1. Digestion

2. Food Groups There are 3 big food groups: Fats Proteins Carbohydrates
We also need Vitamins and Minerals to stay healthy

3. Proteins These are needed for growth and repair
This is especially important for children and bodybuilders
Foods rich in proteins include dairy products e.g. milk, cheese, yoghurts etc.
These are also high in fat
Meats are high in protein and white meat does not contain much fat

4. Carbohydrates This should make up the majority of your diet
Carbohydrates include sugars and complex types
Sugars give you instant energy e.g. sweets, Pepsi, chocolate
Complex carbohydrates release energy slowly e.g. pasta, rice, potatoes

5. Fats These contain lots of energy They are essential to the body
We need a certain amount of body fat to be healthy
We also need cholesterol in our cell membranes

6. Vitamins We need these in small amounts
Vitamin C is needed to keep us healthy we find it in citrus fruits and apples (deficiency causes scurvy)
Vitamin D is made by sunlight, as well as milk etc. (a lack of Vitamin D causes Rickets)
Vitamin A is needed for good night vision. It is found in carrots

7. Minerals
Iron is needed to make haemoglobin in red blood cells. It is found in red meat
Deficiency causes anaemia
Calcium is needed to make strong bones and teeth. It is found in milk and dairy products
Iodine is needed to produce growth hormone and keep up the metabolic rate. It is found in sea food

8. The Teeth
We get two sets of teeth during our lifetime, this is because your jaw grows until you are an adult
Milk teeth- there are 20
Permanent teeth start appearing after 6 years of age
There are 28 at first, with 4 wisdom teeth making this up to 32

9. Types Of Teeth Incisors- cut and slice food
Canines- are sharp to pierce and rip meat
Pre-molars- chew soft food (young children do not have molars)
Molars- chew hard food

10. Inside A Molar

11. Enzymes Amylase breaks starch into maltose in the mouth
Proteases are found in the stomach
They break down proteins
Fats and maltose are broken down in the small intestine
Fats are broken down by lipase

12. Peristalsis
This is the pushing action of food through the digestive system
The digestive system is about 9 m (30 feet) long
This is 5 times your height
A cow has 3 stomachs allowing it to regurgitate your food

13. The Oesophagus
Food is broken down and liquid is added to it in the mouth
This is packed into a bolus
The bolus is pushed down the food pipe by peristalsis
The muscles behind the bolus contract and the ones ahead of it relax

14. The Stomach
The Stomach contains Hydrochloric acid to kill bacteria and fungi
It is muscular and squeezes food

15. Small Intestine
This is the most important organ, it is responsible for absorption
Broken down food has to be absorbed into the blood, then it is sent to the muscles and brain
The small intestine has a large surface area to absorb lots of these food molecules

16. The Villi The small intestine is covered in villi
These add to the surface area
They absorb more food into the blood
Each villus had a blood capillary to give food to

17. How long does it take to digest food?
Oranges, grapefruit, grapes - 30 min. Apples, pears, peaches, cherries etc. - digest in 40 min.
Chicken – 1 ½ to 2 hours digestion time (without skin) Turkey - 2 to 2 ¼ hours digestion time (without skin) Beef, lamb - 3 to 4 hours digestion time

18. The Large Intestine
Waste food is passed from the small intestine into the large intestine
Water is reabsorbed from waste food
Waste is stored in the rectum
This is the end of the large intestine
Defecation is when food passes out of the anus

19. Rectum and Anus The rectum is the last 12 cm of the large intestine
It stores faeces
Sphincter muscles control the movement of these faeces
The anus is the hole which faeces are egested from the body

20. Liver The liver detoxifies the blood, breaking down alcohol and drugs
It stores food (Glycogen)
It produces bile (which helps break down fats)
It breaks down old red blood cells
It can heal itself given enough time

21. Pancreas The pancreas produces Insulin
This regulates the amount of glucose in the blood
If the gets too high or too low it can damage the body and the diabetic can go into a coma