1. The nervous system

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2 1. The nervous system Our brain, spinal cord and nerves make up your central nervous system. Nerve fibres are made from lots of nerve cells, called neurones. There are three types of neurone: which take impulses from the sensor. which carry impulses to the brain. Motor neurones which take impulses to the muscles or glands, the effectors. Light, sound, pressure and temperature are all types of. They are picked up by that are found on our sense organs. A spinal reflex action is quick and automatic. It does not use the, it only uses the three neurones. brain receptors relay neurones sensory neurones stimuli 2. Drugs and their effects on the CNS alter the way our body works. Some drugs are taken for medical reasons but some are taken for pleasure. Drugs taken for pleasure are called drugs, such as, caffeine and tobacco. Other recreational drugs are illegal, such as cannabis or ecstasy. Drugs change the chemical processes in your body and can lead to. Alcohol has many affects on the body. It can make you more, slow your reaction times, make you feel drowsy, vomit or lead to unconsciousness. addiction alcohol drugs recreational relaxed

3 3. Smoking and tobacco Tobacco contains cancer forming chemicals called. Tobacco smoke contains substances such as tar, nicotine and carbon monoxide. Nicotine is the substance in tobacco smoke. in cigarette smoke takes the place of oxygen in the blood. This is why it is very dangerous for women to smoke during. It can lead to the baby having a low birth mass. People try many ways to give up smoking including hypnotism, patches and gradually reducing the amount they smoke. addictive carbon monoxide carcinogens nicotine pregnancy 4.Drug abuse is when drugs are used for the wrong reasons or used when they are not needed. Some drugs are legal but others are illegal. Heroin and Cocaine are examples of drugs. They are classified as A drugs. Cannabis is called a because some people think it leads onto taking more dangerous drugs. drugs are classified as A,B and C. Drug abuse can cause mental problems such as anxiety and hallucinations. It can also cause physical problems like insomnia and nausea. Some illegal drugs have medical benefits, for example cannabis can reduce the of multiple sclerosis. drug abuse gateway drug hard illegal symptoms

4 5. Hormones are chemical messengers. They are secreted by found around the body. They travel through the to organs where they control important processes. The system of glands and hormones is called the endocrine system. It is controlled by the which sends hormones to the gland to control other organs. Organs controlled by hormones include the testes and ovaries. bloodstream brain glands hormones pituitary 6. Controlling our internal environment Your body tries to keep a steady internal of 37 C. This is the temperature at which work best. is a source of energy for cells. The pancreas monitors the level of glucose in the blood. Your control the amount of water in your blood. They are controlled by ADH (anti-diuretic hormone). Salt contains sodium and chloride ions. They are needed to help your body work properly. Levels of sodium and ions are controlled by the kidneys. chloride enzymes glucose kidneys temperature

5 7. Menstruation The menstrual cycle involves the release of an egg from an ovary. is the hormone that controls the production of a protective covering around the egg (follicle). is the hormone that triggers ovulation. stimulates the uterus to repair the lining lost in the previous menstruation. pills contain oestrogen which stops the eggs from being matured by the ovaries. This means that fertilisation cannot happen. FSH production is stimulated by drugs. This in turn makes the ovaries release and egg. contraceptive fertility FSH LH oestrogen 8.Food and health are the chemicals that are in your food. Having the correct amount of each nutrient in your food is called a. If your diet is not balanced you might suffer from because you are not getting the nutrients you need. or fast foods contain substances that have been added to improve taste or colour or to stop them from going bad. Such substances include salt, sugar and saturated fats. Vitamins and are important to keep your body working properly. balanced diet malnutrition minerals nutrients processed

6 8. Metabolism reactions in your body provide you with the energy. The warmer it is the less energy you need to keep warm. This means you can eat less. The speed at which you use up energy is called your rate. Your resting metabolic rate provides energy so that you, digest food and so that you heart will keep beating. Your metabolic rate is higher: the more you the more muscle you have the you are. When you have finished exercising your metabolic rate remains high for a little while after. chemical exercise metabolic respire younger 9. Cholesterol Cholesterol is a type of fat made by the. It is carried around the body in the, attached to a protein. Some cholesterol is good cholesterol (HDL) and some is bad cholesterol (LDL). LDL deposits fats in your arteries. This can lead to heart attacks and strokes. High cholesterol in the blood can be inherited but it can also be caused by a diet high in fats. The amount of bad cholesterol can be reduced by eating fats. HDL stops bad cholesterol from building up in your arteries. Drugs, such as can be taken to lower the amount of cholesterol your liver produces. bloodstream liver polyunsaturated saturated statins

