topic 1: nutrition and digestion
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Eating good food, especially with family and friends, is one of the pleasures of life.We all know that people who eat healthy, balanced diets are likely to have:
In this unit you will learn about how and why we need nutrients and how our bodies are supplied with energy.
- plenty of energy to work and enjoy themselves;
- fewer infections and other illnesses.
In this unit you will learn about how and why we need nutrients and how our bodies are supplied with energy.
Explain why we need food
Just as a power station requires gas or coal to power its turbines and generate energy, so we need fuel – in the form of food – to power our continued existence.
The foods we eat provide us with a range of nutrients: vitamins, minerals, water, fat, carbohydrates, fibre, and protein. These nutrients are put to different uses — as building materials to construct the tissues and organs from which our bodies are made; as the components of the molecular machinery that keeps our cells running as they should. All of these uses are unified by a common theme: a requirement for energy to make them happen.
The foods we eat provide us with a range of nutrients: vitamins, minerals, water, fat, carbohydrates, fibre, and protein. These nutrients are put to different uses — as building materials to construct the tissues and organs from which our bodies are made; as the components of the molecular machinery that keeps our cells running as they should. All of these uses are unified by a common theme: a requirement for energy to make them happen.
Name the 7 nutrients that humans need
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There are seven different nutrients:
- carbohydrates
- proteins
- fats
- minerals
- vitamins
- fibre
- water
Identify examples of each type of food
Test foods for starch, proteins and fats
All living things contain organic macromolecules: Lipids, proteins, carbohydrates and nucleic acids. Characteristic for these organic molecules is that they are made up of only a small number of elements: carbon, hydrogen, oxygen, and to smaller amounts nitrogen, phosphorus and sulfur. They are called "macromolecules" because they are very large, containing long chains of carbon and hydrogen atoms and often consists of repeating smaller molecules bonded together in a repeating pattern (polymers).
Macromolecule building block
protein amino acids
carbohydrates monosaccharides
lipids glycerol + fatty acids
nucleic acids nucleotides
Science labs can test for different food groups using specialized tests
Here are some common assays and the chemicals that are used to test them:
Starch- Lugol's iodine
Protein- Biuret Reagent
Polysaccharides (fats)- Sudan III stain
Glucose- Benedict's Solution
Macromolecule building block
protein amino acids
carbohydrates monosaccharides
lipids glycerol + fatty acids
nucleic acids nucleotides
Science labs can test for different food groups using specialized tests
Here are some common assays and the chemicals that are used to test them:
Starch- Lugol's iodine
Protein- Biuret Reagent
Polysaccharides (fats)- Sudan III stain
Glucose- Benedict's Solution
Give an example of a food or drink that is a good source of that nutrient
Despite what you see in some diet books and TV programs, healthy eating can be really straightforward. A diet based on starchy foods such as potatoes, bread, rice and pasta; with plenty of fruit and vegetables; some protein-rich foods such as meat, fish and lentils; some milk and dairy foods; and not too much fat, salt or sugar, will give you all the nutrients you need.
When it comes to a healthy diet, balance is the key to getting it right. This means eating a wide variety of foods in the right proportions, and consuming the right amount of food and drink to achieve and maintain a healthy body weight.
When it comes to a healthy diet, balance is the key to getting it right. This means eating a wide variety of foods in the right proportions, and consuming the right amount of food and drink to achieve and maintain a healthy body weight.
- Fruit and vegetables are a vital source of vitamins and minerals. It's advised that we eat at least five portions of a variety of fruit and vegetables each day.
- Starchy foods should make up around one third of everything we eat. This means we should base our meals on these foods. Potatoes are an excellent choice and a great source of fibre. Leave the skins on where possible to keep in more of the fibre and vitamins.
- Meat, fish, eggs and beans: all good sources of protein. These foods are all good sources of protein, which is essential for the body to grow and repair itself. They are also good sources of a range of vitamins and minerals, including iron, zinc and B vitamins. It is also one of the main sources of vitamin B12. Try to eat lean cuts of meat and skinless poultry whenever possible to cut down on fat.
- Milk and dairy foods such as cheese and yoghurt are good sources of protein. They also contain calcium, which helps keep your bones healthy. To enjoy the health benefits of dairy without eating too much fat, use semi-skimmed, 1% fat or skimmed milk, as well as lower-fat hard cheeses or cottage cheese, and lower-fat yoghurt.
- Fats and sugar are both sources of energy for the body, but when we eat too much of them we consume more energy than we burn, and this can mean that we put on weight. This can lead to obesity, which increases our risk of type 2 diabetes, certain cancers, heart disease and stroke.
