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Humans

. 2.23 understand that a balanced diet should include
appropriate proportions of carbohydrate, protein,
lipid, vitamins, minerals, water and dietary fibre

. 2.24 identify sources and describe functions of
carbohydrate, protein, lipid (fats and oils), vitamins A, C
and D, and the mineral ions calcium and iron, water and…

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Nutrition
Human
A balanced diet should include:

Carbohydrates
Contain the elements carbon, hydrogen and oxygen
Starch, glycogen are complex long chained carbohydrates made
up of smaller units (glucose/maltose)
Provide energy for respiration
Found in pasta, rice, sugar
Proteins
Long chains of amino acids
Contain carbon, hydrogen, oxygen and nitrogen atoms…

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Aids the movement of food through the gut
Found in whole meal bread
Energy requirements

Activity level
Active people (physical jobs: builders) need more energy
than non-active people (office jobs)
Age
Children and teenager need more energy for growth
Pregnancy
Pregnant women need more energy to provide the energy
for…

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Structure of the human alimentary canal (gut)




Mouth
Salivary glands in the mouth produce amylase in the saliva
Food is broken into smaller pieces by the teeth (mechanical digestion)
The tongue molds the small food pieces into a bolus (easy to swallow)
Oesophagus
A muscular tube that connects the mouth…

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Excess water is absorbed into the blood by osmosis

Peristalsis

Food moves along the gut by contracting and relaxing the muscles in the gut
wall
The circular muscles contract and the longitudinal muscles relax
(narrow)

The circular muscles relax and the longitudinal muscles contract (wide)


The structure of a small…

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Villi are one cell thick- diffusion is quick



Five main stages of Digestion

Ingestion
Taking food into the body (mouth)

Digestion
The breakdown of large insoluble food molecules into small soluble food
molecules

Absorption
Digested molecules enter the blood stream via diffusion through the
walls of the intestines
Food molecules-…

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