THE HUMAN DIGESTIVE SYSTEM The journey of food

THE HUMAN DIGESTIVE SYSTEM The journey of food or chew it and poo it!

The Mouth. n n Teeth break down food into small pieces. Salivary glands make saliva. Chewed food gets mixed with saliva. Saliva contains enzymes, which start to digest starch to sugar.

Teeth. n n Four Types Incisors - Cutting Canine – Grip and tearing Molars and Pre. Molars for grinding Notes on next page

There are four types of teeth Incisors cut and slice through food Canines grip and tear food Premolars chew and crush food Molars chew and crush food

Teeth. n n n Enamel- Hard outer layer Dentine – Softer interior Plaque - Bacteria that attack the teeth

Digestion -Breaking food down into smaller pieces Food Teeth begin process of breaking down food Saliva contains an ENZYME (Amylase) Long chains of sugar called Starch Shorter sugars that start to be digested

Digestive Enzyme n n Enzymes are biological catalysts A digestive enzyme is a protein that acts as a catalyst in breaking down food Starch Amylase (saliva) Sugar

Digestion Saliva contains an ENZYME called Amylase- (speeds up the reaction) Amylase Long chains of sugar called Starch Maltase Maltose Glucose Shorter sugars that start to be digested

Digestion –This also works with other groups for example proteins ENZYME Eggs Teeth begin process of breaking down food Complicated Protein Amino Acids etc Used for growth and repair

To investigate the action of the digestive enzyme (amylase) on starch n Add starch and saliva to two test tubes raise temperature to 37 degrees in a water bath Test one for starch (iodine) ¨ Test the other for glucose (Benedict’s solution and heat) ¨

To investigate the action of the digestive enzyme (amylase) on starch Add Iodine solution Starch+Saliva Solution Benedict’s solution Heat it up Starch Solution only Proves starch has turned to sugar

Substrate The substrate is the substance that an enzyme acts on. Starch is the substrate for the enzyme amylase. Notes on next page

Summary Substrate Enzyme Product Starch Amylase Maltose

5 Stages of Nutrition Ingestion-Eating n Digestion-Breaking up n Absorption-Into body at small intestine n Assimilation-Used by the cells n Egestion-Pushed out n

The Oesophagus – Food Pipe. n n n Passes food down to your stomach. The oesophagus has circular muscles in its wall. These muscles contract and squeeze in behind the food to push it along.

The Stomach n n n Muscular bag that holds 2 litres of food. Secretes Hydrochloric Acid. Makes digestive juices. Muscular walls churn the food making sure it’s all mixed. After 2 -3 hours churning it’s a runny liquid. -CHIME

The Small Intestine n n Actually 6 m long! Plays important roles in digestion and absorption n Two important liquids are added here: Pancreatic juices Bile

Absorption n Digested food has to pass into the blood through the gut wall. Well designed – thin lining, good blood supply and a VERY LARGE surface area. It has a folded inner lining, millions of tiny VILLI

Pancreas n n n Produces digestive enzymes E. g. amylase Also makes INSULIN to control sugar in body

Liver n n n After food has been absorbed into the blood, the food is taken to the liver. It removes toxins The food dissolved in plasma is then taken to other parts of the body.

The Large Intestine. n n Mainly fibre, dead cell, bacteria and water reach here! As it moves along here most of the water is absorbed into the blood. Faeces are stored in the rectum. Eventually egested out of the anus, roughly 24 – 48 hours after eating.

1 Mouth/ Teeth 2 Liver 3 Large Intestine 4 xxxxxxx 5 Appendix 6 Rectum 7 Food Pipe 8 Stomach 9 Gall Bladder 10 Colon 11 Small Intestine

Experiment To investigate the action of amylase on starch

Aim n To see if we mix saliva and starch if the starch will turn into sugar

Method To investigate the action of amylase on starch 1. 2. 3. Set up the apparatus as shown in the diagram. Leave the apparatus for 10 minutes (to allow the amylase to act on the starch). Remove a few drops of each solution and mix with a few drops of iodine solution (to test for starch). TUBE A TUBE B Starch solution + Amylase Starch solution Water bath at 37°C

Results To investigate the action of amylase on starch Final colour Tube Contents Tube A Starch and amylase Red / yellow Tube B Starch Blue / black Conclusion No starch present Starch present

Conclusion To investigate the action of amylase on starch n n In tube A the starch was broken down by the action of the enzyme amylase. In tube B starch was not broken down as there was no enzyme. This shows that amylase breaks down starch.

5 Stages Nutrition Teeth Liver Digestive system Small Intestine Amylase Digestion Breaking up

H/W P 36 n Q 4. 1 , 4. 2 and 4. 3 n