Digestion

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

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

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

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

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

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

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

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

Inside A Molar

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

Peristalsis http://www.pennhealth.com/health_info/animationplayer/peristalsis.html 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

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 http://www.ahealthyme.com/Imagebank/digestive.swf

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

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

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

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

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

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

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

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