Unit 2 - food and health

These cards cover every learning objective of the second module on the biology AS specification. They were made to help me revise so they are in a format which makes sense to me, but I hope they can help other people too!

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Define balanced diet?
One that contains all the nutrients required for health in the appropriate proportions.
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Why do we eat?
To provide better health, to ensure a strong immune system and to avoid illness.
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What is in a balanced diet?
Carbohydrates, proteins, fats, vitamins, minearls, water and fibre/roughage.
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What percentage of carbohydrates, proteins and lipids do you need?
57% carbohydrates, 30% fats and 13% proteins.
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Name sources of carbohydrates?
Pasta, bread, rice and sugar.
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Name sources of fats?
Dairy products and oil.
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Name sources of proteins?
Eggs, meat and fish.
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What is malnutrition?
Is caused by an unbalanced diet. It can be a deficiency (loss of weight) or obesity (gain of weight).
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How is obesity caused?
By consuming too much energy.
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How is Body Mass Index measured?
BMI= mass in kg/hight in m2
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What BMI value is considered underweight?
Less than 18.5.
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What BMI value range is considered healthy?
18.5 - 25
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What BMI value is considered obese?
over 30
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Which health risks are caused by obesity?
Cancer, cardiovascular disease, type 2 diabetes, gallstones, osteoarthritis and high blood pressure.
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What effect does excess salt have in your diet?
Decreases the water potential of your blood, causing more water to move into the blood and causing hypertension.
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What effects does excess cholesterol have on the diet?
High blood cholesterol levels have been linked to 45-47% of deaths from CHD.
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What components of the diet can the risks of CHD be reduced?
Dietary fibre, moderate alcohol consumption and eating oily fish.
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In what form is cholesterol transported in the blood?
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Define lipoprotein?
A combination of lipid, cholesterol and protein, used to transport fats and cholesterol around the body.
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Me the two types of lipoproteins?
High-density lipoprotein and low-density lipoprotein.
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Explain the role of high-density lipoproteins on blood cholesterol levels?
They carry cholesterol from the body tissues to the liver. Liver cells have receptor sites and the cholesterol is broken down in cell metabolism. It reduces blood cholesterol levels.
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Explain the role of low-density lipoproteins on blood cholesterol levels?
They carry cholesterol from the liver to the tissues. Tissue cells have receptor sites that allow LDLs to bind, but if there are high levels of LDLs in the blood, the activity of the receptors decrease. Levels of cholesterol in the blood increase.
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Sources of LDLs?
Animal fats.
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How to lower the concentration of LDLs?
Eat a high proportion of unsaturated fats to increase HDLs, east polyunsaturated fats and monounsaturated fats.
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What is the basis of all food chains?
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How can we make food production more efficient concerning plants?
Improve growth rates of crops, increase the size of the yield from each plant, reduce losses of crops due to disease and pests, make harvesting easier by standardising plant size and improve plant responses to fertilisers.
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How can we make food production more efficient concerning animals?
Improve the rate of growth, increase productivity and increase resistance to disease.
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How can we produce plants and animals that fit these criteria?
Selective breeding and marker assisted selection.
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Define selective breeding?
Is where humans select the individual organisms that are allowed to breed according to chosen characteristics.
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Name the three stages of selective breeding?
Isolation, artificial selection and inbreeding or line breeding.
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Examples of selective breeding?
Farmers breed cattle for high milk production, chickens are breed for egg and meat production and salmon have been bred for faster growth and meat with lower fat content.
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What is marker assisted selection?
A section of DNA is used as a marker to recognise the desired characteristic.
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Examples of marker assisted selection?
Tomatoes an apples have been bred with improved resistance to disease.
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Define pesticide?
A chemical that kills pests.
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Define fungicide?
A chemical that kills fungi.
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Define herbicide?
A chemical that kills plants.
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Define insecticide?
A chemical that kills insects.
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Define antibiotic?
A chemical that kills or prevents reproduction of bacteria.
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List the methods used to prevent food spoilage by microorganisms?
Cooking, pasteurising, drying/salting, smoking, pickling, irradiation, curling, freezing, canning, vacuum wrapping and plastic and paper packaging.
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How does cooking prevent food spoilage?
