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Learning Summary Content Communicable Diseases Pathogens are microorganisms such as viruses and bacteria that cause infectious diseases in animals and plants. Pathogens may be viruses, bacteria, protists or fungi. Pathogens depend on their host to provide the conditions and nutrients that they need to grow and reproduce. Bacteria and viruses may reproduce rapidly inside the body. Bacteria may produce toxins that damage tissues and make us feel ill. Viruses live and reproduce inside cells, causing cell damage. Diseases caused by viruses, bacteria, protists and fungi can spread between animals and plants. Pathogens can spread by direct contact, water or air. Viral Diseases Measles is a viral disease which causes symptoms of fever and a red rash. Measles is a serious illness that can be fatal if complications arise. Most young children are vaccinated against measles. The measles virus is spread by inhalation of droplets from sneezes and coughs. HIV initially causes a flu-like illness. Unless successfully controlled with antiretroviral drugs the HIV virus attacks the body s immune cells. The late stage of the HIV infection, known as AIDS, occurs when the body s immune system becomes so badly damaged it can no longer deal with other infections or cancers. HIV is spread by sexual contact or exchange of body fluids such as blood which occurs when drug users share needles. Tobacco mosaic virus (TMV) is a widespread plant pathogen affecting many species of plants including tomatoes. TMV gives a distinctive mosaic pattern of discolouration on the leaves which affects the growth of the plant due to lack of photosynthesis. Bacterial Diseases Salmonella food poisoning is spread by bacteria ingested in food, or on food prepared in unhygienic conditions. Poultry in the UK are vaccinated against salmonella to control the spread. Salmonella causes fever, abdominal cramps, vomiting and diarrhoea. Gonorrhoea is a sexually transmitted disease (STD) with symptoms of a thick yellow or green discharge from the vagina How many lessons is it? Approximately 8/10 lessons How will I be assessed? Completion of homework Completion of SAM learning tasks Milestone tasks A mid-module assessment of keywords and basic scientific skills An end of module test that covers the content of the lessons What homework will be set? Simple tasks at the end of every lesson

or penis and pain on urination. Gonorrhoea was easily treated with the antibiotic penicillin until many resistant strains appeared. Gonorrhoea is spread by sexual contact. The spread of gonorrhoea can be controlled by treatment of antibiotics or the use of a barrier method of contraception. Fungal and Protist Diseases Rose black spot is a fungal disease where purple or black spots develop on leaves, which often turn yellow and drop early. Rose black spot affects the growth of the plant as photosynthesis is reduced. Rose black spot is spread in the environment by water or wind. Rose black spot can be treated by using fungicides and/or removing and destroying the affected leaves. The pathogens that cause malaria are protists. The malaria protist has a life cycle that includes the mosquito. Malaria causes recurrent episodes of fever and can be fatal. The spread of malaria is controlled by preventing the vectors, mosquitos, from breeding and by using mosquito nets to avoid being bitten. Human Defence Systems The body has non-specific defence systems to protect against pathogens, including; the skin, the nose, the trachea and bronchi and the stomach. The immune system defends the body against disease. If a pathogen enters the body the immune system tries to destroy the pathogen. White blood cells help to defend against pathogens by phagocytosis, antibody production and antitoxin production. Vaccination, Antibiotics and Painkillers. Vaccination can prevent illness in an individual. The spread of pathogens can be prevented by immunising a large proportion of the population. Vaccination involves introducing small quantities of dead or inactive forms of a pathogen into the body to stimulate the white blood cells to produce antibodies. If the same pathogen enters the body following vaccination the white blood cells respond quickly to produce the correct antibodies preventing infection. Antibiotics can be used to treat disease. Antibiotics, such as penicillin, are medicines that help to cure bacterial disease by killing infective bacteria inside the body.

Specific bacteria should be treated with specific antibiotics. The use of antibiotics has greatly reduced deaths from infectious bacterial diseases. The emergence of bacterial strains resistant to antibiotics is of great concern. Antibiotics cannot kill viral pathogens. Painkillers and other medicines are used to treat the symptoms of disease but do not kill pathogens. It is difficult to develop drugs that kill viruses without also damaging the body s tissues. Discovery and Development of Drugs Traditionally drugs were extracted from plants and microorganisms. The heart drug digitalis originates from foxgloves. The painkiller aspirin originates from willow. Penicillin was discovered by Alexander Fleming from the penicillium mould. Most new drugs are synthesised by chemists in the pharmaceutical industry, but the starting point may still be a chemical extracted from a plant. New medical drugs have to be tested and trialled before being used to check that they are safe and effective. New drugs are extensively tested for toxicity, efficacy and dose. Preclinical testing is done in a laboratory using cells, tissues and live animals. Clinical trials use healthy volunteers and patients. Very low doses of the drug are given at the start of a clinical trial. If a drug is found to be safe, further clinical trials are carried out to find the optimum dose for the drug. In double blind trials, some patients are given a placebo. Homeostasis and Response Cells in the body can only survive within narrow physical and chemical limits. Cells require a constant temperature and ph as well as a constant supply of dissolved food and water. The body requires control systems that constantly monitor and adjust the composition of the blood and tissues. The control systems include; receptors which sense changes and effectors that bring about changes. Homeostasis is the regulation of the internal conditions of a cell or organism to maintain optimum conditions for function in response to internal and external changes. Homeostasis maintains optimal conditions for enzyme action and all cell functions. Homeostasis in the human body involves the control of blood glucose concentration, body temperature and water levels. Automatic control systems may involve nervous responses or chemical responses. All control systems include receptors, coordination centres and effectors. Receptors detect stimuli (changes in the environment) Coordination centres (brain, spinal cord and pancreas) receive and process information from receptors. Effectors (muscles and glands) bring about responses which restore optimum levels.

