B1 Keeping Healthy

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  • Keeping Healthy
    • Diet and Metabolic Rate
      • For good health, your diet must provide the energy you need
        • Because the different food groups have different uses in the body, you need to have the right balance of foods as well
          • You need enough carbohydrates to release energy
          • You need enough fats to keep warm and release energy
            • Too much of saturated fats can raise your cholesterol level
          • You need enough protein for growth, cell repair and cell replacement
          • You need enough fibre to keep everything moving smoothly through your digestive system
          • You need tiny amounts of various vitamins and mineral ions to keep your skin, bones, blood and everything else generally healthy
            • Sodium (salt) is one of said mineral ions, and it can lead to health problems, including high blood pressure
      • You need energy to fuel the chemical reactions in the body that keep you alive
        • These reactions are called your metabolism, and the speed at which they occur is your metabolic rate
          • There are slight variations in the resting metabolic rate of different people
            • For example, muscle needs more energy than fatty tissue which means (all other things being equal) people with a higher proportion  of muscle to fat in their bodies will have a higher metabolic rate
              • Regular exercise can boost your resting metabolic rate because it builds muscle
            • However, physically bigger people are likely to have a higher metabolic rate than smaller people - the bigger you are, the more energy your body needs to be supplied with (because you have more cells)
            • Men tend to have a slightly higher rate than women - they're slightly bigger and have a larger proportion of muscle
            • Other genetic factors may also have some effect
          • When you exercise, you obviously need more energy - so your metabolic rate goes up during exercise and stays high for some time after you finish (particularly if the exercise is strenuous)
            • So people who have more active jobs need more energy on a regular basis - builders require more energy per day than office workers, for instance
            • This means your activity level affects the amount of energy your diet should contain
              • If you do little exercise, you're going to need less energy, so less fat and carbohydrate in your diet, than if you're constantly on the go
    • Factors Affecting Health
      • People whose diet is badly out of balance are said to be malnourished
        • Malnourished people can be fat or thin, or unhealthy in other ways
          • Malnourishment is different from starvation, which is not getting enough food of any sort
            • People whose diet is badly out of balance are said to be malnourished
              • Malnourished people can be fat or thin, or unhealthy in other ways
                • Malnourishment is different from starvation, which is not getting enough food of any sort
                  • The effects of malnutrition vary depending on what foods are missing from the diet
                    • Problems commonly include:
                      • Slow growth in children
                      • Fatigue
                      • Poor resistance to infection
                      • Irregular periods in women
                    • Deficiency diseases are caused by a lack of vitamins or minerals
                      • For example, a lack of vitamin C can cause scurvy, a deficiency disease that causes problems with the skin, joints and gums
            • The effects of malnutrition vary depending on what foods are missing from the diet
              • Problems commonly include:
                • Slow growth in children
                • Fatigue
                • Poor resistance to infection
                • Irregular periods in women
              • Deficiency diseases are caused by a lack of vitamins or minerals
                • For example, a lack of vitamin C can cause scurvy, a deficiency disease that causes problems with the skin, joints and gums
        • Excess carbohydrate or fat in the diet can lead to obesity
          • Obesity is a common disorder in developed countries - it's defined as being 20% over maximum recommended body mass
          • Hormonal problems can lead to obesity, though the usual cause is a bad diet, overeating and a lack of exercise
          • Health problems that can arise as a result of obesity include:
            • Arthritis (inflammation of the joints)
            • Type 2 diabetes (inability to control blood sugar level)
            • High blood pressure
            • Heart disease
        • Too much saturated fat in your diet can increase your blood cholesterol level
        • Eating too much salt can cause high blood pressure and heart problems
        • Some people suffer from lack of food, particularly in developing countries
        • Exercise is important as well as diet - people who exercise regularly are usually healthier than those who don't
          • Exercise increases the amount of energy used by the body and decreases the amount stored as fat
            • It also builds muscle so it helps to boost your metabolic rate
              • That means people who exercise are less likely to suffer from health problems such as obesity
                • However, sometimes people can be fit but not healthy - e.g. you can be physically fit and slim, but malnourished at the same time because your diet isn't balanced
        • Your health can depend on inherited factors too
          • Some people may inherit factors that affect their metabolic rate
            • For example, some inherited factors cause an underactive thyroid gland, which can lower the metabolic rate and cause obesity
          • Other people may inherit factors that affect their blood cholesterol level
            • Cholesterol is a fatty substance that's essential for good health - it's found in every cell in the body
              • Some inherited factors increase blood cholesterol level, which increases the risk of heart disease
      • Pathogens
        • Pathogens are microorganisms that enter the body and cause disease
        • There are two main types of pathogen: bacteria and viruses
          • Bacteria
            • Bacteria are very small cells (about 1/100th the size of human body cells), which can reproduce rapidly inside the body