Denatures enzymes and proteins of microorganism, killing it.
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How does pasteurising prevent food spoilage?
Heating to 72 decrees for short time then cooling to 4 degrees. Kills microorganisms.
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How does drying/salting prevent food spoilage?
Dehydrates microorganism as water leaves cell by osmosis.
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How does smoking prevent food spoilage?
Food develops a hard, dry outer surface and smoke contains antibacterial chemicals.
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How does pickling prevent food spoilage?
pH denatures enzymes and proteins of microorganism, killing it.
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How does irradiation prevent food spoilage?
Ionising radiation disrupts DNA of microorganisms, killing them.
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How does cooling and freezing prevent food spoilage?
Retards enzyme activity so their metabolism, growth and reproduction is very slow.
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How does canning prevent food spoilage?
Food heated and sealed in airtight cans, denaturing enzymes, killing microorganisms and prevent aerobic respiration.
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How does vacuum wrapping prevent food spoilage?
Air is excluded so microbes cannot respire aerobically.
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Advantages of using microorganisms to make food?
Production of protein can be faster than an animal, production can be increased and decreased to demand, there are no animal welfare issues, good source of proteins for vegetarians and they contain no animal fat or cholesterol.
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Disadvantages of using microorganisms to make food?
Many people do not want to eat fungi or food grown on waste, proteins need to be isolated, protein has to be purified, conditions of production are ideal for infection so precautions must be taken and protein does not have same taste as meat.
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Examples of use of microorganisms to make food?
Yogurt is made using Lactobacillus, bread is risen using yeast and alcohol is made using yeast. More recently Quorn has been made using Fusarium venenatum.
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Define health?
A state of metal, physical and social wellbeing, not just the absence of disease.
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Define disease?
A departure from good health caused by a malfunction of the mind or body.
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Define parasite?
An organism that lives in or on another living thing, causing harm to its host.
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Define pathogen?
An organism that causes disease.
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Examples of parasites?
Tapeworms and head louse.
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List the organisms that cause infectious disease?
Bacteria, fungi, viruses and protoctista.
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Examples of bacteria?
Cholera is caused by Vibrio cholerae and TB is caused by Mycobacterium tuberculosis.
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Examples of fungi?
Athlete's foot and ringworm are caused by Tinea.
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Examples of viruses?
Influenza, Human Immunodeficiency Virus and Tobacco Mosaic Virus.
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Examples of protoctista?
Malaria is caused by Plasmodium.
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Define transmission?
Is the way in which a parasitic microorganism travels from one host to another.
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Name the three most common forms of transmission?
By means of a vector, physical contact or droplet infection.
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Explain the means of transmission of malaria?
Bitten by a female Anopheles mosquito which carries malaria, careless and unhygienic medical practices, unscreened blood transfusion, use of unsterilised needles and across the placenta to an unborn child.
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Explain the transmission and life cycle of malaria via mosquito?
Person malaria, have plasmodium gametes in blood, female Anopheles mosquito bites, zygote forms in mosquitos stomach, migrates to mosquitos silvery gland, bites other person, plasmodium injected to persons blood, migrates to liver, blood.
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Explain the causes of HIV/AIDS?
Virus enters body and remains inactive, one active it destroys T-helper cells in immune system, unable to defend against infection and the effects of the diseases kills a person.
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Explain the transmission of HIV/AIDS?
Exchange of bodily fluids such as blood to blood contact, unprotected sex, unscreened blood transfusions, use of unsterile surgical equipment, sharing hypodermic needles, 'needle-stick', across placenta during childbirth and during breastfeeding.
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Explain the cause of tuberculosis (TB)?
It is caused by the bacteria Mycobacterium tuberculosis and Mycobacterium bovis. It affects the lungs.
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Explain the transmission of TB?
The bacteria are contained in tiny droplets of liquid released when an infected person sneezes, coughs or talks. Another person inhales the droplets and this can cause TB.
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The factors that make the contraction of TB more likely?
Overcrowding, poor ventilation, poor health, poor diet, homelessness and living or working with people who have migrated form areas where TB is more common.
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Which factors may contribute to the poor health of people?
Poverty, lack of proper shelter, poor nutrition, poor hygiene, lack of investment by government, poor or inadequate health services, poor education about diseases o cicil unrest or warfare.
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How many people does malaria kill a year?
3 million.
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How many people are affected by malaria worldwide?
300 million.
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Where is malaria most common?