The Human Nervous System The nervous system enables humans to react to their surroundings and to coordinate their behaviour. Information from receptors passes along cells (neurons) as electrical impulses to the central nervous system (CNS). The central nervous system is made up of the brain and the spinal cord. The CNS coordinates the response of effectors which may be muscles contracting or glands secreting hormones. The nervous system pathway is as follows; stimulus, receptor, coordinator, effector, response. Reflex actions are automatic and rapid; they do not involve the conscious part of the brain. A reflex action involves sensory neurons, relay neurons and synapses. The Human Endocrine System The endocrine system is composed of glands which secret chemicals called hormones directly into the bloodstream. The blood carries hormones to a target organ where they produce an effect. Compared to the nervous system the effects of hormones are slower but act for longer. The pituitary gland in the brain is a master gland which secretes several hormones into the blood in response to body conditions. Hormones from the pituitary gland act on other glands to stimulate other hormones to be released to bring about effects. Control of Blood Glucose Concentration Blood glucose concentration is monitored and controlled by the pancreas. If blood glucose concentration is too high the pancreas produces the hormone insulin that causes glucose to move from the blood into the cells. In liver and muscle cells excess glucose is converted to glycogen for storage. Type 1 diabetes is a disorder in which the pancreas fails to produce sufficient insulin. Type 1 diabetes is characterised by uncontrolled high blood glucose levels and is normally treated with insulin injections. In Type 2 diabetes the body cells no longer respond to insulin produced by the pancreas. Type 2 diabetes is commonly treated by a carbohydrate controlled diet and an exercise regime. (Higher Tier) If blood glucose concentration is too low, the pancreas produces the hormone glucagon that causes glycogen to be converted into glucose and released into the blood. (Higher Tier) Glucagon interacts with insulin in a negative feedback cycle to control blood glucose levels in the body. Negative Feedback (Higher Tier) Adrenaline is produced by the adrenal glands in times of fear or stress. It increases the heart rate and boosts the delivery of oxygen and glucose to the brain and muscles preparing the body for flight or fight. Thyroxine from the thyroid gland stimulates the basal metabolic rate.

Key Facts Know: - To know what is meant by the term pathogen and be able to give examples. - To know that measles, HIV and tobacco mosaic virus are caused by viruses. - To know that salmonella and gonorrhoea are caused by bacteria. - To know the symptoms of infection from salmonella bacteria. - To know that rose black spot is a fungal disease that affects plants. - To be able to explain the effect of rose black spot on plants. - To be able to describe the non-specific systems of the human body against pathogens. - To know the difference between antibiotics and painkillers. - To know where digitalis and aspirin originate from. - To know how the discovery of penicillin was made by Alexander Fleming. - To know what is meant by the term homeostasis - To be able to describe the principles of hormonal coordination and control by the human endocrine system. - To be able to identify the position of the pituitary gland, pancreas, thyroid, adrenal gland, ovary and testes on a diagram of the human body. Understand: - To be able to explain how diseases caused by viruses, bacteria, protists and fungi are spread in animals and plants. - To understand the effect of toxins released by pathogens on the body. - To be able to explain the vaccination process. Keyword Pathogen Microorganism Viruses Bacteria Toxin Immune system Protists Infectious disease Fungi Measles Symptoms Vaccination HIV Droplet infection Tobacco mosaic virus. Salmonella Antibiotic Penicillin Meaning A microorganism that causes disease. A microscopic living thing that requires a microscope to be seen. A microorganism that is smaller than a bacterium that cannot grow or reproduce unless inside a living cell. A single-celled prokaryotic organism. A poison produced by pathogens. The organs and processes of the body that provide resistance to infection and toxins. Any of a group of eukaryotic organisms belonging to the kingdom Protista. Any disease that can be passed from one organism to another. Any of a diverse group of eukaryotic organisms that live by decomposing and absorbing organic material on which they grow. An infection viral disease causing fever and a red rash that typically occurs during childhood. A physical or mental feature that indicates a disease. The process of injecting dead or inactive pathogenic material in a healthy person to develop immunity to a disease. A disease caused by a virus that damages the immune system and leads to development of AIDS. Infection spread by breathing in tiny droplets expelled when a carrier coughs or sneezes. A virus that affects plants. The disease causes a mosaic like discolouration of the leaves. A disease caused by a bacterium. Typically contracted by undercooked chicken or preparing food in unhygienic conditions. A type of drug used to treat disease caused by bacteria. The first antibiotic discovered by Alexander Fleming.

