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Food and Digestion End of topic project James Persico


Food and Digestion

The balance of nutrients in your body is essential to maintain a healthy lifestyle, and reduce the risk of deficiencies and diseases later in life. This can be achieved by eating enough of each main type of nutrient. Outlined below are the most important components of what you eat: Carbohydrates Packed with energy, these complex sugars are used by athletes and sportsmen to maintain stamina during long periods of exercise. They are most commonly found in bread, pasta, potatoes and rice. We did experiments on certain foods in Science lessons, using iodine, to determine whether they had carbohydrates in them. If the iodine came into contact with a complex sugar, it turned the food black. Otherwise, it remained crimson. Carbohydrates are made up of complex sugars. These are harder to break down than simple sugars, so take longer. Pasta and bread are described as ‘slow release’ as they release energy slower than foods with simple sugars. One complex sugar is starch, it is broken down into the simple sugar of glucose, which tastes very sugary on the tongue. Sugar This provide fast release energy, as it gives an energy boost almost immediately (sugar rush), but runs down very quickly (sugar crash). This can lead to a depressed feeling after half an hour, and cravings for the sugar 'high'. Too much sugar, as we will find out later, can be bad for the body right from the start. Protein Proteins help build the body’s parts during the infant years, and help maintain the brain, blood, body and skin throughout your life. Infants need more of these to help their bodies grow well during early years. Minerals Used to maintain the bones and teeth, minerals are found in liver, eggs and cheese. Water Water is essential for every living creature on earth. It is made up of 2 hydrogen atoms and one oxygen atom, bonded together. Over 60% of the earth's surface is covered in water, but only 1-2% of it is fit for drinking, as the rest is salt water, which can be poisonous in large quantities. Roughage Roughage smooths the passing of food down the large intestine. Lack of it can cause constipation, while too much can cause diarrhoea. Roughage itself is not digested by the body, but lubricates the insides.

Vitamins Vitamins are chemicals which help different parts of your body in a variety of different ways, listed below

Vitamin Name

Found in


A deficiency of this causes


Liver, milk, butter and eggs

Helps eyesight



Fresh vegetables, nuts and wholemeal bread

Helps the body get energy out of food



Lemons, oranges,

Makes dopamine



Cod liver, the sun and dairy products

Strengthens bones and fingernails

Weak bones


Asparagus, spinach and milk

Helps heal cuts and bruises

‘Liver spots’ and sagging skin


Green vegetables, liver

Helps the blood clot

Excessive bleeding from cuts

Why have a balanced diet? Lack of a sensible and well balanced diet can have very serious implications for your general health. Scurvy is a painful disease that causes bleeding gums and skin irritation and affects people with a lack of Vitamin C. It was rife among sailors in the 18th century, when long voyages were made, with virtually no fruit on board. Various remedies were tried with unsuccessful results. In James Lind’s tests, vinegar and garlic were of no help, and neither was cider (to the disappointment of the sailors), but Scurvy oranges and limes seemed to stave off scurvy. However, while Lind knew that Vitamin C rich foods prevented scurvy, the Navy used them only as a remedy until the 19th century. The disease Rickets, where bones become soft or fracture easily, is caused by insufficientf calcium and Vitamin D, so during the period of rationing in WWII, lack of certain foods such as eggs meant that many children suffered from bent bones.

The guideline daily amounts for men, women and children

Obesity and Malnutrition People with excessive quantities of fat in their bodies are said to be obese. Obesity can cause lifethreatening illnesses such as heart disease, cancer, diabetes, liver disease, high blood pressure and mental health problems. The World Health Organisation (WHO) has classified obesity as a global epidemic, with over 1 in 5 adults affected by it in England. America is also facing problems with obesity, rates of which have increased sharply since the advent of supermarkets, fast food restaurants and the car. Obesity can be prevented by eating fat and sugar only in moderation, and consuming plenty of roughage, protein and water.