            • They make you feel ill by damaging your cells and producing toxins
          • Viruses
            • Viruses are not cells
              • They're tiny, about 1/100th the size of a bacterium
            • They replicate themselves by invading your cells and using the cells' machinery to produce many copies of themselves
              • The cell will usually then burst, releasing all the new viruses, and this cell damage is what makes you feel ill
      • Fighting Disease
        • Your skin, plus hairs and mucus in your respiratory tract, stop a lot of microorganisms getting inside your body
        • To try and prevent microorganisms getting into the body through cuts, small fragments of cells called platelets help blood clot quickly to seal wounds
        • White blood cells travel around in the blood, constantly patrolling for microbes
          • When they come across an invading microbes they have three lines of attack:
            • White blood cells can engulf foreign cells and digest them
            • Antibodies
              • Every invading cell has unique molecules called antigens on its surface
                • When white blood cells come across a foreign antigen, they will start to produce proteins called antibodies to lock onto and kill the invading cells
                  • The antibodies produced are specific to that type of antigen - they won't lock onto any others
                    • If the person is infected with the same pathogen again the white blood cells will rapidly produce the antibodies to kill it - the person is naturally immune to that pathogen and won't get ill
                  • Antibodies are then produced rapidly and carried around the body to kill all similar bacteria or viruses
            • Antitoxins - these counter toxins produced by the invading bacteria
        • Vaccination
          • Vaccinations protect from future infection
          • When you're infected with a new microorganism, it takes your white blood cells a few days to learn how to deal with it
            • Vaccinations involve injecting small amounts of dead or inactive microorganisms
              • These carry antigens, which cause your body to produce antibodies to attack them
                • This means that if live microorganisms of the same type appear after that, the white blood cells can rapidly mass-produce antibodies to kill off the pathogen
                  • This is because the white blood cells have remembered the antibodies required for that antigen
          • Advantages
            • Vaccines have helped control lots of infectious diseases that were once common in the UK
            • Disease epidemics can be prevented if a large percentage of the population is vaccinated
              • Even the people who aren't vaccinated are unlikely to catch the disease because there are fewer people able to pass it on
          • Disadvantages
            • Sometimes they don't give you immunity
            • Although they are very rare, you can sometimes have a bad reaction to a vaccine
        • Some medicines, including painkillers, help to relieve the symptoms of infectious disease, but do not kill the pathogens.
        • Antibiotics, including penicillin, are medicines that help to cure bacterial disease by killing infectious bacteria inside the body
          • Antibiotics cannot be used to kill viral pathogens, which live and reproduce inside cells
            • It is important that specific bacteria should be treated by specific antibiotics
              • The use of antibiotics has greatly reduced deaths from infectious bacterial diseases
                • Many strains of bacteria, including MRSA, have developed resistance to antibiotics as a result of natural selection
                  • Overuse and inappropriate use of antibiotics has increased the rate of development of antibiotic resistant strains of bacteria
                    • To prevent further resistance arising it is important to avoid over-use of antibiotics
                      • Now, antibiotics are not used to treat non-serious infections, such as mild throat infections, so that the rate of development of resistant strains is slowed down
                    • Antibiotics kill individual pathogens of the non-resistant strain
                      • Individual resistant pathogens survive and reproduce, so the population of the resistant strain increases
                        • The development of antibiotic-resistant strains of bacteria necessitates the development of new antibiotics
                          • The new strain will then spread rapidly because people are not immune to it and there is no effective treatment
                  • To prevent further resistance arising it is important to avoid over-use of antibiotics
                    • Now, antibiotics are not used to treat non-serious infections, such as mild throat infections, so that the rate of development of resistant strains is slowed down
                  • Mutations of pathogens produce new strains
                    • Antibiotics and vaccinations may no longer be effective against a new resistant strain of the pathogen
                      • The new strain will then spread rapidly because people are not immune to it and there is no effective treatment
            • It is difficult to develop drugs that kill viruses without also damaging the body’s tissues
        • Semmelweis recognised the importance of hand-washing in the prevention of spreading some infectious diseases
          • By insisting that doctors washed their hands before examining patients, he greatly reduced the number of deaths from infectious diseases in his hospital
        • Uncontaminated cultures of microorganisms are required for investigating the action of disinfectants and antibiotics
          • For this
            • Petri dishes and culture media must be sterilised before use to kill unwanted microorganisms
            • inoculating loops used to transfer microorganisms to the media must be sterilised by passing them through a flame
            • the lid of the Petri dish should be secured with adhesive tape to prevent microorganisms from the air contaminating the culture
          • In school and college laboratories, cultures should be incubated at a maximum temperature of 25°C, which greatly reduces the likelihood of growth of pathogens that might be harmful to humans.
            • In industrial conditions higher temperatures can produce more rapid growth

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