90% of people with malaria live in sub-Saharan Africa.
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How many people are living with HIV/AIDS?
45 million.
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How many people are newly infected with HIV/AIDS each year?
5 million.
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How many people have died from HIV/AIDS related diseases?
30 million.
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Where is HIV/AIDS most common?
Over half the cases are in sub-Saharan Africa.
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What percentage of the worlds population become infected with TB a year?
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What percentage of the population are infected with TB?
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How many people contracted TB in 2005?
8.8 million.
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How many people died from TB in 2005?
1.6 million.
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Where is TB most common?
South-east Asia and sub-Saharan Africa.
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What is it possible to do through epidemiology?
Identify the cause of a disease and the risk factors, determine the incidence, prevalence, mortality and morbidity, study how fast a disease is spreading, identify countries and people at risk and check how well control programs are working.
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What can governments do to control diseases spreading?
Introduce education programs, advertisement to raise awareness, screening programs, specialised healthcare, vaccination programs and target research.
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Define immune response?
The specific response to a pathogen, which involves the action of lymphocytes and the production of antibodies.
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What are the primary defences?
The skin, mucous membranes, antibodies in tear fluid and wax in the ear canal.
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Outline how the skin forms a defence to pathogens?
The outer layer (epidermis) consists of layers of cells called keratinocytes. They're produced at the base of the epidermis and migrate to the surface. As they migrate the cytoplasm is replaced by keratin.
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Outline how the mucous membranes form a defence against pathogens?
The epithelial layer contains mucus-secreting goblet cells. Mucous lines the passages and traps any pathogens. The epithelium also has ciliated cells which waft the layer of mucous along.
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What is the secondary defence?
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What are the two types of phagocytes?
Neutrophils and macrophages.
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Where are phagocytes manufactured?
Bone marrow.
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How do phagocytes remove a pathogen?
Phagocytes engulf and destroy pathogens. Pathogens have antigens on their membrane, these are recognised as foreign. Antibodies in the blood attach to the antigens. Phagocytes have receptors in membranes that bind to the antibodies, phagocytosis.
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Outline phagocytosis?
Pathogen attached to phagocyte by antibody and surface receptors, pathogen engulfed by infolding of phagocyte membrane, lysosome releases lysins into phagosome, pathogens digested, harmless products of digestion are absorbed.
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Define antigen?
Molecules that stimulate an immune response.
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Define antibody?
Protein molecules that can identify and neutralise antigens.
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What is the structure of an antibody?
Y shaped, made up of two regions, a constant region and variable region. Four polypeptide chains held together by disulphide bridges. The constant region allows attachment to phagocyte and variable region ensure attachment to correct antigen.
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Antibodies work in two ways, name them?
Neutralisation and agglutination.
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Explain neutralisation?
Antibodies cover the pathogen binding sites, preventing the pathogen from banging to a host cell and entering the cell.
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Explain agglutination?
A large antibody that can bind many pathogens together. The group of pathogens is too large to enter a host cell.
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What are the two phases of immune response?
Primary response and secondary response.
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How are the primary and secondary immune response different?
The primary response takes around 5 days to respond, and can take a further 10 days for the antibodies i the blood to rise to a level it can combat the pathogen. Secondary response starts sooner, is more rapid and reaches a higher concentration.
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Define cell signalling?
The communication between cells that allows effective coordination of a response.
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*gap left for immune response which i don't get and need to ask my teacher*
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Define vaccination?
Is the deliberate exposure to antigenic material, which activates the immune system to make an immune response and provide immunity.
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Which two methods of vaccination can control disease?
Herd vaccination (provide vaccination to all at risk, almost all population) or ring vaccination (used when new case reported, vaccinate those in immediate vicinity)
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What is active immunity?
Immunity achieved by the activation of the immune system. Lymphocytes produce antibodies and release them into the blood, immunity lasts for a log time.
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What is passive immunity?
Immunity achieved by antibodies not made by stimulating the patients immune system. Antibodies may be passed by breastfeeding, the placenta or intravenous injection. Short lasting immunity.
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What is natural immunity?
Gained in the normal course of living processes, as a result of an infection that stimulates the immune response.
