Biology- Keeping Healthy

Keeping Healthy

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Keeping Healthy

Diet and Excercise

  • A balanced diet includes everything needed to keep the body healthy
  • Different people need different amounts of energy because the metabolic rate varies from person to person
  • If the energy (food) taken in is less than the energy used the person will lose mass. The more exercise you take, the more food you need
  • Mineral ions and vitamins are needed to keep the body healthy. If the diet is unbalanced a person can be malnourished 
  • A healthy diet has the right balance of food types. Carbohydrate, fat and protein are used by the body to release energy and to build cells
  • If you exercise, more energy is used by the body. Exercise increases the metabolic rate, which means that the chemical reactions in cells work faster
  • The proportion of muscle to fat in your body and your inherited factors can also affect your metabolic rate
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Keeping Healthy

Weight Problems

  • If you eat more food (take in more energy) than you need your mass will increase 
  • People who are very fat are said to be "obese"
  • Obesity can lead to health problems such as Type 2 diatbetes (high blood sugar)
  • It is also unhealthy to be seroisly underweight
  • Exercise helps to keep the body healthy
  • It is important for good health to get the energy balance correct
  • Some people are unhealthy because they have too little food (starvation). They find it difficult to walk about and may suffer from deficiency diseases sue to lack of vitimins or minerals
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Keeping Healthy

Inheritance, exercise and health

  • Inherrited factors affect our health. These include metabolic rate and cholesterol levels
  • People who exercise regularly are usually healthier than those who take little exercise
  • Your metabolic rate can be affected by the genes you ingerit from your parents
  • There are two types of cholesterol. You need "good" cholesterol for your cell membranes and to make vital substances
  • Small numbers of the population inherit high levels of "bad" cholesterol, which can lead to heart disease
  • Food rich in saturated fat can also increase blood cholesterol levels
  • By exercising regularly a person can increase their metabolic rate and lower high cholesterol levels
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Keeping Healthy

Pathogens and disease

  • Pathogens are microorganisms that cause infectious diease
  • Most pathogens are either bacteria or viruses
  • Pathogens reprodce rapidly inside the body and may produce toxins
  • Viruses reproduce inside cells and damage them
  • Washing hands removes pathogens from them. Semmelweiss was the first doctor to realise this
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Keeping Healthy

Defence Mechanisms

  • The body prevents most pathogens getting in
  • Pathogens which enter the body can be destroyed by white blood cells
  • The skin prevents pathogens getting into the body
  • Pathogens are also trapped by mucusand killed by stomach acid
  • White blood cells are part of the immune system. They do three things to defend the body:
  • They can ingest pathogens. This means they digest and destory them
  • They produce antibodies to help destroy particualr pathogens
  • They produce antitoxins to counteract the toxins (poisons) that pathogens priduce
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Keeping Healthy

Using drugs to treat disease

  • Some meficines may relieve the symptoms of disease but not kill the pathogens that cause it
  • Antibiotics cure bacterial diseases by killing the bacteria inside the body
  • Antibiotics cannot destroy viruses
  • Viruses are difficult to destroy because they reproduce inside body cells
  • Penicillin is an antibiotic, but there are many others. It was first discovered by Alexander Fleming in 1928
  • Painkillers and other drugs relieve the symptoms of a disease but do not kill the pathogen
  • Your immune system will usually overcome the viral pathogens
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Keeping Healthy

Growing and investigating bacteria

  • Bacteria can be grown on agar jelly
  • All the materials and equipment must be sterilised. This ensures that unwanted microoganisms do not infect the culture 
  • Uncontaminated cultures can be used to investigate the effect of anitbiotics and disinfectants on the bacteria
  • Pure cultures of non-pathogens (safe) bacteria can be used for laboratory investigations
  • Contamination might come from your skin, the air, the soil or the water around you
  • To culture (grow) microorganisms in a laboratory you must:
  • Give them a liquid or gel containing nutrients- a culture medium. It contains carbohydrate as an energy source, various minerals and sometimes other chemicals
  • Privide warmth and oxygen
  • Keep them incubated at 25 degrees in school laboratories and at 35 degrees in idustry
  • To keep the culture pure you must:
  • Kill all the bacteria on the equipment
  • Prevent microorganisms from the air getting into th eequipment
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Keeping Healthy

Changing Pathogens

  • If a pathogen changes by mutation the new strain may spread rapidly
  • Some new strains can cause epidemics and pandemics
  • Some bacteria have developed resistance to antibiotics by natural selection
  • Very few people are immune to these changed pathogens so diease can spread quickly
  • The MRSA "super bug" is a bacterium that has evolved through natural selection. MRSA and other bacteria have become resistant to the common antibiotics
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Keeping Healthy


  • A wide range of vaccines are given to immunise people against disease
  • Vaccines contain dead or inactive pathogens
  • Vaccines can protect against both bacterial and viral pathogens
  • Vaccines encourage your white blood cells to produce antibodies that destroy the pathogens 
  • The antibodies recognise the antigen (the protein shape) on the pathogen
  • The MMR vaccination (immunisation) is one of several vaccines. MMR is given to prevent measles, mumps and rubella
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How do we deal with desease?

  • Vaccination protects individuals and society from the effects of diease
  • The treatment of disease has changes as our understanding of antibiotics and imminity has increased
  • Most people in a population need to be vaccinated to protect society from vey serious diseases
  • Diseases such as measles can lead to long term damage to the body, such as deafness and occasionally death
  • Some vaccines cause side effects which may be mild or serious
  • Overuse of antibiotics can lead to the development of new strains of bacteria
  • Doctors do not prescribe antibiotics for mild infections such as minor sore throats
  • Scintists are always trying to find new ways of treating disease
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