Analyse information to make decisions about healthy lifestyles
image fromwww.kidneyfund.org
Just because a food is high in vitamins doesn't mean it's healthy overall. Sure, it's great that your favorite cereal gives you a shot of vitamins and minerals. But what if it's also loaded with sugar?
Eating healthy means choosing lots of different types of food throughout the day to get all the nutrients you need, such as vitamins, minerals, carbohydrates, fiber, and — yes — even fat.
So how do you figure all this out? Thank goodness for food labels! Labels give you information that can help you decide what to choose as part of an overall healthy eating plan. For example, it may be OK to eat a sugary cereal if you make up for it by not eating much sugary stuff for the rest of the day. Checking the labels on foods can alert you when a food is high in something like sugar so you can be prepared to make tradeoffs.
Eating healthy means choosing lots of different types of food throughout the day to get all the nutrients you need, such as vitamins, minerals, carbohydrates, fiber, and — yes — even fat.
So how do you figure all this out? Thank goodness for food labels! Labels give you information that can help you decide what to choose as part of an overall healthy eating plan. For example, it may be OK to eat a sugary cereal if you make up for it by not eating much sugary stuff for the rest of the day. Checking the labels on foods can alert you when a food is high in something like sugar so you can be prepared to make tradeoffs.
Explain the importance of a balance diet
Your food choices each day affect your health — how you feel today, tomorrow, and in the future. Good nutrition is an important part of leading a healthy lifestyle. Combined with physical activity, your diet can help you to reach and maintain a healthy weight, reduce your risk of chronic diseases (like heart disease and cancer), and promote your overall health.
MAINTAINING A BALANCED DIET BY HEALTHY EATING CAN:
MAINTAINING A BALANCED DIET BY HEALTHY EATING CAN:
- Give you vitality and energy for life
- Help you stay at a weight that's right for you
- Boost your immune system
- Improve sports performance
- Delay the effects of aging
- Keep you active and fit into old age
- Help beat tiredness and fatigue
- Protect teeth and keep gums healthy
- Enhance your ability to concentrate and possible alter mood
- Help prevent serious illnesses like heart disease, certain cancers, mature-age onset diabetes, and gallbladder disease
image from www.bestwaytoloseweight4u.com
Explain how too little or too much of a nutrient can cause diseases
Nutritional imbalance can be caused by an inability of the body to absorb certain nutrients or result from a poor diet. Depending on the nutrients in short or excess supply, imbalances create unpleasant side effects and conditions that could lead to serious disease.
- When you are overeating, you chronically take in more food energy, or calories, than you need, leading to weight gain, overweight and obesity. Overeating puts you at risk for heart disease, cancer, diabetes and complications related to overweight and obesity, according to the World Health Organization. Your body needs the right amount of energy to function properly, so overeating is likely to leave you feeling tired and irritable, too.
- When a person is not getting enough food or not getting the right sort of food, malnutrition is just around the corner. Even if people get enough to eat, they will become malnourished if the food they eat does not provide the proper amounts of micronutrients - vitamins and minerals - to meet daily nutritional requirements.
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image from visual.ly
Evaluate the danger of eating salt
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Salt is an essential part of our health. Adults need less than 1 gram per day and children need en less. On an average we are eating approximately 8.1 g of salt per day, far more than the recommended maximum of 6 g per day, putting us at risk of all of the health problems.
Too much salt increases our blood pressure. Raised blood pressure (hypertension) is the major factor which causes strokes, heart failure and heart attacks, the leading causes of death and disability throughout the world. There is also increasing evidence of a link between high salt intake and stomach cancer, osteoporosis, obesity, kidney stones, kidney disease and vascular dementia and water retention.
Too much salt increases our blood pressure. Raised blood pressure (hypertension) is the major factor which causes strokes, heart failure and heart attacks, the leading causes of death and disability throughout the world. There is also increasing evidence of a link between high salt intake and stomach cancer, osteoporosis, obesity, kidney stones, kidney disease and vascular dementia and water retention.
Recall the parts of the digestive system and their function
Your digestive system is uniquely constructed to perform its specialized function of turning food into the energy you need to function and packaging the residue for waste disposal.
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Explain enzymes and their function
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Enzymes are important in digestion. Digestion is the breakdown of large molecules, carbohydrates, proteins and fats, into smaller, soluble molecules that can be absorbed into the blood.
Enzymes are considered to be catalyse for different digestion reactions. Catalysits help speed up the reaction of breaking down the foods.
Enzymes are considered to be catalyse for different digestion reactions. Catalysits help speed up the reaction of breaking down the foods.
