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03/05/2017 Biology (AQA) New Bridge Academy Science dept. The Nervous System 03/05/2017 The NERVOUS SYSTEM enables us to react to our surroundings. It consists mainly of the brain, the spinal chord, nerve cells (“neurones”) and receptors. Types of receptor: 1) Light receptors in the eyes 2) Sound receptors in the ears 3) Taste receptors on the tongue 4) Smell receptors in the nose 5) Touch, pressure and temperature receptors in the skin 6) Changes of position receptors in the ears (balance) Nervous Reactions 03/05/2017 When we react to a stimulus our bodies use the following pattern: Stimulus Receptor For example, consider a man and a camel: Coordinator Effector Response Oh No! What are the stimulus, receptor, coordinator, effector and response in this situation? Examples of reactions Stimulus Bright light Sour taste Losing balance Sit on a drawing pin Receptor (i.e. the thing that detects the stimulus) Effector (i.e. the thing that will do the reaction) 03/05/2017 Response (i.e. action taken) Types of nerve cell Nucleus Cell body 03/05/2017 Muscle strands (effector) Nerve cells (neurones) are elongated with branched endings to connect to many muscles fibres. 1) Motor neurone 2) Sensory neurone Impulse Impulse 3) Relay neurone Conscious actions 03/05/2017 A conscious action is one where the brain makes a considered response. Here’s what happens: 4) The brain 3) Here another sensory neurone decides to move carries the signal to the brain away the hand 5) This impulse is sent by MOTOR NEURONES to the hand muscles (the effectors) via the spinal chord… 2) The impulse is carried by SENSORY NEURONES to the spinal chord 1) Receptors in your skin detect a stimulus Stimulus 6) Which then moves the hand away Receptor Motor Neurone Sensory Neurone Effector Coordinator Response Reflex actions 03/05/2017 Sometimes conscious action is too slow to prevent harm, e.g… In situations like this the body bypasses the brain to produce a quicker response. Here’s how it works… Reflex actions 2. Sensory neurone 1. Receptor 03/05/2017 3. Relay neurone in the spinal chord 4. Motor neurone 5. Effector Synapses 03/05/2017 Neurones never ____ each other – there is a small gap between them called a _____. A signal is sent from one _______ to the next by a _______ transmitter across the synapse. These transmitters are then ________. Words – chemical, synapse, neurone, touch, destroyed Homeostasis 03/05/2017 Homeostasis means “controlling internal conditions”: Waste products that need to be removed + how CO2 Produced by respiration, removed via lungs Urea Produced by liver breaking down amino acids, removed by kidneys and transferred to bladder Internal conditions that need controlling + how Temperature Increased by shivering, lost by sweating Ion content Increased by eating, lost by sweating + urine Water content Increased by drinking, lost by sweating + urine Blood glucose Increased and decreased by hormones Fertility 03/05/2017 The amount of glucose in our blood is an example of a process controlled by hormones. Hormones are “chemical messengers”, produced by glands and tranposrted by blood. Another example of a process controlled by hormones is the menstrual cycle, where hormones can... 1) …stimulate the release of eggs 2) …inhibit the release of eggs In normal circumstances natural hormones are responsible for releasing the egg and for thickening the lining of the womb. These hormones are produced by the pituitary gland in the brain and in the ovaries. Fertility 03/05/2017 3 hormones are involved in the menstrual cycle: oestrogen, LH and FSH. Here’s how: Step 1: FSH produced by the pituitary gland causes both an egg to mature and the ovaries to start producing oestrogen Step 2: The rising levels of oestrogen cause the pituitary gland to stop producing FSH and produce LH instead Step 3: LH stimulates the release of the mature egg in the middle of the menstrual cycle Artificial fertility: 1) To INCREASE fertility FSH is given to stimulate maturation of eggs. 2) To DECREASE fertility oestrogen is given (“The Pill”) to inhibit FSH production stopping eggs from maturing. Balanced diet 03/05/2017 A balanced diet should contain fats, proteins and carbohydrates in roughly these amounts: Carbohydrates Fat Protein It should also contain water, vitamins, minerals