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What is artificial immunity?
Immunity that is gained by deliberate expose to antibodies or antigens.
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Why do we need to look for new drugs?
New diseases are emerging, there are still diseases that have no treatment and some antibiotics are becoming less efficient.
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Where could we look for new drugs?
By accident, looking at traditional medicine, the observation of wildlife and modern research.
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What harmful substances are contained in cigarette smoke?
Tar, carbon monoxide and nicotine.
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What short term harm does the tar cause?
Settles in the airways and alveoli, creating a greater diffusion distance. It may cause an allergic reaction, causing the walls of the airways to contract. Destroys the cilia so they are unable to move the mucous and stimulates goblet cells.
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What long term harm does the tar cause?
Smoker's cough is an attempt to remove the bacteria laden mucous collected in the lungs. The coughing damages the lining of the airways, which is replaced by scar tissue which is tough and inflexible and thicken the airways.
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Why do the alveoli burst as a result of smoking?
Constant presence of bacteria causes airways to become inflames, attracting white blood cells. White blood cells release enzyme elastase. Damages elastic tissue, bronchioles collapse and air is trapped in alveoli.
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How does smoking cause cancer?
Cigarette smoke contains carcinogenic compounds. Benzopyrene is most harmful, enters nucleus of cells in lungs and has effect on genetic material. Causes mutation, uncontrolled cell division takes place.
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What diseases are associated with smoking?
Lung cancer, chronic bronchitis, emphysema, chronic obstructive pulmonary disease.
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What diseases do carmon monoxide and nicotine cause?
Atherosclerosis, coronary heart disease and a stroke.
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What does nicotine do in the body?
Mimics the action of the transmitter substances at synapses between nerves, making the body feel more alert. Causes the release of adrenaline. Constricts the arteries leading to the extremities. Makes platelets sticky, increasing risk of blood clots.
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What does carbon monoxide do in the body?
Enters red blood cells and combine with haemoglobin, forming carbooxyhaemoglobin. Damages the lining of the arteries.
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Problems caused by the changes to the blood system?
Atherosclerosis, thrombosis, coronary heart disease and strokes.
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Outline atherosclerosis?
CO/high blood pressure damages endothelium of arteries, damage repaired by action of phagocytes, which encourage growth of smooth muscle and deposition of fatty substances, cholesterol. Deposits also contain fibres, dead blood cells and platelets.
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Outline thrombosis?
Atheroma's form a plaque which sticks out into lumen of artery. Blood cannot flow smoothly past plaque, increasing chance it will clot.Sticky platelets also increase risk. Clots stop flow of blood, and can travel in blood, blocking other arteries.
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Outline coronary heart disease?
Arteries that carry blood to heart muscle called coronary arteries. Blood at high pressure and prone to atherosclerosis. Reduces blood flow to heart muscle. Can result in angina, heart attack or heart failure.
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Outline stroke?
Death of a part of the brain tissue. Caused by loss of blood flow to that part of brain. Can result form a blood clot blocks small artery in brain or an artery leading to brain bursting.
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Define coronary heart disease?
Is a disease of the heart caused by malfunction of the coronary arteries.
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Define stroke?
Is the death of part of the brain due to a lack of blood to that part of the brain.
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List cardiovascular diseases?
Atherosclerosis, coronary heart disease, stroke and arteriosclerosis.
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Symptoms of CHD?
Person out of breath and angina.
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Symptoms of a stroke?
Sudden numbness, confusion, difficulty seeing, difficulty walking and severe headache.
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Factors increasing risk of CHD?
Age, sex, hypertension, high blood cholesterol, physical inactivity, high animal fat diet, high salt intake, absence of healthy fats, genetic factors, diabetes and stress.
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Define epidemiology?
The study of the distribution of a disease in populations and the factors that influence its spread.
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Which three links have epidemiologists discovered between disease and smoking?
A regular smoker is 3 times more likely to di prematurely compared to a non smoker, 50% of smokers will die from smoking related diseases and the more cigarettes a person smokes a day the more likely they are to die prematurely.
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Evidence linking smoking and lung cancer?
A smoker is 18 times morvlikey to develop lung cancer, 25% of smoker die of lung cancer, chance of developing lung cancer decreases when stop smoking.
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Evidence linking smoking and cardiovascular disease?
Substances release in cigarettes influence the circulatory system in a way to enhance atherosclerosis and other circulatory diseases.
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Other cards in this set

Card 2


Why do we eat?


To provide better health, to ensure a strong immune system and to avoid illness.

Card 3


What is in a balanced diet?


Preview of the front of card 3

Card 4


What percentage of carbohydrates, proteins and lipids do you need?


Preview of the front of card 4

Card 5


Name sources of carbohydrates?


Preview of the front of card 5
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