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FOOD
Food is any substance absorbed into the body that supplies nutrients to the body cells for energy, growth and repair of tissues, regulation of life processes and staying healthy.
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The IMPORTANCE of FOOD
Food serves as a fuel, giving energy and heat to the body cells.
Food supplies the building material for growth and repair and replacement of damaged tissues
Food supplies important regulating substances that are essential for the correct functioning of cells and metabolic processes
Food is used by the body to stay healthy and protect it from diseases
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DIET
Diet refers to the daily food we eat and liquids we drink
A balanced diet contains all the nutrients in sufficient quantities and correct proportions needed for normal growth and good health
Malnutrition refers to the harmful effects on the body of eating to little or eating to much of the wrong kinds of food.
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Water in your dietWater is important in a healthy diet because:
Most of your body consists of water
All the chemical reactions in your body take place in water.
Water serves as a solvent for nutrients, wastes and gases
Water transports nutrients and waste products in the body
Water plays a role in digestion
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DEFICIENCY DISEASESResulting from not eating enough proteins or vitamins or minerals
Disease Cause Result
Beriberi Lack of vitamin B Nervous system affected
Scurvy Lack of vitamin C Gums bleed and teeth loosen
Pellagra Lack of nicotinic acid (part of vitamin B)
Dermatitis, dementia, diarrhoea
Rickets Lack of vitamin D Bones weaken and are malformed
Kwashiorkor Lack of protein, to much carbohydrates
Swollen stomach, skin appears red, hair loses colour and organs waste away
Marasmus General lack of food Thin, weak and stunted growth
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EATING DISORDERS
This occurs when you have access to a healthy balanced diet and choose not to eat, or to eat too much
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Disorder Cause Result
Anorexia nervosa
Psychological illness that makes a person have an intense fear of gaining weight
Fatigue, muscle weakness, yellowish skin, brittle hair, osteoporosis and amenorrhea
Anorexia bulimia
Psychological illness that makes a person overeat and then cause themselves to vomit (Binge and Purge)
Fatigue, muscle weakness and rotting teeth
Obesity Overeating and lack of exercise
Cholesterol, high blood pressure and heart failure
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You are a tube inside a tube…
The tube starts
here:
And although
there are a few
twists and turns
along the way…
It comes out here:
Anything that goes
in the top hole
(mouth) does not
become part of the
body until it is
absorbed (taken in)
in a part called the
small intestine.
This tube is
called the
ALIMENTRY
CANAL or GUT.
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Peristalsis
The contraction and relaxation of the muscles in the oesophagus to pass the food along
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The Mouth
Food is crushed and ground up by teeth
The salivary glands make saliva which makes the food moist and easy for swallowing
Amylase enzyme (in saliva) breaks the carbohydrate starch down into glucose.
Tongue keeps food between teeth when chewing, mixes food with saliva, moulds food into a bolus, assists with swallowing process
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Stomach
Stomach muscles contract and relax to mechanically break down the food
They also mix the food up with gastric juice and hydrochloric acid The acid kills germs in the food
Food spends about 3-4 hours in here.
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PANCREAS
Secretes enzymes which digest food
Also secretes hormones: Insulin and glucagon which control the blood sugar levels
If your insulin doesn’t work porperly you develop Diabetes
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The Duodenum (first section of small intestine – just out of the
stomach) The first part of the small intestine is
called the duodenum.
Food, still mixed with gastric juice is squirted into it from the stomach.
The food is now a semi liquid, highly acidic mush.
It needs to be neutralised and digestion needs to be continued…
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Absorption
The food is then ABSORBED through the wall of the small intestine into the blood stream.
To do this effectively, the small intestine needs to have a large surface area.
This is achieved in the following ways:
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Absorption The tube is over 6 meters long
The inner wall of the tube has bends in it
The wall is covered in villi (small finger-like structures)
Outer wall
Inner wall
Pathway
for Food
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After absorption: The Liver
The liver produces bile which digests fatty foods
The gall bladder temporarily stores bile
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Egestion
Any indigestible food (e.g. fibre) passes into the large intestine (colon).
Water is absorbed back into the body.
The food becomes a solid waste called faeces.
Faeces are stored in the rectum and removed through the anus. This removal is called EGESTION.
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Ingestion• Intake of food
Digestion• Covert food into soluble nutrients
Absorption
• Soluble nutrients taken up by the blood stream
Egestion• Undigested food passes out of the body