and fibre. Poor diets 03/05/2017 If we don’t have a balanced diet we may suffer form a “deficiency symptom”: Lack of… Causes… Vitamin D Anaemia Protein Scurvy (bleeding gums and joints) Vitamin C Weak bones and teeth Vitamin A Wasting of body tissue Iron Rickets Calcium Poor night vision Metabolic Rate and health 03/05/2017 The rate at which our bodies carry out chemical reactions is called the “metabolic rate”. This rate varies with: • The amount of work we do • The amount of fat in our body • Inherited factors Condition Lack of exercise Fatty diets Warm weather Using cars instead of walking Playing XBox instead of football How this affects our health 03/05/2017 Conditions caused by increased weight Obesity is a condition caused by excess weight. This can also lead to the following diseases: Athiritis Heart disease What is it? What is it? What causes it? What causes it? Diabetes High blood pressure What is it? What is it? What causes it? What causes it? Heart disease 03/05/2017 Cholesterol 03/05/2017 Cholesterol is a fatty substance made in the liver from saturated fats in your food. The amount of it in your blood depends on your diet and inherited factors. Cholesterol is transported in the bloodstream attached to proteins. This combination is called a “lipoprotein”: Low density lipoproteins (LDL) High density lipoproteins (HDL) • “Bad” lipoproteins • “Good” lipoproteins • Carry cholesterol to cells • Carry cholesterol back to liver • High levels of LDLs cause fat to build up in the artery • Helps prevent cholesterol building up Restoring the balance 03/05/2017 Saturated fats (“bad fats”) increase cholesterol levels. Mono-unsaturated fats and polyunsaturates may help reduce cholesterol and restore the balance between LDLs and HDLs. Modern diets and health problems 03/05/2017 % obesity in the UK Drugs Why do people use illegal drugs? 03/05/2017 Cannabis: Pros and cons 03/05/2017 In January 2004 cannabis was changed from a class B drug to a class C drug. Some people think that Cannabis should be made legal. What are the pros and cons of cannabis? Pros: Cons: Smoking 03/05/2017 Cigarettes contain 3 harmful things: 1. NICOTINE, which is an ___________ drug that raises the heart beat, narrows the arteries and so causes ____ _____ _____. This leads to heart _________. 2. TAR, which coats the lining of the _______ making them less able to take in oxygen. It also contains carcinogens which cause ______________. 3. CARBON MONOXIDE, which is a _______ ____ which joins up with ____ blood cells making them incapable of transporting _____________ around the body. In pregnant women it can cause oxygen deprivation, leading to low birth ______. Words – high blood pressure, oxygen, red, addictive, disease, poisonous gas, lungs, cancer, mass Tobacco and Lung Cancer 03/05/2017 Smoking has existed in Western culture since the 16th Century. However, scientists only proved the link between it and various diseases shortly after the Second World War. Over 50 years I proved the link between smoking and lung cancer. I published my first findings in 1950, based on patients in London hospitals, and then studied 40,000 doctors and proved a link in a paper published in 1954. Sir Richard Doll, 1912-2005 Stopping smoking There are generally two methods of stopping smoking: “Cold turkey” – stopping completely with no help Nicotine Replacement Therapy – e.g. Patches, gum etc What are the advantages and disadvantages of each? 03/05/2017 Developing new drugs 03/05/2017 Before a new drug can be approved it has to go through a strict testing process. Consider the example of thalidomide: Date Event Mid 1950s Animal testing using thalidomide was undertaken. Tests showed that it was safe but the tests were “inadequate” – no tests were done on pregnant animals Late 1950s Thalidomide prescribed to pregnant mothers to help sleep and morning sickness problems Early 1960s Babies are born with birth defects and the drug was banned worldwide. Around 12,000 deformed Thalidomide babies born, 4,000 die in first year. Mid 1960s Tests show that Thalidomide can help leprosy sufferers and it is still used today for this purpose. Thalidomide children Mat Fraser, comedian and actor 03/05/2017 Tony Melendez, guitarist Drugs Research Project 03/05/2017 Explain and give examples for the following: 1) Why do people use legal drugs? 