of electrons, protons and neutrons. Protons and neutrons are in the nucleus of an atom. Protons are positively charged while neutrons have no charge. Electrons have a negative charge. The Periodic Table: The Periodic Table is divided into: Periods (rows) and Columns. Groups (1 to 0 (or 8) Metals and Non-metals The Groups 9 Each Group number represents the number of electrons in the outer shell, (excluding the transition metals). The number of electrons in the outer shell determines the reactivity of the element. Atomic Number The atomic number, Z, of an element is the number of protons in the nucleus of an atom of that element. Mass Number The mass number, A, is the number of protons plus neutrons in the nucleus of an atom of the element. The mass number – atomic number = the number of neutrons in the nucleus. In a neutral atom, the number of electrons equals the number of protons. The electron shells represent energy levels. The way the electrons fill theses shells is called the atoms ELECTRON CONFIGURATION. Electron Configuration. There are only ever TWO electrons in the first shell. Up to the first twenty elements each shell has a maximum of EIGHT electrons. The electron configuration for Hydrogen is 1 p The electron configuration for Helium is: 2 10 The electron configuration for Sodium is: 2,8,1 The Formation of Ions Atoms prefer to exist with full outer shells. To do this, atoms will either lose or gain electrons. An ION is an atom that has either lost or gained electrons. There are two types of ions: 1. Cation A cation is an atom that has LOST an electron(s). Cations have a POSITIVE charge. This positive charge comes from there being more protons (+ve) than there are electrons (-ve). For example: The sodium ion. The sodium atom has one electron in its’ outer shell. 1. Anions An anion is an element that has GAINED an electron(s). Electrons have a NEGATIVE charge. 11 This negative charge comes from there being more electrons (-ve) than there are protons (+ve). In terms of electrostatics, opposites attract. Therefore, positive ions (cations) will attract negative ions (anions). When this attraction occurs, ionic compounds form. Cars and Physics Newton's Three Laws of Motion Let us begin our explanation of how Newton changed our understanding of the Universe by enumerating his Three Laws of Motion. Newton's First Law of Motion: I. Every object in a state of uniform motion tends to remain in that state of motion unless an external force is applied to it. This we recognize as essentially Galileo's concept of inertia, and this is often termed simply the "Law of Inertia". Newton's Second Law of Motion: II. The relationship between an object's mass m, its acceleration a, and the applied force F is F = ma. Acceleration and force are vectors (as indicated by their symbols being displayed in slant bold font); in this law the direction of the force vector is the same as the direction of the acceleration vector. Newton's Third Law of Motion: 12 III. For every action there is an equal and opposite reaction. This law is exemplified by what happens if we step off a boat onto the bank of a lake: as we move in the direction of the shore, the boat tends to move in the opposite direction (leaving us facedown in the water, if we aren't careful!). Force is measured with a spring balance in Newtons 13