Male Obesity

no data <5% 5-10% 10-15% 15-20% 20-25% 25-30% 30-35% 35-40% 40-45% 45-50% 50-55% >55%

Malnutrition is at the other end of the scale. It is a lack of nutrients, especially fat, which can lead to a gaunt and ill looking face. Malnutrition far outweighs obesity as a global problem; while many people in developed countries are looking to slim down, over 1/6 of the worldâ&#x20AC;&#x2122;s population does not have enough food. This means they cannot get enough nutrients in their diet. Although malnourishment mainly affects underweight people, obese people may also be affected. Malnutrition usually occurs in developing countries, but also affects individuals with anorexia in developed countries. Anorexia is sometimes coupled with bulimia, which is when a person eats too much, then tries to vomit the food up before it reaches the intestines. This damages the enamel on the teeth very badly. Teeth An adult should have 32 teeth, all of them permanent. In early years, an infant will grow 28 'milk teeth', smaller versions of the permanent teeth which are to follow. The milk teeth usually fall out when the child is 8-12 years old, and are replaced by stronger, larger permanent teeth. If the permanent teeth are damaged or knocked out, there is no natural way to replace them, but a false tooth can be inserted

through surgery.

Dental Hygiene Bacteria living in the mouth excrete acids, which damage the teeth. When sugar meets the bacteria, the bacteria begin to eat it and excrete more acids, damaging the teeth. It is recommended that the teeth are brushed twice a day, once in the morning and once at night, although brushing after lunch is not harmful. Toothpaste often contains fluoride, which can mimic the effects of enamel. Brushing too vigorously can damage the enamel coating of the teeth, which can let bacteria into the dentine, and eventually into the nerves, after which extreme toothache can follow. The enamel is a dead layer, and, Incisors – pull food into the mouth Canines – Tear food apart Premolars – begin to grind food Molars – Grind food to a pulp Wisdom teeth – emerge when adult, act as molars.

once formed, cannot grow when damaged. The teeth are arranged as shown above. Digestion The first stage of digesiton takes place in the mouth, when the teeth start to physically tear and then crush the food. Saliva’s enzymes then begin to affect the food, dissolving certain elements of it with enzymes. The food then goes down the throat and past certain glands, such as the the thyroid gland. This absorbs thyroxine, which helps the body grow during the age of puberty. After the glands, food is forced through the oesophagus, a tight, muscle filled tube which pushes food down into the stomach, where chemical digestion begins. Chemical digestion in the stomach is largely achieved by using very strong acids such as hydrochloric acid, which dissolve food into what resembles a lumpy soup. When a human vomits, the stomach contracts, and food is forced up the oesophagus, through the mouth, and hopefully outside the body. Vomit still contains powerful acids, so it is best for sick people to brush their teeth regularly, to neutralise the effects of the enamel stripping chemicals. After food passes through the stomach, the pancreas produces enzymes and acids that can further dissolve the food into simpler blocks of chemicals. The food is then pushed into the small intestine, which is lined with villi. Villi have the appearance of tiny hairs, and absorb nutrients into the bloodstream before

carrying them to where they are needed. The villi are so small, and cover such an enormous area in total, that they can absorb virtually all of the nutrients in food. The remaining sludge passes out of the small intestine into the large instestine, which, ironically, is smaller than the small intenstine! The large intestine squeezes the sludge, extracting water which it then sends throughout the body, as the body needs water for life. The remaining sludge passes to the colon, where it is stored until it is expelled through the rectum and anus. Role of acids and enzymes Acids play the role of dissolving foods in the stomach and small intestine. The acid found in the stomach is called hydrochloric acid. Enzymes split up chemicals, letting the nutrients in food get small enough to be absorbed into the villi located in the small intestine.

Breaks down: Into: Found in:

Carbohydrase Carbohydrates Starch + Glucose Small intestine + pancreas

Tests positive with:


Protease Protein Amino Acids Stomach, small intestine and pancreas Anti-protease

Lipase Fat Gliserol + fatty acids Small intestine, mouth and cpancreas Anti-lipase

Which Meal Would You Choose? Lunch: Fish (protein) Boiled potates (carbohydrates) Broccoli (vitamins C, K and A)


Mixed salad (folic acid)

Tomato ketchup (Vitamin C and salt)

Bread (carbohydrates and fat) Orange juice (Vitamin C)

Chips (fat and salt)

Bacon sandwich (Protein, salt and fat) Biscuits (Fat, salt and roughage) Lemonade (sugar and Vitamin C)

Food and Digestion  

Project I did in Year 8.

Food and Digestion  

Project I did in Year 8.