Key Facts - To understand how the spread of disease can be reduced or prevented. - To be able to describe the symptoms, prevention and treatment of measles. - To be able to describe the symptoms, prevention and treatment of HIV. - To be able to explain the effect of tobacco mosaic virus on plants. - To understand how salmonella food poisoning is spread and measures that can be taken to prevent its spread. - To understand how malaria spreads and how its spread can be prevented. - To be able to explain the role of the immune system in the defence against disease. - To be able to explain how vaccination will prevent illness in an individual. - To understand how large scale immunisation reduces the spread of pathogens. - To be able to explain the use of antibiotics and other medicines in treating disease. - To be understand the process of discovery and development of potential new medicines, including preclinical and clinical testing. - To be able to explain how blood glucose concentration, body temperature and water levels are controlled in the human body. - To be able to explain how the structure of the nervous system is adapted to its function. - To be able to explain how the various structures in the reflex arc relate to their function. - To understand how blood glucose concentration is monitored and controlled. - To be able to explain the difference between type 1 and type 2 diabetes and their treatment. - To be able to explain the roles of thyroxine and adrenaline and adrenaline in the body. Keyword Rose black spot Fungicides Malaria Vector Phagocytosis Antibodies Antitoxins Immunising White blood cells Painkiller Preclinical testing Clinical testing Digitalis Aspirin Toxicity Efficacy Dose Homeostasis Meaning A fungal disease where purple of black spots develop on leaves which often drop early. A chemical that destroys fungus. A life-threatening mosquito borne blood disease. An organism that transmits disease. The ingestion of bacteria or other material by white blood cells known as phagocytes. Proteins produced by white blood cells that attach to the antigens on the surface of a pathogen. Chemicals produced by white blood cells to neutralise the effects of toxins produced by pathogens. The process of becoming immune to a disease, usually by vaccination. A type of blood cell that defends the body against pathogens. A drug used to relieve pain. Trials of new medicines carried out on cells, tissues and live animals in the laboratory. The testing of new medicines on healthy and patient volunteers. A drug prepared from the leaves of foxgloves used to stimulate heart muscle. A synthetic compound used to relieve mild or chronic pain. A measure of ow toxic a substance is. A measure of how effective a drug is. The amount of a drug that should be taken. The regulation of the internal conditions of a cell or organism to maintain optimum conditions for function, in response to internal or external changes.

Key Facts Application/skills: - Evaluate the global use of vaccination in the prevention of disease. - To understand why the results of testing and trialling drugs are published only after scrutiny by peer review. - To be able to extract and interpret data from graphs, charts and tables about the functioning of the nervous system. - To be able to translate information about reaction times between numerical and graphical forms. - To plan and carry out an investigation into the effect of a factor on human reaction time. - To evaluate information around the relationship between obesity and diabetes and make recommendations taking into account social and ethical issues. - To be able to extract information and interpret data from graphs to show the effect of insulin on blood glucose levels in both people with and without diabetes. - To be able to interpret and explain simple diagrams of negative feedback control. Keyword Optimum Receptors Stimuli Coordination centre Effector Nervous system Central nervous system Reflex arc Sensory neurone Motor neurone Relay neurone Synapse Hormone Endocrine system Gland Glucose Meaning The best conditions. Cells that detect stimuli. Changes in the internal or external environment. Areas that receive and process information from receptors. Areas (usually muscles or glands) that bring about responses in the body. The network of nerve cells and fibres which transmit nerve impulses between parts of the body. The brain and the spinal cord. The parts of the nervous system which bring about a reflex action. They involve a sense organ, sensory neuron, relay neuron and motor neuron. Neurone that carries impulses from the sensory organs to the central nervous system. Neurones that carry impulses from the central nervous system to the effector organs. Neurones connecting sensory and motor neurons in a reflex arc. A gap between neurons. Chemicals produced in one area of the body of an organism that have an effect on the functioning of another area of the body. The glands that produce the hormones that control many aspects of the development and metabolism of the body, and the hormones they produce. An organ in the body that secretes chemicals such as hormones. Sugar.

Key Facts Keyword Insulin Diabetes Glucagon Glycogen Pituitary gland Thyroid Pancreas Adrenal gland Meaning Hormone involved in the control of blood sugar levels. A disease that affects the control of blood glucose concentration. A hormone used to convert glycogen back into glucose when blood sugar levels are low. The storage form of glucose. Endocrine master gland found in the brain that secretes a number of different hormones into the blood in response to different conditions to control other endocrine glands in the body. A large gland found in the neck that secretes hormones. A large gland behind the stomach which secretes insulin and glucagon to control blood glucose concentration. Endocrine glands that produce hormones including adrenaline and steroids.