- Amylase catalyses the breakdown of starch into sugars in the mouth and small intestine
- Proteases catalyse the breakdown of proteins into amino acids in the stomach and small intestine
- Lipases catalyse the breakdown of fats and oils into fatty acids and glycerol in the small intestine
Describe what happens as food passes through the digestive system
Explain what is meant by digestion, egestion and ingestion
- Digestion: process in which large insoluble molecules of food are broken down into smaller ones.
- Absorption: the process by which soluble molecules produced by digestion are taken from the gut (occurs mostly in the small intestine.) The soluble products of digestion are then transported to the various tissues by the circulatory system.
- Assimilation: the cells of the tissues absorb the molecules for use.
- Egestion: removal of waste- undigested- products as faeces.
- Excretion: removal of waste products that have been in the body.
Key Terms
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scientific method
variables control variable independent variable bolus chyme bile enzymes diabetes anorexia salivary gland |
dependent variable
hypothesis carbohydrates proteins lipids intestine stomach villi bolemia gullet |
vitamins
minerals fibre nutrition malnutrition gullet faeces liver pancreas kwashorkor |
constipation supplements
fatty acid glucose amino acid respiration joules calories insulin saliva |
deficiency disease
balanced diet digestion peristalsis ingestion egestion excretion oesophagus obese appendix |
Classroom Material:
Nutrition
Food Group Fill In the Blank worksheet
Food Diet Diary
Vitamins and Minerals Reading exercise
Food Label Facts information sheet
Testing For Foods practical
NASA Food Pyramid
"Is My Diet OK"
Nutrition Webquest
Food advertisements vs. cigarette advertisements The tricks fast food companies use to lure you in from news.com.au, Jun 2014
Ban TV Junk Food - BBC News
Food and Activity worksheet
Energy Requirement worksheet..
How Is Fitter worksheet
Digestive System
Digestive System Parts worksheet
Digestive System Webquest
Journey Through the Digestive System
Enzyme worksheet.
Nutrition
Food Group Fill In the Blank worksheet
Food Diet Diary
Vitamins and Minerals Reading exercise
Food Label Facts information sheet
Testing For Foods practical
NASA Food Pyramid
"Is My Diet OK"
Nutrition Webquest
Food advertisements vs. cigarette advertisements The tricks fast food companies use to lure you in from news.com.au, Jun 2014
Ban TV Junk Food - BBC News
Food and Activity worksheet
Energy Requirement worksheet..
How Is Fitter worksheet
Digestive System
Digestive System Parts worksheet
Digestive System Webquest
Journey Through the Digestive System
Enzyme worksheet.
Useful Links:
Click here for a fun interactive game on Nutrition
Click here for additional information on the classification of foods
Click here for a fun interactive game on Nutrition
Figuring out Food Labels - Kids Health
Click here for some additional information on enzymes
Look at the bitesize activity but focus only on the food part (it is also about drugs which is Year 9)
Look at the bitesize pages for nutrients, diet, the digestive system and enzymes.
Try Doc Brown´s quiz.
Label the digestive system on the CGP books website.
Learn about enzymes on skoool.co.uk (a bit harder than Year 8 level)
Videos Clips:
Click here for a fun interactive game on Nutrition
Click here for additional information on the classification of foods
Click here for a fun interactive game on Nutrition
Figuring out Food Labels - Kids Health
Click here for some additional information on enzymes
Look at the bitesize activity but focus only on the food part (it is also about drugs which is Year 9)
Look at the bitesize pages for nutrients, diet, the digestive system and enzymes.
Try Doc Brown´s quiz.
Label the digestive system on the CGP books website.
Learn about enzymes on skoool.co.uk (a bit harder than Year 8 level)
Videos Clips:
Companies spend billions of dollars promoting sweet cereals, soda, and fast food to the most impressionable viewers. Help steer your kids away from all the unhealthy marketing.
Bill Nye looks at Nutrition
Two great video clips on the importance of a healthy diet
Three video clips on eating disorders
Several legal suits have been brought against McDonald's Restaurants that they are knowingly selling food that is unhealthy. Some of the court decisions have stated that the plaintiffs would have a claim if they could prove that eating the food every day for every meal is dangerous. As such, documentarian conducts an unscientific experiment using himself as the guinea pig: eat only McDonald's for thirty days, three meals a day.
Join Jamie Oliver in curing the obesity epidemic. We join hands with him. Obesity is the biggest killer today....and it is preventable. How to cure obesity. Teach kids how to cook. Teach kids about food. Nutrition should be taught in schools. Teach kids by showing them what is in food. Kids must learn what vegetables look like in its natural state. Living healthy is easy.
Animation showing the enzymatic process
Bill Nye talks about Digestion
