Why do we need food?

Food Type Use Carbohydrate Fat Protein Long term energy Fast energy Protecting organs and long term energy store Making muscle, enzymes, skin, hair Brainstorm 4 main food types and where they come from Fat and protein meat, fish Sugars fruit, sweet things Crbs from pasta, potatoes etc

Food tests Food type Test Protein Sugar Fat Carbohydrate Biuret turns purple if protein is present Benedicts turns from blue to red/brown if sugar is present Greaseproof paper gets an oily residue Iodine turns blue/black if starch is present KOH and CuSO4 Biuret Expt H/O whats in our foodtest a variety of foods

The Digestive System Buccal cavity Oesophagus Stomach Small Intestine (Breaking food down into smaller pieces) Buccal cavity Oesophagus Stomach Small Intestine Liver Large Intestine Gall Bladder Pancreas Rectum Anus H/O anticipation guide digestion and absorption H/O vocab square digestion H/O game structure of digestive system Stretch out person until intestine is straight they are 8m long, HORSE 30M! shine torch Ingestion Digestion Absorbtion Egestion

Mouth (mechanical breakdown) Teeth Incisors used for cutting Tongue Canines used for stabbing and holding Molars large surface area used for grinding Tongue used for muscular activities and sensing the taste of food Masseter muscle zygomatic arch, cranial ridge = carnivore Herbivore – diastema plate for incisors to press against Epiglotis prevents food going down the wrong way

Salivary Glands Produce saliva Three pairs Prevents bacterial infection Lubrication Contains salivary amylase Breaks down starch Three pairs Parotid: Largest Submandibular Sublingual: Smallest

Oesophagus Approximately 25cm long Moves food from the throat to the stomach Muscle movement called peristalsis If acid from the stomach gets in here that’s heartburn. A good way to describe peristalsis is an ocean wave moving through the muscle. These diagrams don’t separate the esophagus from the mouth functions, you might want to talk about what happens in the mouth too.

Stomach Stores the food you eat Chemically breaks it down into tiny pieces Mixes food with digestive juices Acid in the stomach kills bacteria The stomach takes around 4 hours to do it’s job on the food, depending on what kinds of food are digested. Digestive juices HCL and pepsin (protein breakdown)

Small Intestine Small intestines are roughly 6 metres long. Enzymes and bile are added. Villi increase the surface area to help absorbtion. Nutrients from the food pass into the bloodstream through the small intestine walls. Enzymes breakdown large molecules. Villi look like little fingers Blood system is in close proximity to carry nutrients away around the rest of the body

Liver Directly affects digestion by producing bile Bile is an enzyme that helps dissolve fat Processes nutrients in the blood, filters out toxins and waste. Is often called the body’s energy factory Livers can regenerate missing pieces if necessary. Is one of the largest organs in the body.

Gall Bladder Stores bile from the liver Delivers bile when food is digested Fatty diets can cause gallstones Explain to students that removing the stones typically means removing the gallbladder, but that the body eventually adjusts to not having the bile stored.

Pancreas Produces compounds to digest fats and proteins Neutralizes acids that enter small intestine Regulates blood sugar by producing insulin Explain the difference between the two types of diabetes. In type 1, the pancreas fails to produce enough insulin. In type 2, the body stops responding properly to the insulin it creates. Enzymes for breakdown of protein, cbh, sugar

Large Intestine About 1.5 metres long Accepts what small intestines don’t absorb. Absorbs water and minerals from the waste matter. Absorption means taking into the body via the blood stream. Depending on the maturity of the group, you can talk about the feces leaving via the anus. Mention the appendix at the bottom of the ascending colon and that it might have been used long ago but is not today Mention the portions of the large intestine, ascending, transverse, descending, sigmoid, and rectum (last one if the audience is mature enough)

Rectum and Anus Rectum Anus About 15cm long Stores waste before egestion. Anus Muscular ring that controls egestion. H/O game word play