7 10. Diet problems If you take in more energy than you use you will become overweight or. Being overweight puts a strain on your and can increase your blood pressure. This can lead to heart disease. It also puts strain on your joints and can lead to. You lose weight by ; eating fewer saturated fats and carbohydrates. Eating too little food can lead to you getting tired easily, your muscles wasting and a fall in your rate. It also means you do not get the vitamins and minerals you need for your body to work properly. diabetes dieting heart metabolic obese 11. Microorganisms Semmelweiss discovered that disease was spread by. Lister developed carbolic soap which was an. Pasteur showed that microorganisms came from the. Microorganisms need water, food and a warm temperature to grow. Disease-carrying microorganisms are called. There are four types of pathogen; bacteria, viruses, fungi and parasites. Pathogens can be passed from one person to another by air droplets, touch, faeces, dirty water, bad food and blood. Washing and cleaning help to keep pathogens away. This is called. air antiseptic germs hygiene pathogens

8 12. Protection against disease Your body prevents infection by the skin, hairs in your nose, tears and white blood cells. Some white blood cells engulf, others make that target pathogens. Some bacteria produce toxins. These toxins are destroyed by. Infectious diseases are spread because pathogens are passed from person to person. A disease that spreads over a population is called an. A disease that spreads across the world is called a. antibodies antitoxins epidemic pandemic pathogens 13. The fight against disease Medicines like painkillers help to treat the of disease but they do not kill the pathogens that cause the disease. Some can be used to kill bacteria inside our body. Others can be used to stop bacteria from reproducing. cannot be killed using antibiotics because viruses reproduce inside cells. Using drugs to kill viruses might damage the of our body and make us ill. If we are to a pathogen it cannot harm us. We can be vaccinated to make us immune to some pathogens. A vaccine contains dead pathogens. antibiotics cells immune symptoms viruses

9 14. Drug development Over time many pathogens become to medicines. This happens because some. Some of these mutations survive because of natural selection. New types of the same pathogen are called strains. If we use antibiotics too often it can lead to that are resistant to them. Medicines have to be before they are used by people. These tests are called trials. Thalidomide was a drug that caused babies to be born with physical deformities. It has recently been used to treat leprosy. Many medicines come from plants that indigenous peoples have known about for a long time. clinical mutate resistant superbugs tested

10 B1a Assessment exercises Part A 1 Which of the following diseases is NOT caused by smoking tobacco? a cancer b emphysema c bronchitis d influenza 2 When you get hot during exercise, which of the following does not happen? a vasodilation b vasoconstriction c get hot d sweat 3 Which of these is an example of negative feedback? a control of water through the lungs b hypothermia c heat stroke d diabetes (1 mark) (1 mark) (1 mark) 4 The graph shows how the number of bacteria has changed over a period of time. a Both variables are continuous. b Neither variable is continuous. c Time is the only continuous variable. d The number of bacteria is the only continuous variable. (1 mark) 5 In the graph in question 4, which piece of data is anomalous? a A b B c C d D (1 mark)

11 6 The diagram below shows a neurone. Match the words with their jobs. (4 marks) a b c d i ii iii iv relay neurones motor neurones sensory neurone receptors carry impulses to the spinal cord carry impulses through the spinal cord and up to the brain take the spinal cord to an effector sensor that detecs stimuli 7 Copy and complete the sequence below, showing the route an impulse takes along the nervous system, using the following words: effector sense organ motor neurone sensory neurone (4 marks) 3 In the table below, match the following hormones to the glands that they are secreted from: glucagon thyroxine ADH oestrogen Gland Pituitary Thyroid Pancreas Ovary Hormone (4 marks) 4 The Body Mass Index (BMI) is used to tell us whether we have the correct weight for our height. Match the BMI figures a f, shown below, with the spaces in sentences i iv. You do not have to use all the BMI figures. (4 marks)

12 BMI a Less than 15 b c d e f 35+ i ii iii iv An ideal BMI would be. Somebody who is obese would have a BMI of. Somebody who is suffering from Anorexia Nervosa might have a BMI of. Somebody who is a little overweight would have a BMI of. (4 marks) 5 Look at the data below that shows the caffeine content of some popular drinks. a Type of drink b Average caffeine content (mg) for a typical measure Instant coffee 70 Tea 60 Cola brand 1 64 Cola brand 2 43 Cola brand 3 61 Energy drink 80 Sugar-free cola 46 Coffee (large) 500 Coffee (filter) on average 130 The variables are: a Type of drink b Average caffeine content (mg) for a typical measure i ii iii iv Which variable is categoric? Which variable is continuous? Which variable is discrete? Which variable is dependent? (4 marks) Total (Part A) 25 marks