Food

Type

• Carbohydrate

• Fat

• Protein

Use

• Long term energy• Fast energy• Protecting organs and

long term energy store• Making muscle, enzymes,

skin, hair

Food tests

Food type

• Protein

• Sugar

• Fat

• Carbohydrate

Test

• 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

The Digestive System

• Buccal cavity• Oesophagus• Stomach• Small Intestine• Liver• Large Intestine• Gall Bladder• Pancreas• Rectum• Anus

(Breaking food down into smaller pieces)

Mouth(mechanical breakdown)• Teeth

Incisors used for cutting

Canines used for stabbing and holding

Molars large surface area used for grinding

• Tongue

used for muscular activities

and sensing the taste of food

Salivary Glands

• Produce saliva1. Prevents bacterial infection2. Lubrication3. Contains salivary amylase

• Breaks down starch

• Three pairs1. Parotid: Largest2. Submandibular3. 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.

Stomach

• Stores the food you eat

• Chemically breaks it down into tiny pieces

• Mixes food with digestive juices

• Acid in the stomach kills bacteria

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.

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

Gall Bladder

• Stores bile from the liver

• Delivers bile when food is digested

• Fatty diets can cause gallstones

Pancreas

• Produces compounds to digest fats and proteins

• Neutralizes acids that enter small intestine

• Regulates blood sugar by producing insulin

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.

Rectum and Anus

• Rectum– About 15cm long

– Stores waste before egestion.

• Anus– Muscular ring that controls egestion.