2) What are the drawbacks of legal drugs? 3) Alchohol is a legal drug. What does it do to the human body? 4) Why do people use illegal drugs? 5) What are the drawbacks of illegal drugs? What can they cause? 6) Choose one drug and discuss how it affects the human body Microbes 03/05/2017 Microbes are micro organisms that can cause diseases. They can enter the body in a number of ways: They can be breathed in through the mouth or nose …or other natural openings… They can enter through cuts or bites in the skin Disease 03/05/2017 A disease is any condition where the body isn’t working as it should. This could be caused by a malfunction in the body (as with diabetes) or it could be caused by a type of PATHOGEN (a microbe that causes disease): Bacteria Viruses • 1/1000th mm big • 1/1,000,000th mm big • Living cells (some are harmless) • Genetic info inside a protein coat • Grow very quickly • Not affected by antibiotics • Affected by antibiotics • Release poisons • Examples: food poisoning, tetanus, sore throats • Examples: colds, flu, polio, chicken pox Microbes: our defence against them 03/05/2017 Our bodies have four major defence mechanisms against invading microbes: The skin acts as a barrier If our skin is cut platelets seal the wound by clotting The breathing organs produce mucus to cover the lining of these organs and trap the microbes Our blood contains white blood cells Fighting disease If microbes enter our body they need to be neutralised or killed. This is done by WHITE BLOOD CELLS: White blood cells do 3 things: 1) They eat the microbe 2) They produce antibodies to neutralise the microbe 3) The produce antitoxins to neutralise the poisons produced by microbes 03/05/2017 Producing antibodies 03/05/2017 You’re going down Step 1: The white blood cell “sees” the pathogen (microbe) Step 2: The cell produces antibodies to “fit” the pathogen Step 3: The antibodies fit onto the pathogens and cause them to “clump” Step 4: The pathogens are “eaten” by the white blood cells Fighting disease NATURAL IMMUNITY This is when antibodies are produced by a person when needed or they are passed on by the mother during pregnancy. ARTIFICIAL IMMUNITY Can be done in two ways: 1) A vaccine with dead microbes is injected – the body is “tricked” into producing antibodies ready for the real thing. This is called PASSIVE IMMUNISATION 2) The antibodies are injected directly into the body – this is called ACTIVE IMMUNISATION. 03/05/2017 Using Antibiotics 03/05/2017 Antibiotics can be used to kill bacteria. However, there are two problems: 1) Overuse of antibiotics can lead to bacteria becoming resistant (e.g. the MRSA “superbug”). This means that antibiotics must be used sparingly. 2) Antibiotics have no effect on a virus, like the common cold. It is difficult to kill a virus without damaging body tissue. A virus is usually allowed to “run its course”. A smaller example… 03/05/2017 Although vaccinations and antibiotics are useful in the fight against pathogens, bacteria and virii can mutate to form a new, resistant “strain”: Bacteria 1) Variation – some strains of bacteria are resistant and some aren’t. 2) Competition – The non-resistant bacteria are killed by the penicillin. 3) Survival of the fittest – the resistant bacteria survive. Penicillin 4) Passing on of genes – the resistant bacteria reproduce and pass on their adaptations to their offspring. This is how the bird flu virus developed. Using Painkillers 03/05/2017 Painkillers are drugs used to relieve the symptoms of disease but without killin the pathogens, for example: Aspirin Paracetamol Ibuprofen The spread of infection 03/05/2017 Guten tag. In the mid-19th century I realised that many deaths in hospitals could be avoided by insisting on clean hands and equipment. As a result of my work deaths in my wards fell from 12% to 1%. Ignaz Semmelweiss 1818-1865 More people die due to infections from hospitals than on the roads in Britain. Hospitals have been trying to improve hygiene standards: Year Amount of hand wash solution used (litres per 1000 patient days) MRSA infections per 100 patients 1993 3.5 0.50 1995 6.9 0.48 1997 10.9 0.25 Vaccinations 03/05/2017 Some people argue that the MMR vaccine is a good idea, others think it is a bad idea. Briefly summarise each side of the argument: For Against MMR vaccine